Distinguish between: (a) afferent neurons and efferent neurons (b) impulse conduction in a myelinated nerve fibre and unmyelinated nerve fibre (c) aqueous humor and vitreous humor (d) blind spot and yellow spot (f) cranial nerves and spinal nerves.

(a) Afferent neurons and Efferent neurons
Afferent Neurons:- Afferent neuron conducts nerve impulses toward the brain or the spinal cord.
Efferent Neurons:- Efferent neuron conducts nerve impulses from the brain or spinal cord to the effector organs such as muscles or glands.

(b) Impulse conduction in a myelinated nerve fibre and unmyelinated nerve fibre
Impulse Conduction in a Myelinated Nerve Fibre:-
1. Myelinated nerve fibre, the action potential is conducted from one node to another.
2. Conduction of impulses is faster.
Impulse Conduction in an Unmyelinated Nerve Fibre:-
1. Unmyelinated nerve fibre, the action potential is not conducted from node to node. It is carried along the whole length of the nerve fibre.
2. Conduction of impulses is slower.

(c) Aqueous humor and vitreous humor:-
Aqueous Humour:- Thin, watery fluid present between the cornea and the lens.
Vitreous Humour:- Transparent gel present between the lens and the retina.

(c) Blind spot and yellow spot:-
Blind Spot:-
1. Blind spot is a spot on the retina present at the point of origin of the optic nerve.
2. Photoreceptor cells are absent from this region.
3. Insensitive to light as both rods and cones are absent.
Yellow Spot:-
1. Yellow spot is a small area on the retina present at the posterior pole of the eye, lateral to the blind spot.
2. Only cones are present in this region.
3. Sensitive to bright light as cones are present.

(f) Cranial nerves and spinal nerves.
Cranial Nerves:-
1. Cranial nerves arise from the brain.
2. 12 pairs of cranial nerves.
Spinal Nerves:-
1. Spinal nerves arise from the spinal cord.
2. 31 pairs of spinal nerves

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