33. Multiple sclerosis is an autoimmune disease that attacks ___________________

Question

33. Multiple sclerosis is an autoimmune disease that attacks ___________________________ in the ___________________ to cause the loss of ____________________ along the ______________________ regions of neurons. The effect of this disease is to block action potential _______________________ by increasing membrane _______________________ in regions of the neuron that had previously been the ____________________________ regions.

34. The release of the neurotransmitter glutamate at synapses in the central nervous system opens __________ gated channels that permit the influx of ______ into the postsynaptic cell to produce depolarizations known as ________________________. These potentials ________________ at the ___________________________ to generate ____________________ if the amplitude of the depolarization exceeds ___________________ and _____________ exceeds ________________.

35. The neurotransmitters GABA (gamma amino butyric acid) and glycine bind to receptors that open to ____________________ membrane permeability to ___________________. If the equilibrium potential for chloride (ECl) is greater than the resting membrane potential, the potential will be ____________________. The effect of this increased permeability will be to________________ the membrane resistance (Rm) leading to a _________________ in the ________________________ and ____________________ of __________________________ described in question 34.

Explanation / Answer

33) Multiple sclerosis is an autoimmune disease that attacks the nerve fibers in the brain and spinal cord to cause the loss of myelin sheath protein along the axonal regions of neurons. The effect of this disease is to block action potential of voltage gated sodium channels by increasing membrane depolarization in regions of the neuron that had previously been the internodal regions.

Multiple sclerosis is an autoimmune disease affecting the brain and spinal cord. It induces demyelination of the nerve cells, resulting in loss of nerve conduction. Myelin is a fatty protein that surrounds the axons of the neurons. Neurons will have at least one axon. Myelin is synthesized by Schwann cells and coats the axon.

Demyelination is the loss of myelin at the internodal region. It results in blockage of action potential of the sodium ion channels. Depolarization of the membrane will cause influx of sodium ions into the cells, increasing the membrane potential initially. Sodium channels will be eventually blocked. It takes longer to reach the threshold in the next node. Hence, conduction of impulse is stopped at the internodal region.

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