Q: Which equation correctly represents the action of the sodium-potassium exchange pump in neurons?

$$2\ \mathrm{K^+}_{\text{out}} + 3\ \mathrm{Na^+}_{\text{in}} + \text{ATP} \rightarrow 2\ \mathrm{K^+}_{\text{in}} + 3\ \mathrm{Na^+}_{\text{out}} + \text{ADP} + \text{P}_i$$

Question 1

Which of the following best describes the 'all-or-none principle' of action potentials in neurons?

Accepted Answer

Any stimulus that depolarizes the membrane to threshold will trigger an action potential of the same magnitude.

Question 2

A neuron is exposed to a chemical that blocks voltage-gated sodium ($$\mathrm{Na^+}) $$channels. What is the most likely effect on the generation of an action potential?

Accepted Answer

The neuron will be unable to depolarize to threshold, preventing action potential initiation.

Question 3

During the repolarization phase of an action potential, which ion movement is primarily responsible for returning the membrane potential toward resting levels?

Accepted Answer

Efflux of $$\mathrm{K^+}$$ ions

Question 4

Which of the following statements about graded potentials is TRUE?

Accepted Answer

Graded potentials diminish in strength as they spread from the site of stimulation.

Question 5

A patient is experiencing muscle weakness due to a lack of acetylcholine (ACh) release at the neuromuscular junction. Which step in synaptic transmission is most likely impaired?

Accepted Answer

Exocytosis of ACh from presynaptic vesicles

Question 6

Which type of axon would transmit sensory information about pain the slowest?

Accepted Answer

Type C fiber

Question 7

Saltatory propagation of an action potential is characterized by:

Accepted Answer

Action potential jumping from one node of Ranvier to the next, increasing speed and efficiency.

Question 8

Which equation correctly represents the action of the sodium-potassium exchange pump in neurons?

Accepted Answer

$$2\ \mathrm{K^+}_{	ext{out}} + 3\ \mathrm{Na^+}_{	ext{in}} + 	ext{ATP} ightarrow 2\ \mathrm{K^+}_{	ext{in}} + 3\ \mathrm{Na^+}_{	ext{out}} + 	ext{ADP} + 	ext{P}_i$$

Question 9

Which neurotransmitter is primarily associated with inhibitory effects in the central nervous system?

Accepted Answer

Gamma-aminobutyric acid (GABA)

Question 10

A neuron receives simultaneous excitatory and inhibitory inputs. What determines whether it will fire an action potential?

Accepted Answer

The net effect of all EPSPs and IPSPs at the axon hillock

Question 11

Which of the following best explains why synaptic delay occurs at chemical synapses?

Accepted Answer

Calcium ion influx and neurotransmitter release require time.

Question 12

Which process describes the rapid, repeated stimulation at a single synapse leading to summation?

Accepted Answer

Temporal summation

Question 13

Which of the following is a direct effect of neurotransmitters such as acetylcholine (ACh) on postsynaptic membranes?

Accepted Answer

Opening of chemically gated ion channels

Question 14

Which of the following would most likely result in presynaptic inhibition?

Accepted Answer

A decrease in neurotransmitter release from the presynaptic neuron

Question 15

Which of the following neurotransmitters is classified as a biogenic amine and is involved in attention and emotional states?

Accepted Answer

Serotonin

Question 16

A neuron is said to be 'facilitated' when:

Accepted Answer

EPSPs have raised the membrane potential closer to threshold, making it easier to trigger an action potential.

Question 17

Which of the following is TRUE regarding the propagation speed of action potentials in axons?

Accepted Answer

Myelinated axons conduct action potentials faster than unmyelinated axons.

Question 18

Which of the following is a neuromodulator that binds to the same receptors as opium and morphine?

Accepted Answer

Enkephalins

Question 19

Which of the following best describes the effect of inhibitory neurotransmitters on the postsynaptic membrane?

Accepted Answer

They cause hyperpolarization and suppress action potentials.

Nervous Tissue: Membrane Potentials, Action Potentials, and Synaptic Transmission

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