Samacheer Kalvi 11th Bio Zoology Guide Chapter 10 Neural Control and Coordination

Tamilnadu State Board New Syllabus Samacheer Kalvi 11th Bio Zoology Guide Pdf Chapter 10 Neural Control and Coordination Text Book Back Questions and Answers, Notes.

Tamilnadu Samacheer Kalvi 11th Bio Zoology Guide Chapter 10 Neural Control and Coordination

11th Bio Zoology Guide Neural Control and Coordination Text Book Back Questions and Answers

Part – I

I. Choose The Best Options

Question 1.
Which structure in the ear converts pressure waves to action potentials?
a) Tympanic membrane
b) Organ of Corti
c) Oval window
d) Semicircular canal
Answer:
b) Organ of Corti

Question 2.
Which of the following pairings is correct
a) Sensory nerve – afferent
b) Motor nerve – afferent
c) Sensory nerve – ventral
d) Motor nerve – dorsal
Answer:
a) Sensory nerve – afferent

Question 3.
During synaptic transmission of nerve impulse, a neurotransmitter (P) is released from synaptic vesicles by the action of ions
(Q). Choose the correct P and Q.
a) P = Acetylcholine, Q = Ca⁺⁺
b) P = Acetylcholine, Q = Na⁺
c) P = GABA, Q = Na⁺
d) P = Cholinesterase, Q = Ca⁺⁺
Answer:
a) P = Acetylcholine, Q = Ca⁺⁺

Question 4.
Examine the diagram of the two cell types A and B given below and select the correct option.
a) Cell – A is the rod cell found evenly all over the retina
b) Cell – A is the cone cell more concentrated in the fovea centralis
c) Cell – B is concerned with colour vision in bright light
d) Cell – A is sensitive to bright light intensities

Answer:
c) Cell – B is concerned with colour vision in bright light

Question 5.
Assertion- The imbalance in the concentration of Na⁺, K^+, and proteins generates an action potential.
Reason: To maintain the unequal distribution of Na⁺ and K⁺, the neurons use electrical energy.
a) Both Assertion and Reason are true and Reason is the correct explanation of the Assertion.
b) Both Assertion and Reason are true but the Reason is not the correct explanation of Assertion.
c) Assertion is true, but Reason is false.
d) Both Assertion and Reason are false.
Answer:
a) Both Assertion and Reason are true and Reason is the correct explanation of the Assertion.

Question 6.
Which part of the human brain is concerned with the regulation of body temperature?
a) Cerebellum
b) Cerebrum
c) Medulla oblongata
d) Hypothalamus
Answer:
d) Hypothalamus

Question 7.
The respiratory centre is present in the
a) Medulla oblongata
b) Hypothalamus
c) Cerebellum
d) Thalamus
Answer:
a) Medulla oblongata

Question 8.
Match the following human spinal nerves in column I with their respective number in column II and choose the correct option
Column I Column 11
(P) Cervical nerves
(Q) Thoracic nerve
(R) Lumbar nerve
(S) Coccygeal nerve
(i) 5 pairs
(ii) 1 pair
(iii) 12 pairs
(iv) 8 pairs
a) (P-iv), (Q-iii), (R-i), (S-ii)
b) (P-iii), (Q-i), (R-ii), (S-iv)
c) (P-iv), (Q-i), (R-ii), (S-iii)
d) (P-ii), (Q-iv), (R-i), (S-iii)
Answer:
a) (P-iv), (Q-iii), (R-i), (S-ii)

Question 9.
Which of the following cranial nerve controls the movement of eye ball?
a) Trochlear nerve
b) Optic nerve
c) Olfactory nerve
d) Vagus nerve
Answer:
a) Trochlear nerve

Question 10.
The abundant intracellular cation is
a) H⁺
b) K⁺
c) Na⁺
d) Ca⁺⁺
Answer:
b) K⁺

Question 11.
Which of the following statements is wrong regarding the conduction of nerve impulse.
a) In a resting neuron, the axonal membrane is more permeable to K⁺ ions and nearly impermeable to Na⁺ ions.
b) Fluid outside the axon has a high concentration of Na⁺ ions and a low concentration of K⁺, in a resting neuron.
c) Ionic gradient s are maintained by Na⁺ K⁺ pumps across the resting membrane, which transport 3 Na ions outwards for 2K⁺ into the cell.
d) A neuron is polarized only when the outer surface of the axonal membrane possess a negative charge and its inner surface is positively charged.
Answer:
b) Fluid outside the axon has a high concentration of Na⁺ ions and a low concentration of K⁺, in a resting neuron.

Question 12.
All of the following are associated with the myeline sheath except
a) Faster conduction of nerve impulses
b) Nodes of Ranvier forming gaps along the axon
c) Increased energy output for nerve impulse conduction
d) Saltatory conduction of action potential
Answer:
c) Increased energy output for nerve impulse conduction

Question 13.
Several statements are given here in reference to cone cells which of the following option indicates all correct statements for cone cells? Statements
(i) Cone cells are less sensitive in bright light than Rod cells
(ii) They are responsible for colour vision
(iii) Erythropsin is a photo pigment which is sensitive to red colour light
(iv) They are present in fovea of retina
a) (iii), (ii) and (i)
b) (ii), (iii) and (iv)
c) (i), (iii) and (iv)
d) (i), (ii) and (iv)
Answer:
c) (i), (iii) and (iv)

Question 14.
Which of the following statement concerning the somatic division of the peripheral neural system is incorrect?
a) Its pathways innervate skeletal muscles
b) Its pathways are usually voluntary
c) Some of its pathways are referred to as reflex arcs
d) Its pathways always involve four neurons
Answer:
d) Its pathways always involve four neurons

Question 15.
When the potential across the axon membrane is more negative than the normal resting potential, the neuron is said to be in a state of
a) Depolarization
b)FIyperpo1ariation
c) Repolarization
d) Hypopolaiization
Answer:
c) Repolarization

Question 16.
Why is the blind spot called so?
Answer:
Slightly below the posterior pole of the eye, the optic nerve and the retinal blood vessels enter the eye. This region is devoid of rods and cones. Hence, this region is called a blind spot.

Question 17.
Sam’s optometrist tells him that his intraocular pressure is high. What is this condition called and which fluid does it involve?
Answer:

• The increase in intraocular pressure leads to the disease called Glaucoma.
• Any block in the canal of Schlemm increases the intraocular pressure of aqueous humor and leads to ‘Glaucoma’ where the optic nerve and the retina are compressed due to pressure.

Question 18.
The action potential occurs in response to a threshold stimulus: but not at sub-threshold stimuli. what is the name of the principle involved?
Answer:
The olfactory nerve carries the sense of smell to the sensory strip present in the cerebrum. The sensory areas are present in the parietal lobe of the cerebrum. The stimuli of smell reaches the mammillary bodies present in the hypothalamus. This produces olfactory reflexes and emotional responses to odour.

Question 19.
Pleasant smell of food urged Ravi to rush into the Kitchen. Name the parts of the brain involved in the identification of food and emotional responses to odour
Answer:
The hypothalamus contains a pair of small rounded body called mamillary bodies that are involved in olfactory reflexes and emotional responses to odour
This is also act as centre for appetite thirst and heat regulation.

Question 20.
Cornea transplant in humans is almost never rejected State the reason.
Answer:
Cornea does not have blood vessels. Hence there is no possibility of rejection when the cornea is transplanted from one person to another person.

Question 21.
At the end of repolarisation, the nerve membrane gets hyperpolarized Why?
Answer:
If repolarization becomes more negative than the resting potential – 70mV to about – 90mV it is called hyperpolarization.

Question 22.
Label the parts of the neuron.
Answer:

A- Nucleus with nucleolus
B- Axolemma
C- Dendrites
D- Myelin sheath, Nucleus
E- Axon (Direction of signal transmission)
F- Node of Ranvier.

Question 23.
The choroid plexus secretes cerebral spinal fluid List the function of it.
Answer:
Cerebrospinal fluid provides buoyancy to the central nervous system.

1. It acts as a shock absorber for the brain and spinal cord.
2. It nourishes the brain cells by transporting food and oxygen.
3. It carries harmful metabolic wastes from the brain to the blood.
4. It maintains constant pressure inside the cranial vessels.

Question 24.
What is the ANS controlling center? Name the parts that are supplied by the ANS?
Answer:
Controlling center – autonomic neural system. Controlling organs.

1. Eyes
2. Salivary Glands
3. Heart
4. Lungs
5. Stomach
6. Liver
7. Kidney
8. Intestines
9. Bladder

Question 25.
Why the limbic system is called the emotional brain. Name the parts of it?
Answer:
The limbic system is a set of components located on both sides of the thalamus present in the inner part of the cerebral hemisphere. It includes the olfactory bulbs, cingulate gyrus, mammillary body, amygdala, hippocampus, and hypothalamus. The limbic system plays a primary role in the regulation of pleasure, pain, anger, fear, sexual feeling, affection, and memory. Hence it is called the emotional brain.

Question 26.
Classify receptors based on the type of stimuli.
Answer:

Receptors	Stimulus	Effector organs
Mechano receptors	Pressure and vibration	Mechano receptors are present in the cochlea of the inner ear and the semicircular canal and utriculus
Chemoreceptors	Chemicals	Taste buds in the tongue and nasal epithelium
Thermo receptors	Temperature	Skin
Photoreceptors	Light	Rod and cone cells of the retina in the eye.

Question 27.
Name the first five cranial nerves, their nature and their functions
Answer:

Cranial nerves	Nature of nerve	Function
I. Olfactory nerve	Sensory	Sense of smell
II.Optic nerves	Sensory	Sense of sight
III. Oculo motor nerves	Motor	Movement of the eye
IV. Trochlear nerve	Motor	Rotation of the eyeball
V.Trigeminal nerve	Sensory and motor mixed	The functioning of face ball

Question 28.
The sense of taste is considered to be the most pleasurable of all senses. Describe the structure of the receptor involved with a diagram.
Answer:

• The sense of taste is considered to be the most pleasurable of all senses.
• The tongue is provided with many small projections called papillae.
• Taste buds are located mainly on the papillae.
• Taste buds are flask-shaped.

There are two major types.

• Gustatory epithelial cells or taste cells.
• Basal epithelial cells or repairing cells.

• Long microvilli called gustatory hairs project from the tip of the gustatory cells and extend through a taste pore to the surface of the epithelium.
• Gustatory hairs are the sensitive portion of the gustatory cells and they have sensory dendrites which send the signal to the brain.
• The basal cells that act as stem cells divide and differentiate into new gustatory cells.

