2. Neuromuscular junction and somatic motor signaling

At the neuromuscular junction, a motor-neuron action potential causes _.

acetylcholine release

Acetylcholine binds a high density of _ receptors on the _.

nicotinic acetylcholine, motor end plate

nicotinic acetylcholine receptors are (3 things)

ligand gated, nonselective cation channels, reversal potential near 0mV

opening nicotinic acetylcholine receptors

depolarizes the muscle membrane from its resting negative potential

The motor end plate has a large number of _ which_.

nicotinic acetylcholine receptors, makes transmission reliable

ACh binding opens the nicotinic channel, allowing _.

Na+ to flow in and K+ to flow out, however, since the membrane potential (-90mV) is so much lower than the receptor’s reversal potential (-0mV) this means that Na+ is going to enter at a must faster rate then K+ is leaving. This means that the cell is being depolarized

The end-plate depolarization reaches threshold and triggers an action potential that _.

spreads across the sarcolemma and into the T-tubules

A agonist

usually mimics the normal transmitter (ACh)

Antagonist (muscarinic blockers) effects on and pupil, gland, and heart findings

agonist/antagonist pupil: causes constriction/dilation

agonist/antagonist glands: causes sweat/dryness

agonist/antagonist heart: causes decreased heart rate/increased heart rate