Explain the following processes: (a) Polarisation of the membrane of a nerve fibre (b) Depolarisation of the membrane of a nerve fibre (c) Conduction of a nerve impulse along a nerve fibre (d) Transmission of a nerve impulse across a chemical synapse
(a) Polarisation of the membrane of a nerve fibre During resting condition, the awareness of K ions is greater in the axoplasm whilst the awareness of Na ions is extra out of doors the axoplasm. As a result, the potassium ions flow quicker from interior to out of doors in comparison to sodium ions. Therefore, the membrane turns into definitely charged out of doors and negatively charged interior. This is called polarization of membrane or polarized nerve.(b) Depolarisation of the membrane of a nerve fibre When an electrical stimulus is given to a nerve fibre, an motion ability is generated. The membrane will become permeable to sodium ions than to potassium ions. This outcomes into nice rate inner and bad rate outdoor the nerve fibre. Hence, the membrane is stated to be depolarized.(c) Conduction of a nerve impulse alongside a nerve fibre There are sorts of nerve fibres - myelinated and non-myelinated. In myelinated nerve fibre, the motion ability is performed from node to node in leaping manner. This is due to the fact the myelinated nerve fibre is lined with myelin sheath. The myelin sheath is impermeable to ions. As a result, the ionic trade and depolarisation of nerve fibre isnot feasible alongside the complete period of nerve fibre. It takes area handiest at a few point, referred to as nodes of Ranvier, while in non-myelinated nerve fibre, the ionic alternate and depolarization of nerve fibre takes location alongside the complete duration of the nerve fibre. Because of this ionic alternate, the depolarized region will become repolarised and the subsequent polarized place will become depolarized. (d) Transmission of a nerve impulse throughout a chemical synapse Synapse is a small hole that takes place among the final part of the axon of 1 neuron and the dendrite of subsequent neuron. When an impulse reaches on the give up plate of axon, vesicles along with chemical substance or neurotransmitter, which include acetylcholine, fuse with the plasma membrane. This chemical movements throughout the cleft and attaches to chemo-receptors gift at the membrane of the dendrite of subsequent neuron. This binding of chemical with chemo-receptors results in the depolarization of membrane and generates a nerve impulse throughout nerve fibre. The chemical, acetylcholine, is inactivated through enzyme acetylcholinestrase. The enzyme is gift withinside the post synaptic membrane of the dendrite. It hydrolyses acetylcholine and this lets in the membrane to repolarise.
