Question 1

Which of the following best explains why chemical synapses are slower than electrical synapses?

Accepted Answer

Chemical synapses require neurotransmitter release and receptor binding, which introduces a synaptic delay.

Question 2

A patient is exposed to a toxin that blocks voltage-gated Ca$$^{2+}$$ channels at the axon terminal. What is the most likely effect on synaptic transmission?

Accepted Answer

Neurotransmitter release will be inhibited, preventing postsynaptic activation.

Question 3

Which neurotransmitter is the primary excitatory transmitter in the central nervous system, and what ion movement does it cause at the postsynaptic membrane?

Accepted Answer

Glutamate; Na$$^+$$ influx and K$$^+$$ efflux, resulting in net depolarization.

Question 4

A neuron receives multiple excitatory postsynaptic potentials (EPSPs) from different presynaptic neurons at the same time. What is this process called?

Accepted Answer

Spatial summation

Question 5

Which of the following best describes the function of acetylcholinesterase at the neuromuscular junction?

Accepted Answer

It breaks down acetylcholine, terminating the signal and allowing muscle relaxation.

Question 6

Which type of muscle contraction occurs when muscle tension increases but the muscle does not change length?

Accepted Answer

Isometric contraction

Question 7

A patient is given curare during surgery. What is the expected effect at the neuromuscular junction?

Accepted Answer

Curare blocks nicotinic acetylcholine receptors, preventing muscle contraction.

Question 8

Which neural circuit pattern is most likely responsible for the rhythmic breathing movements generated in the brainstem?

Accepted Answer

Reverberating circuit

Question 9

Which of the following best explains why small motor units are recruited before large motor units during muscle contraction?

Accepted Answer

Small motor units have lower activation thresholds, allowing fine control before generating large force.

Question 10

Which of the following metabolic pathways provides the most ATP per glucose molecule for muscle contraction?

Accepted Answer

Aerobic respiration

Question 11

A patient with myasthenia gravis experiences muscle weakness that worsens with use. What is the underlying mechanism?

Accepted Answer

Autoantibodies destroy acetylcholine receptors at the neuromuscular junction.

Question 12

Which of the following is a characteristic of unitary (visceral) smooth muscle?

Accepted Answer

Cells are connected by gap junctions and contract as a unit.

Question 13

Which neurotransmitter is most likely to cause an inhibitory postsynaptic potential (IPSP) in the brain, and by what mechanism?

Accepted Answer

GABA; opening Cl$$^-$$ channels, leading to hyperpolarization.

Question 14

Which of the following best describes the role of Ca$$^{2+} in $$smooth muscle contraction?

Accepted Answer

Ca$$^{2+}$$ binds to calmodulin, activating myosin light chain kinase to initiate contraction.

Question 15

A muscle fiber is stimulated repeatedly at a high frequency, resulting in a smooth, sustained contraction with no relaxation. What is this phenomenon called?

Accepted Answer

Fused (complete) tetanus

Question 16

Which of the following best explains why smooth muscle is more resistant to fatigue than skeletal muscle?

Accepted Answer

Smooth muscle uses less ATP and can maintain tension with latch-bridges.

Question 17

Which of the following is true regarding the effect of neurotransmitters at a synapse?

Accepted Answer

The effect (excitatory or inhibitory) depends on the type of receptor present on the postsynaptic cell.

Question 18

Which neural circuit type is most likely to amplify a signal from a single sensory neuron to multiple regions of the brain?

Accepted Answer

Diverging circuit

Question 19

A person is holding a heavy box without moving their arms. Which type of muscle contraction is primarily occurring in their biceps?

Accepted Answer

Isometric contraction

Question 20

Which of the following best describes the process of temporal summation in neurons?

Accepted Answer

Multiple EPSPs from a single presynaptic neuron occur in rapid succession, adding together in time.

Membrane Transport & Excitable Cells: Synaptic Transmission and Muscle Contraction

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