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Set 3 6 Neuromuscular Junction And Ec Coupling

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Question 1

(Multiple Choice)

Free
If we excite a motor neuron to fire an action potential in the presence of EGTA to complex all of the Ca2+

A) Acetylcholine release will be reduced and the EPP will be reduced, but the muscle will
contract
B) Neurotransmission will be unaffected but contraction will be blocked because it requires Ca2+
C) Neurotransmission will be blocked and so there will be no contraction
D) Neurotransmission block can be overcome by repetitive stimulation
E) The neuron cannot fire an action potential in the absence of Ca2+

Answer

Question 2

(Multiple Choice)

Free
A nerve has a resting m embrane potential of -70 m V. ECl = -80 mV; EK = -95 mV and ENa = +65 mV. Increasing gCl should produce

A) An inward current and an EPSP
B) An outward current and an EPSP
C) An inward current and an IPSP
D) An outward current and an IPSP
E) It is impossible to tell from the information given

Answer

Question 3

(Multiple Choice)

Free
Relaxation of skeletal muscle is caused by

A) Reuptake of activator Ca2+ by the SR Ca-ATPase pump
B) Efflux of Ca2+ into the extracellular space
C) Uptake of activator Ca2+ into the mitochondria
D) Closing of the ryanodine-sensitive Ca2+channel
E) Binding of Ca2+ to calsequestrin

Answer