Question

Put the following structures in order in terms of how they are used during muscle contraction.

a) T-tubules, synaptic bulb (synaptic knob), synaptic vesicle, motor neuron axon, synaptic cleft, motor end plate, sarcoplasmic reticulum, Sarcomere
b) Sarcomere, motor end plate, synaptic bulb (synaptic knob), synaptic vesicle, motor neuron axon, synaptic cleft, sarcoplasmic reticulum, T-tubules
c) Motor neuron axon, T-tubules, Sarcomere, sarcoplasmic reticulum, synaptic bulb (synaptic knob), synaptic vesicle, motor end plate, synaptic cleft
d) Motor end plate, Sarcomere, sarcoplasmic reticulum, T-tubules, synaptic cleft, synaptic bulb (synaptic knob), synaptic vesicle, motor neuron axon

Answer 1

The structures are used in the order of motor neuron axon, synaptic bulb (synaptic knob), synaptic vesicle, synaptic cleft, motor end plate, T-tubules, sarcoplasmic reticulum, and Sarcomere during muscle contraction, reflecting the process of excitation-contraction coupling.

Step-by-step explanation:

The correct order in which structures are used during muscle contraction is: motor neuron axon, synaptic bulb (synaptic knob), synaptic vesicle, synaptic cleft, motor end plate, T-tubules, sarcoplasmic reticulum, and Sarcomere. This sequence represents the path of neural signal transmission from the motor neuron to the muscle fiber that results in contraction.

1. Motor neuron axon: Conducts electrical signals to the muscle fiber.
2. Synaptic bulb (synaptic knob): Located at the end of the motor neuron axon and contains synaptic vesicles with neurotransmitters.
3. Synaptic vesicle: Stores the neurotransmitter acetylcholine within the synaptic bulb.
4. Synaptic cleft: A gap between the synaptic bulb and the motor end plate where the neurotransmitter diffuses.
5. Motor end plate: The area of the sarcolemma on the muscle fiber that has receptors for acetylcholine.
6. T-tubules: Transmit the action potential deeper into the muscle fiber.
7. Sarcoplasmic reticulum: Stores calcium ions and releases them in response to the action potential to begin muscle contraction.
8. Sarcomere: The contractile unit of the muscle where the sliding filament mechanism occurs.

This sequence underpins the process of excitation-contraction coupling, which is how a neural signal translates into a muscle contraction.