Give a brief account of:

(a) Mechanism of synaptic transmission

(b) Mechanism of vision

(c) Mechanism of hearing

Asked by Pragya Singh | 11 months ago |  46

1 Answer

Solution :-

(a) A synapse is a point where two neurons meet. It exists between one neuron's axon terminal and the dendrite of the next neuron, divided by a cleft. Synaptic transmission occurs in two ways.

(1) Chemical Transmission- A neurotransmitter (acetylcholine) is released across the synaptic cleft when a nerve impulse reaches the end plate of an axon. This substance is produced in the neuron's cell body and delivered to the axon terminal. Acetylcholine diffuses over the cleft and attaches to receptors on the surface of the next neuron's membrane. This results in membrane depolarization and the initiation of an action potential.

(2) Electrical transmission- An electric current is created in the neuron in this sort of transmission. This electric current causes an action potential, which results in nerve impulse transmission across the nerve fibre. This technique of nerve conduction is quicker than the chemical method of transmission.

(b) The retina is the eye's innermost layer. Inner ganglion cells, middle bipolar cells, and outermost photoreceptor cells make up the three layers. A photoreceptor cell is made up of a protein called opsin and a vitamin A aldehyde known as retinal. The separation of the retinal from opsin protein occurs when light rays are focused on the retina through the cornea. Opsin's structure is altered as a result of this. The permeability of the membrane changes as the structure of opsin changes, resulting in a potential differential in the cells. This causes an action potential in the ganglionic cells, which is then communicated to the brain's visual cortex via optic nerves. The impulses are analysed in the cortex portion of the brain, and an image is generated on the retina.

(c) Sound waves are collected by the pinna of the external area and sent to the eardrum or external auditory canal. Vibrations are formed when these waves hit the tympanic membrane. The vibrations are then conveyed to the oval window, fenestra ovalis, via the malleus, incus, and stapes, three ear ossicles. These ossicles in the  ear operate as a lever, transmitting sound waves to the inner ear.The vibrations of the fenestra ovalis are conveyed to the cochlea. The lymph produces sound waves as a result of this. A ripple in the basilar membrane is caused by the creation of waves. The sensory hair cells on the organ of corti bend against the tectorial membrane as a result of this action. Sound waves are turned into nerve impulses as a consequence of this. Auditory nerves then carry these signals to the auditory cortex of the brain. The impulses are analysed and sound is identified in the cerebral cortex of the brain

Answered by Abhisek | 11 months ago

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