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Practice each question, then open the answer or worked solution.
The region of the vertebrate eye, where the optic nerve passes out of the retina, is called the (a) fovea
(b) iris
(c) blind spot
(d) optic charisma
Ans : (c) blind spot
Distinguish between
a) Afferent neurons and Efferent neurons
Ans:
Afferent Neurons | Efferent Nerve Cells |
They transmit impulses toward the central nervous system. | Impulses are conducted away from the central nervous system by these fibres. |
It stimulates the senses and evokes them. | It causes the effectors to respond. |
Their nature is sensory. | In nature, they have motor functions. |
Information is taken from the receptors. | The effectors receive the information.. |
b) Impulse conduction in a myelinated nerve fibre and an unmyelinated nerve fibre
Ans:
Impulse Conduction in Myelinated Nerve Fibre | Impulse Conduction in an Unmyelinated Nerve Fibre |
If a node of Ranvier lacks a myelin coating, depolarization occurs. | The nerve fibres are depolarized along their entire length. |
There is a jump between different nodes of Ranvier regarding action potential. | Fibres carry action potential along their entire length. |
The pace of conduct is faster. | The pace of conduct is slower. |
It requires less energy. | Energy is required in greater amounts. |
c) Aqueous humour and Vitreous humour
Ans:
Aqueous Humour | Vitreous Fluid |
It is transparent and watery in nature. | A transparent, thick gel-like fluid is present. |
Lenses and corneas are in contact with it. | The lens and retina are connected by this structure. |
Ciliary glands continuously secrete it, which drains from the eyes. | There is no replacement for it. |
Lenses, corneas, and other parts of the anterior chamber receive nourishment from it. | There is no nutritional value to it. |
d) Blindspot and Yellow spot
Ans:
Blindspot | Yellow Spot |
Blind spots are prominent at the origin of the optic nerve - an area of the retina containing a solitary yellow spot. | A yellow spot is a small area of the retina located lateral to the blind spot, at the posterior pole of the eye. |
There is no shallow depression. | The fovea centralis is a shallow depression. |
In this region, no photoreceptors are present. | In this region, only cones exist. |
Light has no effect on it. | Bright light affects its sensitivity. |
A photoreceptor cell is not present in this region. | In this region, there are only cones. |
A blind spot does not form an image. | At the yellow spot, an image is formed. |
e) Cranial nerves and Spinal nerves
Ans:
Cranial Nerves | Spinal Nerves |
These originate from the brain. | They are nerves that originate in the head and originate in the spinal cord. |
The brain is composed of 12 pairs of cranial nerves. | 31 spinal nerves make up the spine. |
The brain and body are connected by them.
| Parts of the spinal cord are connected to them. |
Depending on their nature, they could be sensory, motor, or mixed. | In nature, they are mixed. |