Question 29.
Describe the structures of olfactory receptors?
Answer:
The smell receptors are excited by air-borne chemicals that dissolve in fluids. The yellow coloured patches of olfactory epithelium form the olfactory organs that are located on the roof of the nasal cavity.

The olfactory epithelium is covered by a thin coat of mucus layer below and olfactory glands bounded connective tissues, above. It contains three types of cells: supporting cells, Basal cells and millions of pin-shaped olfactory receptor cells (which are unusual bipolar cells).

The olfactory glands and the supporting cells secrete the mucus. The unmyelinated axons of the olfactory receptor cells are gathered to form the filaments of the olfactory nerve [cranial nerve-I] which synapses with cells of the olfactory bulb.

The impulse, through the olfactory nerves, is transmitted to the frontal lobe of the brain for identification of smell and the limbic system for the emotional responses to odour.

Part-II.

11th Bio Zoology Guide Neural Control and Coordination Additional Important Questions and Answers

I. Choose The Correct Answer

Question 1.
Which of the following acts as a phagocytic cell to engulf the foreign particles at the time of any injury to the brain?
(a) Neuron
(b) Neurilemma
(c) Neuroglia
(d) Axolemma
Answer:
(b) Neurilemma

Question 2.
Name the nutritive cells of neurons.
a) Axon
b) Neuroglia
c) Schwann’s cell
d) Epithelial cells.
Answer:
b) Neuroglia

Question 3.
Which of the following has bipolar neurons?
(a) Intemeurons
(b) Cranial nerves
(c) Spinal nerves
(d) Inner ear
Answer:
(d) Inner ear

Question 4.
Name the plasma membrane which surrounds the neurons?
a) Neurilemma
b) Axolemma
c) Myalin membrane
d) Sarcolemma
Answer:
a) Neurilemma

Question 5.
The interior of the cell of the resting neuron is negative due to ……………….
(a) Greater efflux of Na⁺ outside the cell than, K⁺ influx into the cell.
(b) Only greater efflux of Na⁺ outside the cell.
(c) Greater efflux of K⁺ outside the cell than Na⁺ influx into the cell.
(d) Only greater efflux of K⁺ outside the cell.
Answer:
(c) Greater efflux of K⁺ outside the cell than Na⁺ influx into the cell.

Question 6.
Where are Nissl’s bodies seen in the nerve cell?
a) Cell body and dendrites
b) Cell body and axon
c) Cell body and myelin sheath
d) Cell body and end plate of the axon.
Answer:
a) Cell body and dendrites

Question 7.
When the membrane potential shoots rapidly upto +45 mV, it is called the ………………….
(a) Threshold potential
(b) Spike potential
(c) Repolarization
(d) Hyperpolarization
Answer:
(b) Spike potential

Question 8.
Cell forms the myelin sheath ……………..
a) Schwaan’s cell
b) Neuroglial cells
c) Nephron
d) Epithelial cells
Answer:
a) Schwaan’s cell

Question 9.
The subarachnoid space is present in between ………………..
(a) Piamater and arachnoid mater
(b) Arachnoid mater and duramater
(c) Brain and Piamater
(d) Spinal cord and duramater
Answer:
(a) Piamater and arachnoid mater

Question 10.
Which of the following does the work of phagocytosis of microbes during the infection of the brain
a) Schwann cells
b) Node of Ranvier
c) Neuroglial cells
d) Neurilemma
Answer:
c) Neuroglial cells

Question 11.
Which of the following plays a key role in learning and memory?
(a) Hypothalamus
(b) Pons Varolii
(c) Thalamus
(d) Medulla oblongata
Answer:
(c) Thalamus

Question 12.
Find out the wrong pair
a) Multi polar neuron: One axon and two or more dendrites.
b) Bi polar neurons: One axon and more than two dendrites.
c) Uni polar neurons: Short process axon.
d) Synaptic Knob: Neurotransmitters
Answer:
b) Bi polar neurons: One axon and more than two dendrites.

Question 13.
The reflex action is effected by ……………..
(a) Brain
(b) Medulla oblongata
(c) Effector organs
(d) Spinal cord
Answer:
(d) Spinal cord

Question 14.
Match the following and find the answer.

1. Leakage channels	a. Opens through the sensation of touch and pressure.
2. Ligand-gated channels	b. They are stable.
3. Voltage gated channels	c. Opens through chemical stimulation.
4. Charged particles	d. Ionic channels are always open.

Answer:
c) i- B,ii – D,iii – C,iv – A

Question 15.
Which of the following is produced at the terminal ends of the postganglionic fibres at the effector organs of the parasympathetic neural system?
(a) Noradrenaline
(b) Acetylcholine
(c) Adrenalin
(d) Melatonin
Answer:
(b) Acetylcholine

Question 16.
Where are bipolar neurons situated?
a) Cranial nerves
b) Olfactory lobes of the brain
c) Spinal nerves
d) Skin
Answer:
b) Olfactory lobes of the brain

Question 17.
Which of the following absorbs light to prevent internal reflection in the eye?
(a) Sclera
(b) Retina
(c) Chorid
(d) Cornea
Answer:
(c) Chorid

Question 18.
Find out the odd one.
a) Schwann cell – Myalin sheath
b) Synaptic knob – Synaptic vesicles
c) Bipolar neuron – Cranial nerves
d) Multipolar neuron – Spinal nerves.
Answer:
c) Bipolar neuron – Cranial nerves

Question 19.
The defect hypermetropia can be overcome by using ……………
(a) Concave lens
(b) Convex lens
(c) Cylindrical glass
(d) Surgical procedures
Answer:
(b) Convex lens

Question 20.
Match and find the correct sequence.

I. Neuro junction	a. Neuron which receives a stimulus
II. Presynaptic neurons	b. Synaptic vesicles
III. Synaptic cleft	c. Synapses
IV. Neurotransmitter	d. Pre and post neuron junction

a) I-d II-a II-c IV-d
b) I-a II-c III-d IV-b
c) I-a II-b III-c IV-d
d) I-c II-a III-d IV-b
Answer:
d) I-c II-a III-d IV-b

Question 21.
The olfactory impulses are transmitted to the ……………….. lobe of the brain.
(a) Parietal
(b) Temporal
(c) Occipital
(d) Frontal
Answer:
(d) Frontal

Question 22.
Find out whether the following statements are true or false. Find out the correct sequence.
i. The thick outer covering of the brain is dura matter
ii. The space between pia matter and dura matter is subarachnoid space.
iii. The membrane that surrounds the brain is piamalter
iv. The space between arachnoid and pia mater is subarachnoid space
a) I – False; II – False; III – True; IV – True
b) I-True; II-False; III-True; IV-True
c) I – True; II – False; III – False; IV – True
d) I-True; II-False; III-True; IV-False
Answer:
b) I-True; II-False; III-True; IV-True

Question 23.
Which of the following are present in the fingertips and soles of the feet?
(a) Pacinian corpuscles
(b) Meissner’s corpuscles
(c) Ruffini endings
(d) Krause end bulbs
Answer:
(b) Meissner’s corpuscles

Question 24.
Find out whether the following statements are true or false.
a) At resting membrane potential the efflux of potassium is more than the influx of sodium from the outer surface of the neurilemma.
b) When the stimulus is sent from the cell body to the axon there is no creation of action potential.
c) The spike potential is +45mV.
d) The threshold potential is +55mV.
i) a) True b) True c) False d) False
ii) a) False b) True c) True d) True
iii) a) True b) False c) True d) True
iv) a) True b) False c) True d) False
Answer:
iv) a) True b) False c) True d) False

Question 25.
The protein part of the photopigment is ………………..
(a) Retinal
(b) Opsin
(c) Macula lutea
(d) Fovea centralis
Answer:
(A) Opsin

Question 26.
………………. is the part of the fore-brain.
a) Cerebrum – Mesencephalon
b) Cerebrum – Prosencephalon
c) Cerebrum – Diencephalon
d) Cerebrum – Parietal lobe.
Answer:
c) Cerebrum – Diencephalon

Question 27.
…………………….. is useful in the diagnosis of neurological and sleep disorders.
a) PET
b) CT
c) X – rays
d) EEG
Answer:
d) EEG

Question 28.
Name the structure which connects the cerebral hemisphere
a) Choroid tissue
b) Corpus callosum
c) Neuroglia tissue
d) Pineal body
Answer:
b) Corpus callosum

Question 29.
Match and find out the correct sequence.

I. Frontal lobe	a. Reading
II. Parietal lobe	b. Hearing
III. Temporal lobe	c. Vision
IV. Occipital lobe	d. Memory

a) I-d II-a III-c IV-b
b) I-a II-c III-d IV-b
c) I-a II-b III-c IV-d
d) I-d II-a III-b IV-c
Answer:
d) I-d II-a III-b IV-c

Question 30.
Assertion: Statement A- The cortex of the cerebrum consists of grey matter.
Statement B- The reason for the grey matter is due to the presence of a non – myelinated sheath.
a) Statement A- True, Statement B – False
b) Statement A and B are true
c) Statement A- False the statement B- True.
d) Statement A and B are false.
Answer:
b) Statement A and B are true

Question 31.
Match and find the correct answer.
1. Broca area a. Perception of taste.
2. The pre-central gyrus b. Voluntary movements
3. The postcentral gyrus c. Aggression
4. Amygdala d. Speech function
a) I-a II-b III-c IV-d
b) I-d II-b III-c IV-a
c) I-d II-b Ill-a IV-c
d) I-a II-b III-c IV-d
Answer:
c) I-d II-b III-a IV-c

Question 32.
Assertion: Statement S – Brain controls emotions and feelings.
Statement T – There are no sensory neurons in the brain. Hence it cannot sense the pain.
a) Statement – S – True. Statement T – False
b) Statement – S – True Statement T – True
c) Statement – S – False Statement T – False
d) Statement S – False Statement T – True
Answer:
b) Statement – S – True Statement T – True

Question 33.
Which is considered as the relay centre for impulses
a) Medulla oblongata
b) Cerebrum
c) Hypothalamus
d) Thalamus
Answer:
d) Thalamus

Question 34.
Which indicates A, B, C and D in the following diagram

(a)
a) Temporal lobe
b) Frontal lobe
c) Parietal lobe
d) Cerebellum
(b)
a) Cerebellum
b) Parietal lobe
c) Temporal lobe
d) Frontal lobe
(c)
a) Cerebellum
b) Frontal lobe
c) Temporal lobe
d) Parietal lobe
(d)
a) Parietal lobe
b) Cerebellum
c) Frontal lobe
d) Temporal lobe
Answer:
(b)
a) Cerebellum
b) Parietal lobe
c) Temporal lobe
d) Frontal lobe

Question 35.
Find out the wrong statement.
a) The pre-central gyrus is called a motor strip.
b) The post-central gyrus is called a sensory strip.
c) The medulla oblongata controls respiration.
d) Wernicke area of the brain involved in the comprehension of speech.
Answer:
d) Wernicke area of the brain involved in the comprehension of speech.

