Question

I have true for all of these, please check my answers.

49. When an action potential travels down an axon to the synaptic knob of a motor neuron innervating skeletal muscle, calcium enters the synaptic knob from the extracellular fluid through electrically gated channels. The entry of the calcium into the synaptic knob results in the release of acetylcholine from synaptic vesicles. T

50. Acetylcholine released from vesicles within the synaptic knob of a motor neuron diffuses across the synaptic cleft and binds to Acetylcholine receptors on the junctional folds of the sarcolemma at the motor endplate. T

51. The binding of acetylcholine to acetylcholine receptors on the sarcolemma is irreversible. T

52. The binding of acetylcholine to acetylcholine receptors results in sodium entering the muscle fiber and depolarizing the sarcolemma. As sodium enters the muscle fiber, potassium leaves the muscle fiberT

53. Following the depolarization of the sarcolemma at the motor endplate, the depolarization spreads along the sarcolemma to the T Tubules (This part of the statement is true.) As the depolarization spreads along the T Tubules, sodium is released from the sarcoplasmic reticulum. T

54. The binding of sodium to Troponin causes a conformational change in the Troponin-Tropomyosin complex that exposes the G-Actin active sites and allows myosin heads to bind.T

Answer 1

49. ANSWER: True.

Reason: Calcium causes the release of acetylcholin from presynaptic terminals.

50. ANSWER: True.

Reason: Acetylcholine binds to its receptors on the sarcolemma.

51. ANSWER: True

REASON: Acetylcholine irreversibly binds to its receptors.

52. ANSWER: True.

Reason: Sodium causes depolarisation at the neuromuscular junction.

53. ANSWER: FALSE.

REASON: As the depolarisation spreads through t tubules calcium ions are released.

54. ANSWER: FALSE.

Reason: The binding of calcium causes the troponin tropomyosin complex to expose the actin site.