Question 53

The myelin sheath deteriorates in an individual with multiple sclerosis.

In multiple sclerosis, the myelin sheath, which insulates nerve fibers in the central nervous system, is damaged. This deterioration disrupts the normal transmission of electrical impulses, resulting in muscle weakness and uncoordinated movements.

A) Myelin sheath

This option is correct because multiple sclerosis specifically targets the myelin sheath, leading to its degeneration. The loss of this protective layer around nerve fibers impairs nerve signal conduction, causing the symptoms associated with the disease.

B) Synaptic vesicles

Synaptic vesicles are responsible for storing neurotransmitters at the synapse and are not directly affected in multiple sclerosis. While they play a role in neurotransmission, their deterioration does not lead to the characteristic symptoms of muscle weakness and uncoordinated movements seen in this condition.

C) Axon terminals

Axon terminals are the endings of neurons where neurotransmitters are released. Although they are integral to neuronal communication, their deterioration is not the primary factor in multiple sclerosis. The disease primarily affects the myelin sheath rather than the axon terminals themselves.

D) Dendrites

Dendrites are the branches of neurons that receive signals from other neurons. While they are important for signal reception, they do not undergo the deterioration seen in multiple sclerosis. The condition primarily impacts the myelin sheath, not the structure or function of dendrites.

Conclusion

The myelin sheath's deterioration is central to the pathology of multiple sclerosis, leading to impaired nerve function and the resultant symptoms. Other options, such as synaptic vesicles, axon terminals, and dendrites, do not directly relate to the degenerative processes of this disease, thereby reinforcing why the myelin sheath is the correct answer.