Question 36.
The melatonin hormone which controls the sleep-wake cycle is secreted by
a) Pineal body
b) Thalamus
c) Hypothalamus
d) Medulla oblongata
Answer:
a) Pineal body

Question 37.
The lower portion of the midbrain consists of a pair of longitudinal nervous bands called
a) Emotional brain
b) Cerebral peduncles
c) Pons
d) Vermis
Answer:
b) Cerebral peduncles

Question 38.
The cauda equina presents in
a) Cerebrum
b) Thalamus
c) Hippo cambus
d) Spinal cord
Answer:
d) Spinal cord

Question 39.
Match and find the correct answer.
i) Thalamus – A) Respiration Gastric Pits.
ii) Hypothalamus – B) Vision Hearing
iii) Mid brain – C) Satiety centre
iv) Medulla oblongata – D) Learning memory

Answer:
a) i- D, ii – C, iii – B, iv – A

Question 40.
The cluster of nerve tissue in the cell body of neurons are called as
a) Gyri
b) Sulci
c) Vermis
d) Nerve ganglion.
Answer:
d) Nerve ganglion.

Question 41.
Find out the wrong pair
a) Cervical nerve – 8 pairs
b) Thoracic nerve – 12 pairs
c) Sacrum nerve – 4 pairs
d) Coccyx nerve – 1 pair
Answer:
c) Sacrum nerve – 4 pairs

Question 42.
What is the amount of cerebrospinal fluid secreted in an adult?
a) 500 ml
b) 150 ml
c) 400 ml
d) 250 ml
Answer:
b) 150 ml

Question 43.
The dissolved nicotene and alcohol in …………………… and ………………… minutes reach the brain.
a) 7 and 8 minutes
b) 6 and 7 minutes
c) 7 seconds and 6 minutes
d) 7 and 5 minutes.
Answer:
c) 7 seconds and 6 minutes

Question 44.
Name the structure that regulates homeostasis.
a) Mammillary body
b) Pineal body
c) Hypothalamus
d) Pituitary.
Answer:
a) Mammillary body

Question 45.
What is brain stem.
a) The structure seen in between spinal cord and cerebellum.
b) The region between Diencephalon and spinal cord
c) The region between medulla oblongata and cerebrum.
d) The region between medulla oblongata and mid-brain.
Answer:
b) The region between Diencephalon and spinal cord

Question 46.
What is the function of corpora quadri gemina?
a) Vision and hearing
b) Vision and homeostasis
c) Hearing and sense of touch
d) Hearing and vomiting.
Answer:
a) Vision and hearing

Question 47.
The region has seen in the mid of the cerebellum.
a) Corpus callosum
b) Pineal body
c) Pituitary
d) Vermis.
Answer:
d) Vermis.

Question 48.
What is the function of the interneuron?
a) Impulses from afferent and efferent neurons.
b) Impulses transmitted from efferent neurons to afferent neurons.
c) Impulses transmitted from central nervous system to receptor organs
d) From nerve transmitters to the spinal cord
Answer:
a) Impulses from afferent and efferent neurons.

Question 49.
Which part of the brain controls the unconditioned reflux?
a) The cortex of cerebrum
b) The medulla of brain
c) Cerebellum
d) pons.
Answer:
a) The cortex of cerebrum

Question 50.
……………………..pairs of nerves from cranium and …………………….. pairs of nerves from spinal cord.
a) 10 and 31
b) 12 and 31
c) 31 and 12
d) 31 and 10.
Answer:
b) 12 and 31

Question 51.
How much cerebrospinal fluid is synthesized in adults?
a) 200ml
b) 300ml
c) 150ml
d) 100ml.
Answer:
c) 150ml

Question 52.
What is the function of the vagus nerve?
a) It regulates the function of the abdominal structure
b) It regulates the speech and swallowing
c) It regulates the homeostasis of the body
d) Taste perception
Answer:
a) It regulates the function of the abdominal structure

Question 53.
Name the neural system which is auto functioning and self-governed.
a) Somatic neural system
b) Automatic neural system
c) Peripheral neural system
d) Limbic system.
Answer:
b) Automatic neural system

Question 54.
Name the structure that regulates the autonomic neural system.
a) Cerebrum
b) Cerebellum
c) Hypothalamus
d) Pons.
Answer:
c) Hypothalamus

Question 55.
Name the lubricating fluid which is secreted from the gland present at the base of the eyelashes.
a) Lacrymal gland
b) Cerebro-spinal fluid
c) Thymus gland
d) Sebaceous glands.
Answer:
d) Sebaceous glands.

Question 56.
Find the ABC and D in the diagram

a) a) Tear duct b) Sciera c) Iris d) Tear gland
b) a) Sciera b) Iris c) Tear gland d)Tear duct
c) a) Tear duct b) Iris c) Sclerad d)lTear duct
d) a) Tear gland b) Sclera c) Tear duct d) Iris.
Answer:
d) a) Tear gland b) Sclera c) Tear duct d) Iris.

Question 57.
Name the tissue which forms the non-vascular transparent coat cornea
a) Stratified squamous epithelium
b) Squamous epithelium
c) Canal of schlemm
d) All the above.
Answer:
a) Stratified squamous epithelium

Question 58.
Assertion: In bright light, the circular muscle in the iris contract so that the size of the pupil decreases and the light enter is regulated.
Reason: In the dim light, the radial muscle contract the pupil size increases, and less light enters the eye.
a) The assertion true but reason wrong
b) The assertion and reason are true
c) The assertion is true but reason does not explain the assertion
d) The assertion and reason are wrong.
Answer:
a) The assertion true but reason wrong

Question 59.
Name the yellow flat spot at the centre of the posterior region of the retina.
a) Blind spot
b) Scelera
c) Iris
d) Maculalutea
Answer:
d) Maculalutea

Question 60.
Which colour is perceived through chloropsin is sensitive to the medium wavelength of 530 mm
a) Red cones
b) Green cones
c) Blue cones
d) Red cells.
Answer:
b) Green cones

Question 61.
Name the glands that secrete tear.
a) Lacrymal gland
b) Sebaceous gland
c) Mandibular gland
d) Choroid plexues
Answer:
a) Lacrymal gland

Question 62.
…………………… enzyme is present in the tear.
a) Ptyalin
b) Lysozyme
c) Lipase
d) Erypsin.
Answer:
b) Lysozyme

Question 63.
Name the structure where more cones present.
a) Foveacenlralis
b) Maculalutea
c) Retina
d) Blind spot.
Answer:
a) Foveacenlralis

Question 64.
……………………………….. people can see the nearby object but cannot see the distant object.
a) Astigmatism
b) Presbiopia
c) Hypermetropia
d) Myopia
Answer:
d) Myopia

Question 65.
The concave lens helps in correct ………………. defect
a) Myopia
b) Hyper metropia
c) Astigmatism
d) Presbiopia
Answer:
a) Myopia

Question 66.
Which of the defect is depicted in the following diagram:

a) Emmetropia
b) Myopia
c) Hypermetropia
d) Astigmatism.
Answer:
b) Myopia

Question 67.
Match and find the correct sequence.

I. Concave	Surgery
II. Convex	Hypermetropia
III. Cataract	Astigmatism
IV. Cylindrical lens	Myopia

a) 1 -a 2-b 3-c 4-c
b) 1 -d 2-b 3-a 4-c
c) 1-d 2-a 3-a 4-b
d) 1-d 2-c 3-b 4-c
Answer:
b) 1 -d 2-b 3-a 4-c

Question 68.
Name the organ which regulates vision perception and homeostasis.
a) Ear
b) Eye
c) Cerebrum
d) Cerebellum.
Answer:
a) Ear

Question 69.
Find out the wrong pair.
a) Pinna – Eardrum
b) Oval window – Round window
c) Cochlea – Malleus
d) Perilymph – Endolymph
Answer:
c) Cochlea – Malleus

Question 70.
Indicate ABC and D in the Diagram.

a)
a) lncus
b) Eardrum
c) Organ of Corti
d) Tactoreal membrane.
b)
a) Organ of cortri
b) Incus
c) Tectoreal membrane
d)Eardrum
c)
a) Eardrum
b) Incus
c) Organ of Corti
d) Tectoreal membrane
d)
a) Eardrum
b) Incus
c) Tectoreal membrane
d) Organ of Corti
Answer:
d)
a) Eardrum
b) Incus
c) Tectoreal membrane
d) Organ of Corti

Question 71.
Find out the wrong statement.
a) The equilibrium receptor regions called maculae are involved in detecting the linear movement of the head.
b) The otoliths are made up of calcium
c) The crista ampullaris is to detect rotational movement of the head
d) Severe hearing loss occurs with frequent exposure to sound with intensities greater than50db.
(The 90db will affect the hearing).
Answer:
d) Severe hearing loss occurs with frequent exposure to sound with intensities greater than50db.

Question 72.
A person on his way to a village in a car for weekend holidays after finishing the office work. As he is very tired he begins to feel drowsy. He turns up the car stereo volume opens the car window and has sips ice-cold water.
How do these actions keep him awake? The increase in the number of sensory stimuli he received is relayed to the cerebral cortex which gets activated and prevents sleeping,
a) Spinal cord
b) Cerebrum
c) Medulla oblongata
d) Cerebellum.
Answer:
c) Medulla oblongata

Question 73.
Name the structure that connects the middle ear and pharynx.
a) Eustachian tube
b) Middle ear
c) Oval window
d) Organ of the cortii.
Answer:
a) Eustachian tube

Question 74.
Which part of the ear have bony labyrinth and a membranous labyrinth?
a) External ear
b) Inner ear
c) Middle ear
d) None of the above.
Answer:
b) Inner ear

Question 75.
Name the structure present in the bony labyrinth.
a) Cochlea, vestibule, maleus
b) Cochlea, vestibule Incus
c) Cochlea semicircular canals, stapes
d) Cochlea, vestibule semicircular canals.
Answer:
d) Cochlea, vestibule semicircular canals.

Question 76.
Where are the stereo cilia cells present in the ear?
a) Scala media
b) Scala vestibuli
c) Scala tymnani
d) Middle ear.
Answer:
a) Scala media

Question 77.
Match and find the correct sequence.

