A nerve cell has an axon that extends 3 cm with an internode

A nerve cell has an axon that extends 3 cm with an inter-node spacing of 2 mm. Calculate the membrane potential at a node just prior to the generation of an action potential given the following information: Membrane length constant = 1 mm Threshold = -35 mV Resting membrane potential (RMP) = -60 mV Action potential overshoot +20 mV. What is the membrane potential at the next node, and is depolarization sufficient to generate another action potential? % Response = 100(1 - e^41) -49 mV. and an AP will NOT occur at node 2 -30 mV. and an AP WILL occur at node 2 -69 mV. and an AP WILL occur at node 2 -25 mV, and an AP will NOT occur at node 2 Explain how the length constant is affected following degradation of the myelin sheath, or in other words, how is the length constant affected by decreases in membrane resistance (Rm)? How does demyelination affect conduction along the axon? Name one disease that causes demyelination.

Solution

2. The myelin sheath increases the length constant and decreasing capacitance. The length constant is the distant that an ions travel before it leaks out of the cell. It is determined by finding the square of the membrane resistence ( Rm) than internal resistence ( Ri). lets remove the and directly focus on the relationship of Rm and Ri. While you are focusing on the myelin, lets keep the internal resistance constant. Rm is the nuemarator and Ri is the denominator. Let us fix the denominator at one. noe compare the numerator when it is 2 versus i.e, 10. 2/1 is smaller than 10/1

3 Myelin is an material that is worn away or damaged decreases the nerve function. this type of damaged nerves are known as demyelination. demyelinated sheath are the protective covering that surrounds the spinal cord and nerve fibre. when the myeline sheath damage the nerver impulses stop and causes the neurological problems.

There are two different types of demyelination. they are the (i) inflammatory demyelination and (ii) viral demyelination.

The most common causes diseases of demyelination is the MS. Multiple Sclerosis (ms) is the most common disease in brain and the central nervous system. The demyelinating disease occurs in the white matter of the brain and the spinal cord.

In this disease the immune system that attacks the myelin sheath or the cells that produce and maintain it. This causes inflammation and injury to the sheath and causes multiple areas of scaring. Inflammation is most common causes for the MS. There are certain viral infections, metabolic problems and loss of oxygen can cause for this infections.

MS diseases and some other demyelinating diseases results in the loss of sensation, loss of vision, mussule weakness, muscle stiffness, pains and etc.,