Question

Put these events in the correct chronological sequence:

1. End-plate potentials trigger action potentials.
2. Transverse tubules convey potentials into the interior of the cell.
3. Acetylcholine binds to receptors on the motor end plate.
4. Ca₂₊ is released from the sarcoplasmic reticulum.
A) 1, 2, 3, 4
B) 3, 1, 2, 4
C) 2, 1, 4, 3
D) 3, 1, 4, 2
E) 4, 3, 2, 1

Answer 1

The correct chronological sequence of events after a motor neuron stimulates a muscle fiber is Acetylcholine binds to receptors, end-plate potentials trigger action potentials, transverse tubules convey the potentials into the cell interior, and Ca2+ is released, making the order 3, 1, 2, 4.

Step-by-step explanation:

The correct chronological sequence of events for a muscle contraction after a motor neuron is stimulated is as follows:

1. Acetylcholine binds to receptors on the motor end plate.
2. End-plate potentials trigger action potentials.
3. Transverse tubules convey potentials into the interior of the cell.
4. Ca2+ is released from the sarcoplasmic reticulum.

Therefore, the correct order is 3, 1, 2, 4, which corresponds to option B. This sequence ensures that the neurotransmitter signal leads to muscle contraction through excitation-contraction coupling. Each step is crucial and the process is fast and precise to enable proper muscle function.

The correct chronological sequence of these events is B) 3, 1, 2, 4. First, acetylcholine binds to receptors on the motor end plate, creating an end-plate potential. Next, the end-plate potential triggers an action potential that travels down the T tubules, which are invaginations in the sarcolemma. Then, Ca2+ is released from the sarcoplasmic reticulum in response to the change in voltage. Finally, the released Ca2+ initiates muscle contraction by interacting with the actin and myosin filaments