I. Meissner’s corpuscles	a) continuous pressure
II. Pacinian corpuscles	b) hardness, pain
III. Ruffini endings	c) temperature
IV. Krause and bulbs	d) light pressure

a) I-d, II-a, III-c, IV-d
b) I-d, II-b, III-c, V-a
c) I-d, II-b, Ill-a, IV-c
d) I-a, II-b, III-c, IV-d
Answer:
c) I-d, II-b, Ill-a, IV-c

Question 78.
When a cockroach tries to enter into the ear of a sleeping person, which one of the following process will start?
a) Unconditioned reflex
b) Neuro muscular fatigue
c) Stimulation of negative feedback mechanism
d) conditioned reflex
Answer:
a) Unconditioned reflex

Question 79.
What is the number of nerve cells present in the brain
a) 90 million
b) 100 billion
c) 90 billion
d) 100 million
Answer:
b) 100 billion

(2 Marks)

II. Write Very Short Answer

Question 1.
What are neurons? What are their functions?
Answer:
The structural and functional unit of the nervous system is neurons. They detect, receive, process, and transmit different kinds of stimuli. They are sensory, motor, and autonomic in functions.

Question 2.
What is meant by Neuroglia? What are its functions?
Answer:
The non-nervous special cells called neuroglia from the supporting cells of the nervous tissue.

1. Providing nourishment to the neurons
2. Repairing the injured tissues
3. It helps in dividing and regeneration
4. Acting as phagocyte cells to engulf the foreign particles at the time of any injury to the brain.

Question 3.
Differentiate the functions of myelinated and non-myelinated neurons.
Answer:

Myelinated neuron	Non-myelinated neuron
They conduct impulses rapidly	Conduct impulse slowly
Present in the medulla	Seen in the cortex of the cerebrum.

Question 4.
What are the functions of neuroglia?
Answer:

1. They provide nourishment to the surrounding neurons.
2. They involve in the memory process.
3. They repair the injured tissue due to their dividing and regenerating capacity.
4. They engulf the foreign particles at the time of any injury to the brain.

Question 5.
What is meant by nerve impulses?
Answer:
A nerve impulse is a series of electrical impulses which travel along with the nerve fibre.

Question 6.
What is a neurilemma?
Answer:
The plasma membrane covering the neuron is the neurilemma.

Question 7.
What is meant by threshold potential?
Answer:
During depolarization when enough Na⁺ ions enter the cell the action potential reaches a certain level called threshold potential. (-55 mV)

Question 8.
What are Nodes of Ranvier?
Answer:
The Schwann cells covering the axon are not continuous. There are gaps in the myelin sheath between adjacent Schwann cells. These gaps are called Nodes of Ranvier.

Question 9.
What is meant by all or none principle?
Answer:
The action potential occurs in response to a threshold stimulus but does not occur at sub-threshold stimuli. This is called the all or none principle.

Question 10.
What is Synaptic Cleft?
Answer:
A small gap between the pre and post-synaptic membranes is called Synaptic Cleft. It forms a structural gap and a functional bridge between neurons.

Question 11.
What are meninges?
Answer:
The brain is covered by the outer Duramater, the median Arachnoid mater, and the inner Piamater. These membranes are called meninges.

Question 12.
What is meant by lazy gate?
Answer:
During hyper polarization the K⁺ion gates are more permeable to K⁺ even after reaching threshold level it closes slowly hence called lazy gates.

Question 13.
What is subarachnoid space?
Answer:
The space between the pia mater and arachnoid mater is called subarachnoid space.

Question 14.
What is meant by repolarisation?
Answer:
When the membrane reaches the spike potential the potassium ions K⁺ efflux from the axolemma and hence form negative potential. This is called repolarisation.

Question 15.
What are mammillary bodies?
Answer:
A pair of small rounded body in the hypothalamus is called mammillary bodies. These are involved in olfactory reflexes and emotional response to odour.

Question 16.
Which decides the speed of the conduction of a nerve impulse?
Answer:

• The conduction speed of a nerve impulse depends on the diameter of axon.
• The greater the axon’s diameter the faster is the conduction.

Question 17.
What is septum pellucidum?
Answer:
A thin membrane which separates the lateral ventricles I and II are called the septum pellucidum.

Question 18.
What is the difference between sub durai space and sub arachnoid space
Answer:

Sub durai space	Sub arachnoid space
A narrow sub dural space present in between arachnoid and durameter	The space between the arachnoid membrane and piameter.

Question 19.
What is meant by sulcus and gyrus? What is its functions.
Answer:

• Gyri – The convolution seen in the cerebrum.
• Sulci – The shallow grooves increase the surface area of the cerebral cortex.

Question 20.
What is Choroid plexus?
Answer:
The choroid plexus is a network of blood capillaries found in the roof of the ventricles. These form cerebrospinal fluid from the blood.

Question 21.
What is the function of proca?
Answer:
It involves speech function.

Question 22.
What are Cranial nerves?
Answer:
The 12 pairs of nerves which arise from the brain are called cranial nerves.

Question 23.
Which part of the cerebrum is called a sheet of emotions?
Answer:
The cortex of parietal occipital and temporal.

Question 24.
What is a mixed nerve?
Answer:
A nerve which contains both sensory (afferent) and motor (efferent) fibres is called a mixed nerve.

Question 25.
What are Exteroceptors?
Answer:
Exteroceptors are located at or near the surface of the body. These are sensitive to external stimuli and receive sensory impulses for hearing, vision, touch, taste, and smell.

Question 26.
Where is the pineal body situated? What are its functions?
Answer:
It is situated behind the choroid plexus the epithalamus forms a short stalk
Functions: The melotoxin secreted by the pineal body regulates the sleep wake cycle.

Question 27.
What are Lacrymal glands?
Answer:
Tears secreting glands located in the upper lateral region of each orbit are called Lacrymal glands.

Question 28.
What is meant by corpus callosum?
Answer:
The two hemispheres of the cerebrum are connected with the nerve band known as the corpus callosum.

Question 29.
What is meant by brain stem? What are its parts?
Answer:
The region between the spinal cord and diencephalon.

1. Mid-brain
2. Pons varoli
3. Medulla oblongata

Question 30.
What is meant by corpora quadri gemina? What are its functions?
Answer:

• The four papillae are seen on the dorsal side of mid brain.
• Perception of vision and hearing

Question 31.
What is macula lutea?
Answer:
The yellow flat spot at the centre of the posterior region of the retina is called macula lutea. It is responsible for sharp detailed vision.

Question 32.
What are the functions of the cerebellum?
Answer:
The cerebellum controls and coordinates muscular movements and body equilibrium.

Question 33.
What is meant by receptors?
Answer:
The organ which made us aware of changes occur in our surrounding is called receptors.

Question 34.
What is meant by a voluntary neural system?
Answer:
It is the part of the peripheral neural system associated with the voluntary control of body movements via skeletal muscles

Question 35.
Name the bacteriocidal substance present in the tears? Where is it seen? Name its secretion?
Answer:

• Lysosome enzyme
• Seen in tears.
• Lacrymal glands. 1ml is secreted in a day.

Question 36.
What is crista ampullaris?
Answer:
The lower end of each semicircular canal is swollen and it is called the ampulla. Each ampulla has a sensory area known as crista ampullar.

Question 37.
What are cerebral peduncles?
Answer:
The region between the diencephalon and the pons is called the midbrain. It consists of a pair of longitudinal bands of nervous tissue called cerebral peduncles.

Question 38.
What is a brain stem? What are its parts?
Answer:
It is the part of the brain between the spinal cord and the diencephalon.
Organs: Mid-brain, Pons, Medulla oblongata

Question 39.
What are Krause end bulbs?
Answer:
These are thermoreceptors of the skin that sense temperature.

Question 40.
Where is the enlargement region seen in the spinal cord?
Answer:

• Cervical enlargement
• Lumbar enlargement.

Question 41.
What is meant by reflex action?
Answer:

• When a very quick response is needed the spinal cord can effect motor initiation as the brain and brings about an effect.
• This rapid action by the spinal cord is called reflex action.

Question 42.
What is meant by the peripheral nervous system?
Answer:
All nervous tissue outside the CNS is the nervous system.

Question 43.
What is meant by mixed nerve?
Answer:
Each spinal nerve is a mixed nerve containing both afferent (sensory) and efferent (motor) fibers.

Question 44.
What is meant by pre ganglionic neuron?
Answer:
Its cell body is in the brain or spinal card. Its myelinated axon exits the CNS as part of cranial or spinal nerve and end in an autonomic ganglion.

Question 45.
What is autonomic ganglion?
Answer:
The axons of pre ganglionic neuron and cell bodies of post ganglionic neuron includes autonomic ganglion.

Question 46.
What is post ganglionic neuron?
Answer:
It conveys nerve impulses from autonomic ganglia to visceral effector organs.

Question 47.
What are the two branches of the autonomous nervous system?
Answer:

1. Sympathetic neural system
2. Parasympathetic neural system.
3. varying distances is called accommodation.

Question 48.
Give short notes on Lacrymal glands?
Answer:

• The tear secreting glands are known as Lacrymal glands.
• 1ml of tear is secreted in a day.
• Tear salts, mucous and lysozyme enzyme to destroy bacteria.

Question 49.
What is conjunctiva?
Answer:
It is a thin protective mucous membrane found lining the outer surface of the eye ball.

Question 50.
Dilation and congestion of the blood vessels due to local irritation or infections. What is the disease? When will it occur?
Answer:

• Conjunctivitis or madras eye.
• Irritation or infection are the cause of bloodshot eye.

Question 51.
What is sty?
Answer:
Infection of ciliary glands by bacteria causes painful pus-filled swelling called a sty.

Question 52.
What are the three types of cells present in the neural retina?
Answer:

• Photo receptor cell
• Cones
• Rods
• Bipolar and ganglion cells.

Question 53.
What is a cataract?
Answer:
Due to the changes in nature of protein the lens become an opaque called cataract.

Question 54.
What is aqueous humour and vitreous humour
Answer:

• Aqueous humour – The fluid filled in between the cornea and iris.
• Vitreous humour – Fluid filled in between lens and retina.

Question 55.
Give notes on lens fibres?
Answer:
Eye lens is transparent and biconvex made up of long columnar epithelial cells called lens fibre, these cells are formed of crystalline protein.

Question 56.
What are the three layers of eyeball?
Answer:

1. Sclera – Outer coat
2. Choroid – Pigmented middle layer
3. Retina – Inner most layer

Question 58.
What is meant by maculae lutea?
Answer:
The yellow flat spot at the centre of the posterior region of the retina is called macula lutea. It is responsible for sharp detailed vision.

