When an action potential arrives at the neuromuscular junction, acetylcholine is released into the synaptic cleft and binds to receptors in the postsynaptic membrane. Which of the following represents the correct order of the next series of events?   A. An action potential travels down the T tubules, depolarization spreads through the T tubules, Ca2+ is released from the sarcoplasmic reticulum, and myosin binds to actin.   B. Ca2+ is released from the sarcoplasmic reticulum, an action potential travels down the T tubules, depolarization spreads through the T tubules, and myosin binds to actin.   C. An action potential travels down the T tubules, depolarization spreads through the T tubules, Ca2+ is taken up by the sarcoplasmic reticulum, and myosin binds to actin.   D. T tubules are depolarized, Ca2+ is released from the sarcoplasmic reticulum, an action potential is created in the muscle cell, and myosin bonds to actin.   E. An action potential travels down the T tubules, depolarization spreads through the T tubules, ATP binds to troponin, and myosin binds to actin.

Acetylcholinesterase is an important molecule in the engine end plate to share: a) stimulates receptors in the postsynaptic membrane b) synthesizes acetylcholine from acetate and choline c) breaks down acetylcholine d) stimulates the release of Ca2 + from the sarcoplasmic reticulum

are these True or False? Receptors on the post-synaptic cell membrane that bind the acetylcholine are voltage-gated channels (channels that open in response to a change in the electrical charge of the membrane). When a muscle cell is not contracting its cell membrane is negative on the inner surface. The effect of a neurotransmitter on the muscle cell membrane is to modify its ion permeability properties temporarily.

hen an action potential arrives at the nerve terminal of a neuromuscular junction, which of the following statements best describes the events that occur?     Depolarisation of the nerve terminal causes the release of ACh which activates nicotinic receptors on the skeletal muscle membrane to cause Ca2+ entry and muscle contraction.     Depolarisation of the nerve terminal opens voltage-gated Ca2+ channels, Ca2+ entry brings vesicles containing ACh to the membrane which form fusion pores causing the release of ACh which activates voltage-gated Na+ channels at the end-plate.     Depolarisation of the nerve terminal opens voltage-gated Ca2+ channels, Ca2+ entry brings vesicles containing ACh to the membrane which form fusion pores causing the release of ACh which binds to muscarinic receptors at the end plate.     Depolarisation of the nerve terminal opens voltage-gated Ca2+ channels, Ca2+ entry brings vesicles containing ACh to the membrane which form fusion pores…