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In the disease multiple sclerosis, the myelin sheath surrounding the axons of neurons is broken down - VCE - SSCE Biology - Question 10 - 2014 - Paper 1
Question 10
In the disease multiple sclerosis, the myelin sheath surrounding the axons of neurons is broken down. One of the symptoms of multiple sclerosis is weakening of the m... show full transcript
Worked Solution & Example Answer:In the disease multiple sclerosis, the myelin sheath surrounding the axons of neurons is broken down - VCE - SSCE Biology - Question 10 - 2014 - Paper 1
Step 1
A. the transmission of electrical impulses along the axons of neurons is slowed.
Answer
In multiple sclerosis, the loss of the myelin sheath impairs the conduction of electrical impulses. The myelin sheath serves as an insulator, allowing for fast and efficient transmission of signals along the axons. When this sheath is damaged, as seen in multiple sclerosis, the electrical signals are delayed, leading to weakened muscle responses.
Step 2
B. the size of the electrical impulses travelling along the axons is smaller.
Answer
Although the size of electrical impulses can influence signal transmission, it is not the primary effect seen in multiple sclerosis. The main issue arises from the slowed transmission due to the loss of myelin, rather than the size of the impulses themselves.
Step 3
C. neurotransmitter receptors on the muscle cells have become less sensitive.
Answer
While less sensitivity of neurotransmitter receptors can contribute to muscle weakness, the primary issue in multiple sclerosis is the impaired transmission of signals due to myelin damage. This leads to a more significant impact on muscle strength than receptor sensitivity.
Step 4
D. neurotransmitters are inhibited from travelling along the neurons.
Answer
This statement suggests a blockage in neurotransmitter movement, which is not the main concern in multiple sclerosis. The disease primarily affects the transmission of impulses due to myelin degeneration, rather than the neurotransmitters being inhibited in their travel.