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.
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Answer
This option correctly identifies a main issue associated with multiple sclerosis. The myelin sheath facilitates the rapid transmission of electrical impulses. When this sheath is damaged, the conduction velocity decreases, leading to slower impulse travel, which contributes to muscle weakness.
Step 2
B. the size of the electrical impulses travelling along the axons is smaller.
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This option is misleading. The size of the electrical impulses does not typically decrease, rather the ability to transmit these impulses effectively is impaired due to the damaged myelin sheath.
Step 3
C. neurotransmitter receptors on the muscle cells have become less sensitive.
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While decreased sensitivity of neurotransmitter receptors can contribute to muscle weakening, it is not the primary cause linked directly to the breakdown of the myelin sheath in multiple sclerosis.
Step 4
D. neurotransmitters are inhibited from travelling along the neurons.
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This option incorrectly attributes muscle weakness to neurotransmitters being inhibited from travelling. The primary issue is the inability to conduct impulses effectively due to myelin damage, not a blockage of neurotransmitter movement.