Question 59.
What is fovea centralis?
Answer:
A small depression present in the centre of the yellow spot is called fovea centralis which contains only cones.

Question 60.
What is a blind spot?
Answer:
The optic nerves and the retinal blood vessels enter the eye slightly below the posterior pole whichis devoid of photoreceptors is called a blind spot.

Question 61.
Why there is no cornea rejection during cornea transplantation?
Answer:

• There is little or no possibility of cornea rejection.
• This is because the cornea does not have blood vessels.

Question 62.
What are the three ear ossicles?
Answer:

1. Malleus – hammer bone
2. Incus – anvil bone
3. Stapes – stirrup bone

Question 63.
What are the three chambers of cochlea?
Answer:

1. Scala vestibule
2. Scala tympani
3. Scala media

Question 64.
What is tectorial membrane?
Answer:
A roof-like structure over hanging the organ of Corti throughout its length with the stiff gel membrane called tectorial membrane.

Question 65.
Name the receptors which are excited by airborne chemicals that dissolve in fluids?
Answer:
The receptors for taste and smell are the chemo receptors

Question 66.
What is a tactile Merkel disc?
Answer:
It is the light touch receptor lying in the deeper layer of the epidermis.

Question 67.
What are the structures present in the membranous labyrinth?
Answer:

• Cochlea
• Vestibule
• Semi circular canals

Question 68.
What are the three chambers of cochlea? Name the membrane which separates these chambers?
Answer:

1. Scala vestibuli
2. Scala tympanii
3. Scala media

Separating membranes
Reisner’s membrane. It separates scala vestibuli from scala media
Basilar membrane. It separates scala media from scala tympani.

Question 69.
What is meant by stereo cilia?
Answer:

• The organ of corti contains numerous hair cells on the basilar membrane.
• Protruding from the apical part of each hair cell is hair-like structures called stereo cilia.

Question 70.
What is proprioception?
Answer:
The ability to provide information about the position and movements of the body is proprioception.

Question 71.
What is meant by vestibular system?
Answer:
This is the organ of balance this system is composed of fluid-filled sacs and tubules.

Question 72.
Give notes on utriculus and sacculus?
Answer:
The utricle and saccule contain equilibrium receptor regions called maculae that are involved in detecting the linear movement of the head.

Question 73.
What is otolith?
Answer:

• Maculae contains hair cells. These hair cells contain calcareous particles called otoliths.
• It increases the inertia.

Question 74.
What are ampullae?
Answer:
At one end of each semicircular canal at its lower end has a swollen area called ampulla Each ampulla has sensory hair cells and supporting cells called crista ampullaris. The function is to detect the rotational movement of the head.

Question 75.
Give the name of balancing structures which perform the following action.

• Linear movement of the head
• Changes occurring in body position.
• Rotational movement of the head

Answer:

• Maculae
• Vestibular system
• Crista ampularis

Question 76.
What is the unit of sound? Give notes on our ability of sound perception?
Answer:

• The intensity of sound is measured in decibels. (dB)
• 0-50 dB is the threshold of hearing for normal ear.
• Prolonged exposure to sound with intensities greater than 90dB causes hearing loss.

Question 77.
What are chemo receptors?
Answer:

• The receptors for taste and smell are the chemo receptors
• The smell receptors are excited by air borne chemicals that dissolve in fluids.

Question 78.
What are olfactory organs? Where are they situated?
Answer:

• The yellow coloured patches of olfactory epithelium form the olfactory organs.
• They are located on the roof of the nasal cavity.

Question 79.
What are papillae?
Answer:
The tongue is provided with many small projection called papillae which is responsible for taste.

Question 80.
Give notes on taste buds.
Answer:

• The taste bud cells are subjected to huge amounts of friction because of their location and are routinely burned by hot foods.
• These are the most dynamic cells in the body and replaced every seven to ten days.

 

(3 Marks)

III. Short Answers

Question 1.
What are the three main functions of nervous system.
Answer:

• Sensory functions: It receives sensory input from internal and external environment.
  Motor functions: It transmits motor commands from the brain to the skeletal and muscular system.
• Autonomic functions: Reflex actions.

Question 2.
How do we classify neurons on the basis of its functions.
Answer:

• Afferent neurons – That take sensory impulses to the central nervous system from the sensory organs.
• Efferent neurons – That carry motor impulses from CNS to the effector organ.
• Inter neurons – That lie entirely within the CNS between the afferent and efferent neurons.

Question 3.
What is meant by depolarisation?
Answer:

• The inside of the axolemma becomes positively charged and negatively charged outside.
  This reversal of electrical charge is called depolarisation.

Question 4.
How are nerve impulses transmitted?
Answer:

• Inner to the axolemma the cytoplasm contains the infra cellular fluid with large amounts of potassium and magnesium phosphate with negatively charged proteins and other organic molecules.
• Outside the axolemma contains large amounts of sodium chloride bicarbonates CO² and metabolic wastes
• Due to the charged particles present in the inner and outside of the axolemma are responsible for the conduction of nervous impulses.

Question 5.
What is meant by repolarisation?
Answer:

• When the axolemma reaches the spike potential the sodium voltage – gate closes and potassium – voltage gate opens.
• It checks influx of Na⁺ ions and initiation the efflux of K ions which lowers the number of positive ions within the cell. Thus the potential falls back towards the resting potential.

• The reversal of membrane potential inside the axolemma to negative occurs clue to efflux of K⁺ ions. This is called repolarisation.

Question 6.
What is meant by hyper polarisation?
Answer:

• If repolarisation becomes more negative than the resting potential -70 mV to about -90 mV.
• It is called hyper polarisation. During this K⁺ ion, gate is more permeable to K⁺ even after reaching the threshold level as it closes slowly hence called lazy gates.

• The membrane potential return to its original resting state when K⁺ ion channel close completely.
• During hyper polarization the Na⁺ voltage gate remains closed.

Question 7.
Give an account of the conduction speed of a nerve impulse.
Answer:

• If the axon’s diameter is greater the conduction will be faster.
• The myelinated axon conducts the impulse faster than the non-myelinated axon.

Question 8.
What is meant by saltatory conduction?
Answer:
The myelinated axon conduction the impulse faster than the non – myelinated axon.
The voltage gated Na⁺ and K⁺ channels are concentrated at the nodes of Ranvier as a result the impulse jumps from node to node. This is called saltatory conduction.

Question 9.
Give an account of the membranes (meninges) of brain?
Answer:
Brain is covered by three cranial meninges.

1. The outer thicker layer is duramater which lines the inner surface of the cranial cavity.
2. The inner most layer which is adhered to the brain is the piameter.
3. The median thin layer is arachnoid mater by a narrow subdural space.
4. The piameter is separated from the arachnoid mater by the subarachnoid space.

Question 10.
List out the functions of brain lobes?
Answer:

Structure	Function
Frontal	Behaviour intelligence memory movement
Parietal	Language reading sensation
Temporal	Speech hearing memory
Occipital	Visual processing

Question 11.
Why is thalamus considered as a important relay centre for impulse?
Answer:

• It serves as a relay centre for impulses between the spinal and brain and cerebrum.
• Information is sorted and edited.
• It plays a key role in learning and memory.
• It is a co-ordinating centre for sensory and motor signaling.

Question 12.
Why there may be a death due to the affectation of medulla oblongata?
Answer:

• Medulla controls cardio-vascular reflexes respiration and gastric secretions.
• If medulla is getting affected the circulation and respiration is affected.
• That may cause a death of a person.

Question 13.
Give notes on mid brain?
Answer:

• The midbrain is located between the diencephalon and the pons.
• The lower portion of the mid-brain consists of a pair of longitudinal bands of nervous tissue called cerebral peduncles.
• This relay impulses back and forth between cerebrum cerebellum pons and medulla.
• The dorsal position of the mid Brain consist of four rounded bodies called corpora quadrigemina which acts as a reflex center for vision and hearing.

Question 14.
What are the features we develop when there is a functional deficiency of serotonin and nor epinephrine?
Answer:
Features:

• negative mood
• loss of interest
• an in ability to experience pleasure
• suicidal tendencies.

Drugs:
Anti depressant drug can treat all this features.

Question 15.
Give notes on cerebro spinal fluid?
Answer:

• 150ml of cerebro spinal fluid is secreted in an adult.
• 500ml of cerebro spinal fluid is secreted in a day.
• Every 8 hours this fluid is rejuvenated.
• The choroid plexus carries harmful metabolic wastes from the brain to the blood.

Question 16.
Based on their position how the receptors are classified?
Answer:
1. Exteroceptors: They are located at the surface of the body.
These senses the hearing vision touch taste and smell.

2. Introceptors: They are located in the visceral organs and blood vessels.
They are sensitive to internal stimuli.

3. Prerprioceptors:
They provide information about position and movements of the body.

Question 17.
Your friend is returning home after his visit to USA. All at home are waiting for his arrival.
How would you feel? State the division of ANS that predominates and mention few changes take place in your body?
Answer:

• The sympathetic and parasympathetic neural system are is mainly involved.
• On seeing his friend out of the happiness his autonomic nervous system is stimulated and he gets tears in his eyes.
• After sometime the parasympathetic stops the secretion of tears.

Question 18.
What is meant by depression? What are its symptoms?
Answer:

• Depression is a functional deficiency of serotonin and nor epinephrine.
• This disorder is characterized by a pervasive negative mood, loss of interest an inability to experience pleasure and suicidal tendencies.

Question 19.
When dust falls on our eyes like eyelids close immediately not waiting for our willingness, on touching a hot pan the hand is with drawn rapidly. Do you know how this happens?
Answer:
Reflex axon.
When a very quick response is needed the spinal cord can effect motor initiation as the brain and brings about an effect it is due to fast action of spinal cord.

Question 20.
What are the differences between conditioned and unconditioned reflex.
Answer:

Unconditioned reflex	Conditioned reflex
In born reflex for an unconditioned stimulus.	It’s response to a stimulus acquired by learning.
It does not need any past experience or training	Does not naturally exists in animals.
Eg: Blinking of an eye when a dust particle about to fall in it	Eg: Excitement of salivary gland on seeing a food

Question 21.
What is the difference between exteroceptors and interoceptors.
Answer:

Exteroceptors	Interoceptors
Located at or near the surface of the body	They are located in the visceral organs and blood vessels.
These receive impulses from hearing vision touch taste and smell.	They are sensitive to internal stimuli.

