The Effect of Myelination

Question: Explain the effect of Myelination on the rate of nerve Impulse Conduction? Answer: Conduction of nerve impulse: Nerve impulse is carried through neuron which is regarded as s cell in human nervous system. Respond to any stimulus is done through nerve impulse through neurons. Stimuli may be any kind of touch, sound, light etc and in this way communicate with each other. Calcium and sodium ions are responsible for conduction of nerve impulse. Sodium ions are responsible for membrane potential across the nerve membrane. Membrane potential helps in transfer of signal through active sodium potassium pump. Sodium ions move outside from inside the nerve and potassium ions move inside from outside creating an action potential which carries the nerve impulse. Calcium ions are released from voltage gated channels of calcium at the synapse of one neuron to another and trigger the release of neurotransmitter molecules (2). Neurotransmitter molecules are responsible for activation of post synaptic neuron which causes transfer of responses from one neuron to another. E.g. of a neurotransmitter is acetylcholine. Receptors are the membrane units which are required to identify the receptive molecules. For e.g. acetylcholine receptor at post synaptic neuron which receives signal after receipting acetylcholine molecules. Enzymes are responsible for conduction of nerv e response as they help in movement of sodium and potassium ions across membrane, helps in release of calcium ions and neurotransmitter. Effect of myelination on rate of nerve impulse: Myelin sheath is present surrounding the axon of neuron and is secreted by glial cells. It helps in fast conduction of nerve impulse as myelin is made up of fat and fat acts as insulator so do not conduct impulse. Sodium channels which are present at high concentration at nodes help in faster conduction as impulse will jump from node to node and transfer signal faster (1). References Gutkin, B. and G. B. Ermentrout. 2006. Neuroscience: spikes too kinky in the cortex? Nature 440: 999-1000. Schikorski, T. and C. F. Stevens. 2010. Morphological correlates of functionally defined synaptic vesicle populations. Nature Neuroscience 4: 391-395.