Q: A neuron’s resting membrane potential is primarily determined by which of the following?

The relative permeability of the membrane to Na\textsuperscript{+} and K\textsuperscript{+}, with greater permeability to K\textsuperscript{+}.

Q: Which of the following best describes the role of the Na\textsuperscript{+}-K\textsuperscript{+}-ATPase in maintaining membrane potential?

It actively transports 3 Na\textsuperscript{+} out and 2 K\textsuperscript{+} in, helping maintain the negative resting membrane potential.

Q: Which of the following would most likely result in a hyperpolarizing graded potential in a neuron?

Opening of chemically gated Cl\textsuperscript{−} channels

Question 1

Which of the following best explains why homeostasis does NOT mean equilibrium in the human body?

Accepted Answer

Homeostasis maintains a stable internal environment, but the intracellular and extracellular fluids are in chemical and electrical disequilibrium.

Question 2

A patient is given an intravenous (IV) solution containing 1 mole of NaCl per liter. What is the osmolarity of this solution, and why?

Accepted Answer

2 osmol/L, because each NaCl molecule dissociates into two particles: Na	extsuperscript{+} and Cl	extsuperscript{−}.

Question 3

A 58-kg reference woman has a total body water content of 50% of her body weight. Calculate her total body water volume in liters.

Accepted Answer

$$58 	imes 0.5 = 29$$ liters

Question 4

Which of the following best describes the effect of a solution that is hypertonic to a red blood cell?

Accepted Answer

The cell will shrink as water moves out.

Question 5

A neuron’s resting membrane potential is primarily determined by which of the following?

Accepted Answer

The relative permeability of the membrane to Na	extsuperscript{+} and K	extsuperscript{+}, with greater permeability to K	extsuperscript{+}.

Question 6

Using the Nernst equation $$E_{ion} = \frac{61}{z} \log \left( \frac{[ion]_{out}}{[ion]_{in}} ight)$$, what is the equilibrium potential for K	extsuperscript{+} if $$[K^+]_{out} = 5 mM $$and $$[K^+]_{in} = 150 mM$?$$

Accepted Answer

$$E_{K^+} = \frac{61}{+1} \log \left( \frac{5}{150} \right) \approx -90 mV$$

Question 7

A patient is exposed to ouabain, a poison that inhibits the Na	extsuperscript{+}-K	extsuperscript{+}-ATPase. What is the most likely effect on the neuron’s resting membrane potential?

Accepted Answer

The resting membrane potential will become less negative (depolarized) over time.

Question 8

Which of the following is TRUE regarding the difference between osmolarity and tonicity?

Accepted Answer

Tonicity depends on both the concentration and the nature of solutes, while osmolarity is a numerical measure of all solute particles.

Question 9

A solution contains 1 mole of glucose and 1 mole of NaCl per liter. What is the total osmolarity of this solution?

Accepted Answer

3 osmol/L

Question 10

Which of the following best describes the role of the Na	extsuperscript{+}-K	extsuperscript{+}-ATPase in maintaining membrane potential?

Accepted Answer

It actively transports 3 Na	extsuperscript{+} out and 2 K	extsuperscript{+} in, helping maintain the negative resting membrane potential.

Question 11

Which of the following would most likely result in a hyperpolarizing graded potential in a neuron?

Accepted Answer

Opening of chemically gated Cl	extsuperscript{−} channels

Question 12

Which of the following is a property of action potentials but NOT graded potentials?

Accepted Answer

They are all-or-none events that propagate without losing strength.

Question 13

A mutation causes a neuron to have fewer voltage-gated K	extsuperscript{+} channels. What is the most likely effect on the action potential?

Accepted Answer

The falling phase will be slower, and repolarization will be delayed.

Question 14

Which of the following best explains why myelinated axons conduct action potentials faster than unmyelinated axons?

Accepted Answer

Myelin increases membrane resistance and decreases capacitance, allowing saltatory conduction.

Question 15

Which of the following is a direct effect of blocking voltage-gated Na	extsuperscript{+} channels with tetrodotoxin?

Accepted Answer

Action potentials cannot be initiated or propagated.

Question 16

Which neurotransmitter is the primary excitatory neurotransmitter in the central nervous system?

Accepted Answer

Glutamate

Question 17

Which of the following best describes the mechanism of action for G protein-coupled receptors (GPCRs) in neurotransmission?

Accepted Answer

They transduce signals through second messengers, resulting in slower, longer-lasting effects.

Question 18

A patient with myasthenia gravis has muscle weakness due to an autoimmune attack on which of the following?

Accepted Answer

Acetylcholine receptors at the neuromuscular junction

Human Physiology: Membrane Dynamics, Electrical Signaling, and Neurotransmission

Study Guide - Practice Questions

Study Guide - Flashcards