Question 22.
Where are lens fiber seen? What is the substance that fills it?
Answer:

• The lens is a transparent biconvex structure made up of slender columnar epithelial cells.
• These cells are called as lens fibre.
• These cells are formed of crystaline protein.

Question 23.
What is meant by accommodation of eye? List the structures that are involved in this process?
Answer:

• The ability of the eyes to focus objects at varying distances is called accommodation.
• This is achieved by suspensory ligament ciliary muscle and ciliary body

Question 24.
Name the structures that helps in fixing eyes in the eye ball?
Answer:
Eye is held in its position with the help of six extrinsic muscles. They are

• Superior
• Interior
• Lateral
• Median rectus muscle
• Superior oblique
• Inferior oblique

Question 25.
Name the accessory structure which protects eye?
Answer:

• Eye lashes and the eye brows
• They help to protect the eyeballs from foreign objects, perspiration and from direct sunrays.
• Sebaceous glands or ciliary glands.
• They secrete a lubricating fluid.
• Lacrymal glands.
• Secrete tears.
• Tears contain salts mucus and lysozyme enzyme to destroy bacteria.

Question 26.
Give an account of aqueous humour?
Answer:

• It supplies nutrients and oxygen to the lens cornea and retinal cells.
• It is produced and drained at same rate.
• It maintains a constant infra ocular pressure of about 16 mmHg.

Question 27.
Give short notes on glaucoma.
Answer:
Any block in the canal of Schlemm increases the intra ocular pressure of aqueous humour and leads to “glaucoma when the optic nerve and the retina are compressed due to pressure.

Question 28.
Name the detects of detraction.
Answer:

• Myopia
• Hyper metropia
• Astigmatism
• Cataract

Question 29.
Give notes on pigments of colour vision
Answer:

• Redcones. It contains visual pigment erythropsin which is sensitive to long wavelength close to 560 nm.
• Green cones – It has a pigment chloropsin which is sensitive to medium wavelength of 530 nm.
• Blue cones – It has a pigment which is sensitive to short wavelength of 420 nm.

Question 30.
What is the difference between conducting hearing loss and neuro-sensory hearing loss?
Answer:

Conducting Hearing loss	Neuro sensory
This defect is due to the blockage of ear canal with ear wax	The defect may be in the organ of cortii
Rupture of ear	The auditory nerve
Middle ear infection with fluid accumulation restriction of ossicular movement	In the ascending auditory pathways or auditory cortex

Question 31.
Give short notes on melanin.
Answer:

• Melanocytes synthesize melanin.
• It gives colour to skin and protects it from the sun.
• Vitiligo is a condition in which the melanin pigment is lost from the areas of the skin causing white patches.
• The leukoderma appears when melanocytes fails to synthesis melanin pigment.

Question 32.
What is meant by the proprioception?
Answer:

• Balance is part of a sense called proprioception.
• It is the ability to sense the position orientation and movement of the body.

Question 33.
Which is the fastest renewable cells in the body? How is it affected?
Answer:
Taste buds

• Taste buds are subjected to huge amounts of friction because of their location and are routinely burned by hot foods.
• These cells are replaced every 7-10 days.

Question 34.
Name the disease which can affect people of any age gender or ethnic group. This is not the contagious disease?
Answer:
Leucoderma is a condition in which the melanin pigment is lost from areas of the skin causing white patches.

Question 35.
What are meissner’s corpuscles?
Answer:

• These are small light pressure receptors found just beneath the epidermis in the dermal papillae.
• They are numerous in hairless skin areas such as finger tips and soles of the feat.

(5 Marks)

IV. Brief Answers

Question 1.
Describe structure of a neuron.
Answer:
Neuron is composed of three region.

1. Cell body
2. Dendrites
3. axon.

Cell body:
The cell body is spherical. There is no centriole.
The plasma membrane covering the neuron is called neurilemma and axon is axolemma.

Dendrites:
The repeatedly branched short fibres coming out of the cell bod dendrites which transmit impulses towards the cell body in it’s cytoplasm Nissl’s granules are present.

Axon:
It is a long fibre that arises from a cone shaped area of the cell body. There is no golgi bodies and Nissis granules in its cytoplasm.
The axon of peripheral nerves is surrounded by Schwann’s cells to form myelin sheath. The myelin sheath is not continuous. There are gaps in the myelin sheath between an adjacent Schwann cells called nodes of Ranvier.
Each branch at the distal end of the axon terminates into a knob like structure called synaptic knob which possesses synaptic vesicles filled with transmitters. The axon transmits nerve impulses away from the body to neuro muscular junction. The myelinated nerve cell transmits impulses faster than non – myelinated nerve cells.

Question 2.
Describe about the different types of neuron with diagram?
Answer:
1. Multi polar neurons:
They have many processes with one axon and two or more dendrites.

2. Bipolar neurons:
They have two processes with one axon and one dendrites.
These are found in the retina of the eye, inner ear and the olfactory area of the brain.

3. Unipolar neurons:
They have a single short process and one axon.

Question 3.
Give an account of Ionic channels in the axolemma?
Answer:
Ionic channels:

1. Leakage channels
2.  Ligand – gated channels
3. Voltage-gated channels.

1. Leakage channels:

• • These channels are always remain open.
  • K⁺ leakage channels are more in number than the Na⁺ leakage channels.
  • Sarco lemma has greater permeability to k⁺ icons than Na⁺ icons
  • These icons keep moving continuously to maintain the potential continuously to maintain the
  • potential difference across the axo lemma.

2. Ligand – gated channels:
These are chemic called gated channels which open or close in response to a chemical stimuli.

• They are located between the pre synaptic membrane of the first axon and post synaptic membrane of the second.
• The neurotransmitter acetylcholine opens ligand channels that allow Na⁺ and Ca⁺⁺ ions diffuse inward and K⁺ icon diffuse outward.

Voltage-gated channels:
Answer:
This channels open in response to a physical stimulus in the form of vibration such as touch and pressure.

• Sodium Voltage gated channels.
• Potassium Voltage gated channels.

Question 4.
Explain the transmission of nerve impulses?
Answer:
The transmission of impulse involves two main phases; Resting membrane potential and Action membrane potential. Resting membrane Potential: The electrical potential difference across the plasma membrane of a resting neuron is called the resting potential during which the interior of the cell is negative due to greater efflux of K⁺ outside the cell than Na⁺ influx into the cell.

When the axon is not conducting any impulses i.e. in resting condition, the axon membrane is more permeable to K⁺ and less permeable to Na⁺ ions, whereas it remains impermeable to negatively charge protein ions. The axoplasm contains high concentration of K⁺ and negatively charged proteins and low concentration of Na⁺ ions.

In contrast, fluid outside the axon (ECF) contains a low concentration of K+ and a high concentration of Na+, and this forms a concentration gradient. This ionic gradient across the resting membrane is maintained by ATP driven Sodium-Potassium pump, which exchanges 3Na+ outwards for 2K+ into the cells.

In this state, the cell membrane is said to be polarized. In neurons, the resting membrane potential ranges from -40 mV to -90 mV, and its normal value is -70 mV. The minus sign indicates that the inside of the cell is negative with respect to the outside.

Action membrane potential:
An action potential occurs when a neuron sends information down an axon, away from the cell body. It includes the following phases, depolarization, repolarization, and hyperpolarization.

Depolarization – Reversal of polarity:
When a nerve fibre is stimulated, sodium voltage-gated opens and makes the axolemma permeable to Na+ ions; meanwhile the potassium voltage-gated closes. As a result, the rate of flow of Na⁺ ions into the axoplasm exceeds the rate of flow of K⁺ ions to the outside fluid [ECF]. Therefore, the axolemma becomes positively charged inside and negatively charged outside.

This reversal of electrical charge is called Depolarization. During depolarization, when enough Na⁺ ions enter the cell, the action potential reaches a certain level, called threshold potential [-55 mV], The particular stimulus which is able to bring the membrane potential to the threshold is called threshold stimulus.

The action potential occurs in response to a threshold stimulus but does not occur at subthreshold stimuli. This is called the all or none principle. Due to the rapid influx of Na⁺ ions, the membrane potential shoots rapidly up to + 45 mV which is called the Spike potential.

Repolarisation [Falling Phase]: When the membrane reaches the spike potential, the sodium voltage-gated closes, and the potassium voltage-gated opens. It checks influx of Na⁺ ions and initiates the efflux of K⁺ ions which lowers the number of positive ions within the cell.’Thus, .the potential falls back towards the resting potential. The reversal of membrane potential inside the axolemma to negative occurs due to the efflux of K+ ions. This is called Repolarisation.

Hyperpolarization:
If repolarization becomes more negative than the resting potential -70 mV to about -90 mV, it is called Hyperpolarization. During this, K⁺ ion gates are more permeable to K+ even after reaching the threshold level as it closes slowly; hence called Lazy gates. The membrane potential returns to its original resting state when K⁺ ion channels close completely. During hyperpolarization, the Na⁺ voltage gate remains closed.

Conduction Speed of a nerve impulse: The conduction speed of a nerve impulse depends on the diameter of axon. The greater the axon’s diameter, the faster is the conduction.. The myelinated axon conducts the impulse faster than the non-myelinated axon.

The voltage-gated Na⁺ and K⁺ channels are concentrated at the nodes of Ranvier. As a result, the impulse jumps node to node, rather than traveling the entire length of the nerve fibre. This mechanism of conduction is called Saltatory Conduction. Nerve impulses travel at the speed of 1-300 m/s.

Question 5.
a) What is meant by action – membrane potential?
b) What is Depolarisation?
Answer:
a) An action potential occurs when a neuron sends information down an axon away from the cell body.
b) When a nerve fibre is stimulated sodium voltage gate opens and makes the axo lemma permeable to Na⁺⁺ and the potassium voltage gate closes and potassium is getting out of the axo lemma. The concentration reduces

• The axo lemma becomes positively charged inside and negatively charged outside.
• This reversal of electrical charge is called depolarisation potential reaches level called threshold potential (-55mV)
• The stimulus which bring this threshold potential is called threshold stimulus.
• The action potential occur in response to a threshold stimulus but does not occur at subthreshold stimuli. This is called all or none principle.
• Due to the rapid influx of Na⁺ ions the membrane potential shoots rapidly up to +45mV which is called the spike potential.

