Question

drag the text blocks below into their correct order. an action potential is initiated and propagates to the motor neuron axon terminal. acetylcholine diffuses from the axon terminal to the motor end plate of the skeletal muscle fiber. following depolarization of the neurilemma in the axon terminal, ca²⁺ enters through voltage - gated ca²⁺ channels. more na⁺ moves into the fiber at the motor end plate than k⁺ moves out, depolarizing the membrane and producing the end - plate potential (epp). this triggers the release of acetylcholine from the axon terminal. acetylcholine binds to nicotinic receptors on the motor end plate membrane, increasing their permeability to na⁺ and k⁺. the conclusion of excitation at the neuromuscular junction involves acetylcholine degradation by acetylcholinesterase. local currents depolarize the adjacent muscle cell plasma membrane to its threshold potential. a/an action potential is generated, which propagates along the skeletal muscle fiber surface and into the fiber along the t - tubules.

Explanation:

The neuromuscular - junction process starts with an action potential in the motor neuron axon terminal. Depolarization allows calcium entry, triggering acetylcholine release. Acetylcholine then diffuses and binds to receptors, leading to ion movements and end - plate potential. Local currents depolarize the muscle membrane further, generating an action potential in the muscle fiber. Finally, acetylcholine is degraded.

Answer:

1. An action potential is initiated and propagates to the motor neuron axon terminal.
2. Following depolarization of the neurilemma in the axon terminal, Ca²⁺ enters through voltage - gated Ca²⁺ channels.
3. This triggers the release of acetylcholine from the axon terminal.
4. Acetylcholine diffuses from the axon terminal to the motor end plate of the skeletal muscle fiber.
5. Acetylcholine binds to nicotinic receptors on the motor end plate membrane, increasing their permeability to Na⁺ and K⁺.
6. More Na⁺ moves into the fiber at the motor end plate than K⁺ moves out, depolarizing the membrane and producing the end - plate potential (EPP).
7. Local currents depolarize the adjacent muscle cell plasma membrane to its threshold potential.
8. A/An action potential is generated, which propagates along the skeletal muscle fiber surface and into the fiber along the T - tubules.
9. The conclusion of excitation at the neuromuscular junction involves acetylcholine degradation by acetylcholinesterase.