WK 11 Synapses: Postsynaptic Dynamics

At the neuromuscular junction, why is the current inward at -110 mV

• The channel is not permeable K+

• The channel is only permeable to Na+

• The channel is permeable to Na+ and K+ but Vm is at ENa

• The channel is permeable to K+ and Na+ but Vm is at EK

• none of these is correct

Which statement regarding metabotropic and ionotropic receptors is true?

• Metabotropic receptors open channels faster than ionotropic receptors do.

• Ionotropic receptors have immediate effects; metabotropic receptors produce long-term effects.

• Both directly allow ion flow through an ion pore in the receptor.

• Metabotropic and ionotropic receptors act via the same mechanisms; the difference is the neurotransmitters that activate them.

• Ionotropic receptors require the activation of intracellular messengers.

At the neuromuscular junction, why is the current outward at 70 mV

• The channel is not permeable K+

• The channel is only permeable to Na+

• The channel is permeable to Na+ and K+ but Vm is at ENa

• The channel is permeable to K+ and Na+ but Vm is at EK

• none of these is correct

At –10 mV, end plate current is _______ in amplitude and directed _______.

• small; inward

• small; outward

• large; inward

• large; outward

• None of the above

Which observation would indicate a role for calcium in transmitter secretion?

• Observation of presynaptic depolarizing currents after blockade of sodium channels

• Voltage clamp experiments showing voltage-gated calcium channels in the presynaptic terminal

• Induction of transmitter release by injection of calcium into the presynaptic terminal

• Blockade of transmitter release by injection of calcium blocker into the presynaptic terminal

• All of the above