Question 6.
What is synapsis?
Answer:

• The junction between two neurons is called a synapses through which a nerve impulse is transmitted,
• The first neuron involved in the synapse forms the pre synaptic neuron and the second neuron is the post – synaptic neuron
• A small gap between the two neuron is synaptic cleft.
• The axon terminals contain synaptic vesicles filled with neurotransmitters.
• When an impulse arrives at the axon terminals it depolorizes the pre – synaptic membrane opening the voltage gated calcium channels.
• Influx of calcium ions stimulates the synaptic vesicles toward the pre – synaptic membrane and fuse with it.
• In the neurilemma the vesicles release their neurotransmitters into the synaptic cleft by exocytosis.
• The released neurotransmitters bind to their specific receptors.
• The entry of the ions can generate a new potential in the post synaptic neuron.
• This excitatory post – synaptic potential causes depolarisation and in inhibitory post – synaptic potential causes hyperpolarisation.

Question 7.
In the following diagram indicate
Answer:
(A) – Frontal
(B) – parietal
(C) – occipital
(D) – temporal lobe

Question 8.
Describe the structure of human brain with a diagram?
Answer:

• The brain is located in the cranial cavity and it is covered by three cranial membranes.
• The outer layer — durameter the inner most layer piameter and the median thin layer arachnoid. The brain is divided into three major regions. Fore brain, Mid-brain, Hind

• It comprises of cerebrum and diencephalon.
• Tire cerebral cortex is composed of grey and unmyelinated nerve cells.
• The medulla is composed of white mater.
• The surface of the cerebrum shows many convolutions and grooves. The folds are called gyri and the shallow groove is sulci.

There are eight lobes in cerebrum.
A pair of frontals, parietals temporals and occipital lobes.
The longitudinal fissure divides the cerebrum longitudinally into two hemispheres The hemispheres are connected by a tract of nerve fibres called corpus callosum.
Cerebral cortex has three functional areas

Sensory areas:
It occurs in the parietal temporal and occipital lobes of the cortex.

Motor areas:
This controls voluntary muscular movement which lies in the posterior part of the frontal iobes.

Association area:
It lies in between cortex and diencephalan This involves in memory communication learning and reasoning.

Question 9.
Explain the structure of the forebrain?
Answer:
The forebrain comprises the following regions: Cerebrum and Diencephalon. The cerebrum is the ‘seat of intelligence’ and forms the major part of the brain. The cerebrum consists of an outer cortex, inner medulla and basal nuclei.

The superficial region of the cerebrum is called the cerebral cortex, which looks grey due to the presence of unmyelinated nerve cells. Cerebral cortex – consists of the neuronal cell body, dendrites, associated glial and blood vessels.

The surface of the cerebrum shows many convolutions (folds) and grooves. The folds are called gyri, the shallow grooves between the gyri are called sulci and deep grooves are called fissures. These sulci and gyri increase the surface area of the cerebral cortex. Several sulci divide the cerebrum into eight lobes; a pair of frontals, parietals, temporals and occipital lobes.

A median longitudinal fissure divides the cerebrum longitudinally into two cerebral hemispheres. A transverse fissure separates the cerebral hemispheres from the cerebellum.

The hemispheres are connected by a tract of nerve fibres called corpus callosum. Cerebral cortex has three functional areas namely sensory areas occur in the parietal, temporal and occipital lobes of the cortex. They receive and interpret the sensory impulses.

Motor area of the cortex which controls voluntary muscular movements lies in the posterior part of the frontal lobes. The areas other than sensory and motor areas are called Association areas that deal with integrative functions such as memory, communications, learning and reasoning. Inner to the cortex is medulla which is white in colour and acts as a nerve tract between the cortex and the diencephalon.

Diencephalon consists largely of following three paired structures. The epithalamus forms the roof of the diencephalon and it is a non-nervous tissue. The anterior part of the epithalamus is vascular and folded to form the choroid plexus. Just behind the choroid plexus, the epithalamus forms a short stalk that ends in a rounded body called pineal body which secretes the hormone, melatonin which regulates the sleep and wake cycle.

Thalamus is composed of grey matter which serves as a relay centre for impulses between the spinal cord, brain stem and cerebrum. Within the thalamus, information is sorted and edited and plays a key role in learning and memory. It is a major coordinating centre for sensory and motor signaling.

Hypothalamus forms the floor of the diencephalon. The downward extension of the hypothalamus, the infundibulum connects the hypothalamus with the pituitary gland. The hypothalamus contains a pair of small rounded body called mammillary bodies that are involved in olfactory reflexes and emotional responses to odour.

Hypothalamus maintains homeostasis and has many centres which control the body temperature, urge for eating and drinking. It also contains a group of neurosecretory cells which secrete the hypothalamic hormones. Hypothalamus also acts as the satiety centre.

Limbic system: The inner part of the cerebral hemisphere constitutes the limbic system. The main components of limbic system are olfactory bulbs, cingulate gyrus, mammillary body, amygdala, hippocampus and hypothalamus.

The limbic system is called the ‘emotional brain’ because it plays a primary role in the regulation of pleasure, pain, anger, fear, sexual feeling and affection. The hippocampus and amygdala also play a role in memory. Brain stem is the part of the brain between the spinal cord and the diencephalon. It consists of mid-brain, pons varolii and medulla oblongata.

Question 10.
Describe the structures of diencephalon?
Answer:
Epithalamus:

• It is a non – nervous tissue.
• The anterior part of epithalamus is vascular and folded to form the anterior choroid plexus.
• The epithalamus forms a short stalk which ends in a rounded body called pineal body.
• This secretes the hormone melotonin which regulates sleep and wake cycle.

Thalamus:

• It is formed of grey matter
• It serves as a relay centre for impulses between the spinal cord brain stem and cerebrum.
• It plays a key role in learning and memory.
• It is a major co-ordinating centre for sensory and motor signalling.

Hypothalamus:

• It forms the floor of the diencephalon.
• It has a pair of small rounded body called mammillary bodies
• It involves in olfactory reflexes and emotional responses to odour.
• It maintains homeostasis.
• It controls the body temperature.
• Urge for eating and drinking.
• It also contains a group of neuro secretory cells which secrete the hypothalamic hormones.
• It also acts as the satiety centre.

Question 11.
Explain the structure of the Hindbrain?
Answer:
Rhombencephalon forms the hindbrain. It comprises of cerebellum, pons varolii and medulla oblongata. The cerebellum is the second largest part of the brain. It consists of two cerebellar hemispheres and a central worm-shaped part, the vermis. The cerebellum controls and coordinates muscular movements and body equilibrium. Any damage to the cerebellum often results in uncoordinated voluntary muscle movements.

Pons varoli lies in front of the cerebellum between the midbrain and the medulla oblongata. The nerve fibres in the pons varolii form a bridge between the two cerebellar hemispheres and connect the medulla oblongata with the other region of the brain. The respiratory nuclei found in the pons cooperate with the medulla to control respiration.

Medulla oblongata forms the posterior-most part of the brain. It connects the spinal cord with various parts of the brain. It receives and integrates signals from spinal cord and sends it to the cerebellum and thalamus. Medulla contains vital centres that control cardiovascular reflexes, respiration and gastric secretions.

Question 12.
Differentiate the conditioned stimulus from unconditioned stimulus.
Answer:

Conditioned	Unconditioned
1. Not through learning	Acquired by learning
2. In born reflex	It is not an in born reflex
3. It does not need any past experience	Experience makes it a part of the behaviour
4. Eg: Blinking of an eye when a dust fall in to it.	Eg: Secretion of salivary gland on seeing the food

Question 13.
Tabulate the nerves and functions and its nature of 6-12th cranial nerves.
Answer:

Cranial nerves	Nature of nerve	Function
I Olfactory nerve	Sensory	Sense of smell
II Optic nerve	Sensory	Sense of sight
III Oculomotor nerve	Motor	Movement of the eye
IV Trochlear nerve	Motor	Rotation of the eye ball
V Trigeminal nerve	Sensory and motor (mixed)	Functioning of facial parts
VI Abducens nerve	Motor	Rotation of the eye ball
VII Facial nerve	Mixed	Functioning of facial parts
VIII Auditory/ Vestibulocochlear nerve	Sensory	Maintains the equilibrium of the body/ Auditory function
IX Glossopharyngeal nerve	Mixed	Taste and touch
X Vagus	Mixed	Regulation of the visceral organs
XI Spinal accessory	Motor	Muscular movement of pharynx, larynx, neck and shoulder
XII Hypoglossal	Motor	Speech and swallowing

Question 14.
Tabulate the functions of sympathetic and para sympathetic nerve.
Answer:

Sympathetic nervous system	Para sympathetic nervous system
1. It dialates pupil	It constricts pupil of the eye
2. It inhibits the secretion of saliva	It stimulates saliva secretion
3. It increases the heart beat	It reduces the heart beat
4. It dialates bronches	It constricts the bronchus
5. It inhibits digestion	It stimulates digestion
6. It increases the glucose release	It stimulates bile release
7. Stimulates epinephrine and nor epinephrine release	It reduces the epinephrine and nor epinephrine release
8. Inhibits peristalsis and secretion	Stimulates peristalsis and secretion
9. Reflexes bladder	Contracts bladder

Question 15.
Describe the structure of the cross-section of spinal cord.
Answer:

• There are two indentations the posterior median sulcus and the anterior median fissure.
• In the spinal cord the grey matter forms an inner butterfly-shaped region surrounded by the outer white matter.
• The grey matter consists of dendrites inter neurons and guai cells.
• White matter consists of bundles of nerve fibres.
• Each half of the grey matter is divided into a
• Dorsal horn – Cell bodies of inter neurons.
• Ventral horn – Efferent motor neurons supplying the skeletal muscle.
• Lateral horn – Nerves supply to heart smooth muscles exocrine glands. Originate from the cell bodies.
• Ascending tract – This carry sensory impulses to the brain.
• Descending tract – This carry motor impulses to brain.

Question 16.
Give an account of the functional components of a reflex arc.
Answer:
Sensory receptor – It is a sensory structure that responds to specific stimulus.
Sensory neuron – This neuron takes the sensory impulse to the grey (afferent) matter of the
spinal cord through the dorsal root of the spinal cord.
Inter neuron – It may serve to transmit the impulses from the sensory neuron to the motor neuron.
Motor neuron – It transmits impulse from CNS to the effector organ
Effector neuron – It may be a muscle or gland which responds to the impulse received.

• Lacrymal glands located in the upper lateral region of each orbit secrete tears.
• Tears are secreted at the rate of 1 ml/day.
• Tears contain salt mucus and lysozyme enzyme to destroy bacteria.
• The protective mucus membrane present in the outer surface of the eye ball.
• The eye has two compartments anterior and posterior compartments filled with aqueous humour and vitreous humour respectively.
• The eye ball is consists of three layers sclera, vascular choroid and sensory retina.

