WorksheetsPart 3 exam 3
Total questions: 17
Worksheet time: 9mins
Which statement best describes skeletal muscle excitability as noted in the lesson?
Skeletal muscles contract without any external signals.
Skeletal muscles are excitable and voluntary, requiring a signal from the brain to contract.
Skeletal muscles are inhibited by acetylcholine at rest.
Skeletal muscles maintain contraction without motor neurons.
At resting membrane potential (RMP), which ion concentrations are correctly positioned according to the notes?
High sodium inside the cell; high potassium outside
High sodium outside the cell; high potassium inside
Equal sodium and potassium on both sides
High calcium inside; high chloride outside
What mechanism maintains the concentration gradients that underlie the resting membrane potential in skeletal muscle?
Facilitated diffusion through sodium channels only
Secondary active transport via calcium pumps
Primary active transport using the sodium–potassium pump
Simple diffusion of potassium alone
According to the notes, the resting membrane potential remains approximately what value between the inside and outside of the cell?
+30 mV
0 mV
-70 mV
+90 mV
Which statement about the neuromuscular junction (NMJ) is correct?
It is a gapless fusion between neuron and muscle cell membranes.
It is the location where the axon terminal hovers over a muscle fiber across a fluid-filled synapse.
It is found only in cardiac muscle.
It is the site where sodium–potassium pumps are absent.
What is acetylcholine (ACh) characterized as in the notes?
A hormone that targets all tissues equally
A neurotransmitter and chemical message stored in synaptic vesicles and released by exocytosis to target skeletal muscle
An enzyme that breaks down sodium
A structural protein in sarcomeres
Based on the notes, which statement best captures the specificity of acetylcholine action here?
ACh can plug into any cell receptor in the body.
ACh really only targets skeletal muscle and can plug into muscle cell receptors.
ACh is inactive at the neuromuscular junction.
ACh targets only smooth muscle.
Which statement best describes a polarized membrane in a neuron or muscle cell?
The inside is more positive than the outside.
There is a separation of opposite charges; the inside is negative relative to the outside.
Sodium concentration is equal on both sides of the membrane.
Potassium channels are fully open at rest.
During depolarization of a muscle cell, which ion movement predominates and what happens to membrane potential?
Potassium efflux makes the interior more negative.
Sodium influx makes the interior more positive.
Calcium efflux makes the interior more positive.
Chloride influx makes the interior more negative.
Repolarization primarily results from which event?
Sodium channels opening, allowing sodium in
Potassium channels opening, allowing potassium out
Calcium channels opening at the terminal knob
Acetylcholine binding to intracellular receptors
What is the threshold potential noted for initiating an action potential in this material?
-70 mV
-55 mV
0 mV
+30 mV
According to the notes, what happens as soon as sodium floods into the cell and depolarizes it?
The cell remains depolarized for several seconds.
Calcium is pumped out to end the signal.
The cell must repolarize for the next signal, with potassium channels opening.
The threshold resets to a more negative value.
Which statement about the absolute refractory period is most accurate based on the notes?
It occurs before depolarization begins and allows stronger stimuli to trigger another action potential.
It occurs after hyperpolarization and the cell cannot accept another stimulus.
It is when sodium channels are most active and multiple stimuli sum.
It corresponds exactly to the resting membrane potential.
Which band is described as the dark band where thin and thick filaments overlap?
I Band
A Band
H Zone
Z disc
Identify the region that appears as the light band and contains thin filaments only in a relaxed muscle cell.
A Band
I Band
H Zone
M Line
Which area is the center portion of the bare zone within the A Band, with the exact center called the M Line?
Z disc
H Zone
I Band
A Band
Where is the Z disc located according to the notes?
At the center of the A Band
At the edges of thick filaments
Down the center of the I Band
Within the H Zone
