(a) Afferent neurons and efferent neurons
|
Afferent neurons |
Efferent neurons |
|
Afferent neuron conducts nerve impulses toward the brain or the spinal cord. |
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 an unmyelinated nerve fibre
|
Impulse conduction in a myelinated nerve fibre |
|
Impulse conduction in an unmyelinated nerve fibre |
|
1. |
In a myelinated nerve fibre, the action potential is conducted from one node to another. |
1. |
In an 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. |
The conduction of impulses is faster. |
2. |
The conduction of impulses is slower. |
(c) Aqueous humour and vitreous humour
|
Aqueous humour |
Vitreous humour |
|
It is a thin, watery fluid present between the cornea and the lens. |
It is a transparent gel present between the lens and the retina. |
(d) Blind spot and yellow spot
|
Blind spot |
|
Yellow spot |
|
1. |
Blind spot is a spot on the retina present at the point of origin of the optic nerve. |
1. |
Yellow spot is a small area on the retina present at the posterior pole of the eye, lateral to the blind spot. |
|
2. |
Photoreceptor cells are absent from this region. |
2. |
Only cones are present in this region. |
|
3. |
They are insensitive to light as both rods and cones are absent. |
3. |
They are sensitive to bright light as cones are present. |
(f) Cranial nerves and spinal nerves
|
Cranial nerves |
|
Spinal nerves |
|
1. |
Cranial nerves arise from the brain. |
1. |
Spinal nerves arise from the spinal cord. |
|
2. |
There are 12 pairs of cranial nerves. |
2. |
There are 31 pairs of spinal nerves. |