Sclera:

• It consists of anterior cornea and the posterior sclera.
• Cornea is composed of stratified squamous epithelium. Sclera forms the white of the eye and protects the eyeball.
• At the junction of the sclera and the cornea is a channel called canal of schlemm which continuously drains out the excess of aqueous humour.

Choroid layer:
It is highly vascularised pigmented layer.

Question 17.
Tabulate the differences between sympathetic and parasympathetic neural system.
Answer:

Sympathetic Neural System (SNS)	Parasympathetic Neural System (PNS)
SNS originates in the thoracic and lumbar region of the spinal cord.	PNS originates in the cranial region of the brain and the sacral region of the spinal cord.
Sympathetic ganglia are linked up to form a chain.	Its ganglia remain isolated
Preganglionic fibres are short and the postganglionic fibres are long.	Preganglionic fibres are long and the postganglionic fibres are short.
Noradrenaline is produced at the terminal ends of the postganglionic fibres at the effector organs. Hence the system is adrenergic.	Acetylcholine is produced at the terminal ends of the postganglionic fibres at the effector organs. Hence the system is cholinergic.
Active during stressful conditions preparing the body to face them.	Active during relaxing times restoring normal activity after a stress.
The overall effect is excitatory and stimulating.	The overall effect is inhibitory.
It is considered as the flight or fight system.	It is considered as “The rest and Digest System” or “The Feed and Breed System”.

Question 18.
Give an account of the peripheral nervous system.
Answer:

• All nervous tissue outside the central nervous system is the peripheral neural system.
• It includes nerves ganglia enteric plexuses and sensory receptors.
• Ganglia are Sinai masses of nervous tissue.
• The neurons of these plexuses help in regulating the digestive system.
• The specialised structure that helps to respond to changes in the environment are called sensory receptor.
• This triggers nerve impulses along the afferent fibres to CNS.
• PNS comprises 12 pairs of cranial nerves and 31 pairs of the spinal nerve.
• The neural retina layer consists of cones and rods.
• The yellow flat spot at the centre of the posterior region of the retina is called macula lutea.
• A small depression present in the centre of the

Question 19.
Explain the Autonomic Neural System?
Answer:
The autonomic neural system is auto-functioning and self-governed. It is a part of the peripheral neural system that innervates smooth muscles, glands, and cardiac muscle. This system controls and coordinates the involuntary activities of various organs. ANS controlling centre is in the hypothalamus.

An autonomic neural system comprises the following components:

1. A preganglionic neuron whose cell body is in the brain or spinal cord; its myelinated axon exits the CNS as part of cranial or spinal nerve and ends in an autonomic ganglion.
2. Autonomic ganglion consists of an axon of preganglionic neurons and cell bodies of the postganglionic neurons.
3. Postganglionic neuron conveys nerve impulses from autonomic ganglia to visceral effector organs.
4. The autonomic neural system consists of the Sympathetic neural system and the Parasympathetic neural system.

Question 20.
Draw the diagram of the cross-section of the eye.
Answer:

Question 21.
Describe the mechanism of vision.
Answer:

• When light enters the eye it gets refracted by the cornea, aqueous humor and lens and it is focused on the retina and excites the rod and cone cells.
• The rods and cones contain the retinal a derivative of vitamin A and the photo pigment opsin.
• Light induces dissociation of retinal from opsin and causes the structural changes in opsin.
• This generates an action potential in the photo receptor cells.
• It is transmitted by the optic nerves to the visual cortex of the brain via the optic nerves for the perception of vision.

Question 22.
List the refractive errors of eye.
Answer:
Myopia

• The affected person cannot see distant objects.
• As the eyeball is elongated or thickened lens the image of distant object is formed in front of the yellow spot.
• This error can be corrected using a concave lens.

Hypermetropia

• Affected person cannot see the nearby objects.
• This is due to a shortened eyeball and thin lens. So the image of closest object is converged behind the retina.
• This defect can be corrected by using convex lens.

Presbyopia

• Due to aging, the lens loses elasticity and the power of accommodation.
• Convex lenses are used to correct this defect.

Astigmatism

• It is due to the rough curvature of the cornea or lens.
• Cylindrical glasses are used to correct this error.

Question 23.
Describe the structure of an ear?
Answer:
Anatomically the ear is divided into three regions external ear middle ear and inner ear.
External ear:

• It consists of pinna external auditory meatus and ear drum.
• The pinna collects the sound waves.
• The external auditory meatus extends up to the tympanic membrane.
• The tympanic membrane is covered with skin outside and with mucus membrane inside.

Middle ear:

• It is an air-filled cavity in the temporal bone.
• The middle ear contains three ossicles malleus incus and stapes.
• The malleus is attached to the tympanic membrane and its head articulates with the incus.
• The stapes is attached to the oval window in the inner ear.
• The Eustachian tube connects the middle ear cavity with the pharynx

Inner ear:-

• It is the fluid-filled cavity consisting of two parts the bony labyrinth and the membranous labyrinths.
• The bony labyrinth consists of three areas, cochlea, vestibule, and semicircular canals.

a Cochlea is a coiled portion consists of 3 chambers namely.

1. Scala vestibule
2. Scala media
3. Scala tympanii.

Scala vestibule and scala tympani are filled with peri lymph.
The scala media is filled with endo lymph.

Question 24.
Describe the structure and functions of organ of cortii.
Answer:

• Organ of corti is a sensory ridge located on the top of the basilar membrane.
• Basilar membrane contains numerous hair cells that are arranged in four rows.
• Protruding from the apical part of each hair cell is hair like structures known as stereocilia.
• On the organ of cortii a stiff gel membrane called tectorial membrane is situated.
• During the conduction of sound wave sterocilia makes contact with tectorial membrane.

Question 25.
Explain the Refractive errors of the eye or defects of the human eye?
Answer:
Myopia (nearsightedness): The affected person can see the nearby objects but not the distant objects. This condition may result due to an elongated eyeball or thickened lens; so that the image of a distant object is formed in front of the yellow spot. This error can be corrected using a concave lens that diverges the entering light rays and focuses them on the retina.

Hypermetropia (long-sightedness): the affected person can see only the distant objects clearly but not the objects nearby. This condition results due to a shortened eyeball and thin lens; so the image of the closest object is converged behind the retina. This defect can be overcome by using a convex lens that converges the entering light rays on the retina.

Presbyopia:
Due to aging, the lens loses elasticity and the power of accommodation. Convex lenses are used to correct this defect. Astigmatism is due to the rough (irregular) curvature of the cornea or lens. Cylindrical glasses are used to correct this error.

Cataract:
Due to the changes in the nature of the protein, the lens becomes opaque. It can be corrected by surgical procedures.

Question 26.
Differentiate the rods from cones.
Answer:

Rods	Cones
1. Helps in seeing in dim light	Colour perception in bright light
2. Contains Rhodopsin pigment	Contains photopsin
3. The protein retinol and vitamins aldehyde combine to form scotoptin called Rhodopsin	The protein opsin and retinol combine to form photopsin.
4. There are 120 million rods are seen on the retina	6-7 million cone cells are seen on the retina
5. Rods are seen richly over the surface of the foveal region.	Cones are richly present on the foveal region.

Question 27.
A man is cheating with his family in this time a house fly sits on his back at once he lifts the hand and strikes the fly. How can he know that? What are the structures involved in this perception?
Answer:

• The skin senses this skin is the largest sense organ.
• All over the skin sensory receptors of pressure heat cold and pain.
• Following are the sensory receptors of the skin.

Tactile Merkel disc

• It is a light touch receptor lying in the deeper layer of the epidermis.
• Hair follicle receptors. These are light-touch receptors lying around the hair follicles.

Meissner’s corpuscles

• These are small light pressure receptors found just beneath the epidermis in the dermal papillae.
• They are numerous in hair less skin areas such as finger tips and soles of the feet.

Pacinian corpuscles

• These are the large egg-shaped receptors found scattered in the dermis.
• It detects different textures temperature hardness and pain.

Ruffini endings
This lie in the dermis responds to continuous pressure Krause end bulbs are thermo receptors that sense temperature.

Question 28.
Give notes on Defects of the ear.
Answer:

• Deafness may be temporary or permanent
• Conductive deafness
• Possible causes
• The blockage of the ear canal with ear wax.
• Rupture of the ear drum.
• Middle ear infection with fluid accumulation,
• Restriction of ossicular movement.
• Sensory-neural deafness
• The defect may be in the organ of cortii or the auditory nerve or in the ascending auditory pathways or auditory cortex.

Question 29.
Give an account of the mechanism of sound?
Answer:

• Sound waves entering the external auditory meatus fall on the tympanic membrane and get vibrated.
• These vibrations are transmitted to the oval window through the three ear ossicles.
• Since the tympani membrane is 17-20 times larger than the oval windows. This pressure exerted on the oval window is about 20 times more than that on the tympanic membrane.
• This pressure causes the round window to alternately bulge outward and inward meanwhile the basilar membrane along with the organ of Corti moves up and down.
• These movements of hair alternately open and close the mechanically gated ion channel causes action potential.
• This is propagated to the brain as a sound sensation through the cochlear nerve.

Question 30.
Explain the sensory function of skin?
Answer:
Skin is the sensory organ of touch and is also the largest sense organ. This sensation conies from millions of microscopic sensory receptors located all over the skin and associated with the general sensations of contact, pressure, heat, cold and pain. Some parts of the body, such as the fingertips have a large number of these receptors, making them more sensitive. Some of the sensory receptors present in the skin are:

• Tactile Merkel disc is a light touch receptor lying in the deeper layer of the epidermis.
• Hair follicle receptors are light-touch receptors lying around the hair follicles.
• Meissner’s corpuscles are small light pressure receptors found just beneath the epidermis in the dermal papillae. They are numerous in hairless skin areas such as fingertips and soles of the feet.
• Pacinian corpuscles are the large egg-shaped receptors found scattered deep in the dermis and monitoring vibration due to pressure. It allows detecting different textures, temperatures, hardness, and pain.
• Ruffini endings which lie in the dermis respond to continuous pressure.
• Krause end bulbs are thermoreceptors that sense temperature.

Question 31.
Describe the structure of the receptor involved with a diagram.
Answer:

• Taste buds are flask-shaped. There are two major types.
• Gustatory epithelial cells or taste cells.
• Basal epithelial cells or repairing cells.
• Long micro villi called gustatory hairs project from the tip of the gustatory cells and extends through a taste pore to the surface of the epithelium.
• Gustatory hairs are tire sensitive portion of the gustatory cells and they have sensory dendrites which send the signal to the brain.
• The basal cells that act as stem cells divide and differentiate into new gustatory cells.