Question

When experimentally applying curare to a muscle, you find that it does not contract when the motor neuron leading to it is electrically stimulated. If you knew that this toxin blocks acetylcholine receptors, what can you conclude about the failure to contract?a.A contraction fails to occur because this toxin directly prevents calcium ion release from intracellular stores.b.A contraction fails to occur because an action potential is not generated in the muscle cell.c.A contraction fails to occur because neurotransmitter release by the motor neuron is blocked at the neuromuscular junction.d.A contraction fails to occur because acetylcholine is not released from the motor neuron.e.A contraction fails to occur because this toxin prevents cross-bridge formation and thereby directly prevents contraction.

Answer 1

Answer:

C) Contraction fails to occur because neurotransmitter release by the motor neuron is blocked at the neuromuscular junction.

Explanation:

• Acetylcholine is a neurotransmitter found in synapse between the neurons.
• Acetylcholine is released from one cell and it transmits the signal by binding to the receptors on the other cell.
• Neuromuscular junction is a chemical synapse. So, if in a neuromuscular junction a toxin block the acetylcholine receptor the signal will not be transmitted and the muscle will not contract or relax.