Question 1

Which of the following best describes the primary functional difference between chemical and electrical synapses?

Accepted Answer

Chemical synapses use neurotransmitters to transmit signals across a synaptic cleft, while electrical synapses transmit signals via gap junctions allowing direct ionic flow.

Question 2

A patient is experiencing muscle weakness due to a defect in the release of neurotransmitter at the neuromuscular junction. Which step in synaptic transmission is most likely impaired?

Accepted Answer

Opening of voltage-gated Ca$^{2+}$ channels in the presynaptic terminal

Question 3

Which of the following mechanisms does NOT contribute to the termination of neurotransmitter effects at a chemical synapse?

Accepted Answer

Continuous binding of neurotransmitter to postsynaptic receptors

Question 4

During an excitatory postsynaptic potential (EPSP), which of the following occurs at the postsynaptic membrane?

Accepted Answer

Chemically gated channels open, allowing Na$^+$ influx and K$^+$ efflux, resulting in depolarization.

Question 5

Which of the following best explains why synaptic delay is considered the rate-limiting step in neural transmission?

Accepted Answer

The process of neurotransmitter release, diffusion, and receptor binding takes longer than electrical conduction along the axon.

Question 6

A neuron receives simultaneous EPSPs and IPSPs from multiple presynaptic neurons. Which of the following will determine whether an action potential is generated?

Accepted Answer

The sum of all EPSPs and IPSPs at the axon hillock reaching threshold

Question 7

Which of the following is a characteristic unique to muscle tissue that allows it to return to its original length after being stretched?

Accepted Answer

Elasticity

Question 8

A researcher is studying a neuron that is electrically coupled to its neighbor via gap junctions. Which of the following is most likely true about this synapse?

Accepted Answer

It allows for rapid, bidirectional communication between neurons.

Question 9

Which of the following best describes the process of temporal summation at a synapse?

Accepted Answer

A single presynaptic neuron fires rapidly in succession, causing EPSPs to add together before dissipating.

Question 10

Which of the following is NOT a function of muscular tissue?

Accepted Answer

Transmitting nerve impulses

Question 11

A postsynaptic neuron is hyperpolarized after neurotransmitter binding. Which ion movement is most likely responsible for this inhibitory postsynaptic potential (IPSP)?

Accepted Answer

K$^+$ efflux or Cl$^-$ influx

Question 12

Which of the following best describes the structure of a skeletal muscle fiber?

Accepted Answer

A multinucleated, cylindrical cell containing myofibrils, glycogen, and myoglobin

Question 13

Which of the following scenarios best illustrates spatial summation in a postsynaptic neuron?

Accepted Answer

Multiple presynaptic neurons fire simultaneously, each producing an EPSP that adds together.

Question 14

Which of the following is TRUE regarding the sarcolemma of a muscle fiber?

Accepted Answer

It is the cell membrane of the muscle fiber and is capable of generating action potentials.

Question 15

A muscle fiber is described as a syncytium. What does this mean?

Accepted Answer

It is formed by the fusion of multiple cells, resulting in many nuclei.

Question 16

Which of the following best explains why a single EPSP is usually insufficient to trigger an action potential in a postsynaptic neuron?

Accepted Answer

EPSPs are local, graded depolarizations that must summate to reach threshold at the axon hillock.

Question 17

Which of the following is a real-life example of the importance of muscle tissue generating heat?

Accepted Answer

Shivering in response to cold temperatures

Question 18

If a postsynaptic neuron's membrane potential becomes more negative than the resting membrane potential after neurotransmitter binding, which of the following has occurred?

Accepted Answer

An inhibitory postsynaptic potential (IPSP)

Question 19

Which of the following best describes the role of the sarcoplasmic reticulum in muscle fibers?

Accepted Answer

It stores and releases Ca$^{2+}$ ions necessary for muscle contraction.

Cellular Physiology: Neuron and Muscle Structure & Function

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