Q: Which equation is used to calculate the equilibrium potential for a single ion across a membrane, and what is the formula?

The Nernst equation: $$E = \frac{RT}{zF} \ln \left( \frac{[\text{ion}]_{\text{outside}}}{[\text{ion}]_{\text{inside}}} \right)$$

Question 1

Which of the following best describes the function of the plasma membrane in a typical human cell?

Accepted Answer

It selectively regulates the movement of substances into and out of the cell, maintaining homeostasis.

Question 2

A patient is given an intravenous solution that is hypertonic relative to their blood plasma. What is the most likely effect on their red blood cells?

Accepted Answer

The red blood cells will shrink as water leaves the cells to balance the osmotic gradient.

Question 3

Which equation is used to calculate the equilibrium potential for a single ion across a membrane, and what is the formula?

Accepted Answer

The Nernst equation: $$E = \frac{RT}{zF} \ln \left( \frac{[	ext{ion}]_{	ext{outside}}}{[	ext{ion}]_{	ext{inside}}} ight)$$

Question 4

Which of the following best explains why the resting membrane potential of a neuron is closer to the equilibrium potential of potassium ($$K^+) $$than sodium ($$Na^+$$)?

Accepted Answer

The membrane is more permeable to $$K^+$$ ions than to $$Na^+$$ ions at rest.

Question 5

A mutation causes the voltage-gated sodium channels in a neuron to remain open longer than normal during an action potential. What is the most likely effect on the action potential?

Accepted Answer

The depolarization phase will be prolonged, potentially increasing the risk of repetitive firing.

Question 6

Which of the following best describes the difference between absolute and relative refractory periods in neurons?

Accepted Answer

During the absolute refractory period, no new action potential can be generated, while during the relative refractory period, a stronger-than-normal stimulus is required to generate an action potential.

Question 7

Which of the following is a correct comparison between symporters and antiporters in secondary active transport?

Accepted Answer

Symporters move two substances in the same direction across the membrane, while antiporters move two substances in opposite directions.

Question 8

A patient is diagnosed with multiple sclerosis. Which of the following best describes the underlying cause of this disease?

Accepted Answer

Destruction of the myelin sheath in the central nervous system due to an autoimmune response.

Question 9

Which of the following best describes the effect of increasing extracellular potassium ($$K^+) $$concentration on the resting membrane potential of a neuron?

Accepted Answer

The resting membrane potential becomes less negative (depolarizes).

Question 10

Which of the following is a function of the sodium-potassium pump ($$Na^+/K^+-$$ATPase) in maintaining the resting membrane potential?

Accepted Answer

It actively transports 3 $$Na^+$$ ions out of the cell and 2 $$K^+$$ ions into the cell, using ATP.

Question 11

Which of the following best describes the role of neurotransmitter reuptake in synaptic transmission?

Accepted Answer

It removes neurotransmitters from the synaptic cleft, terminating the signal.

Question 12

Which of the following is a key difference between electrical and chemical synapses?

Accepted Answer

Electrical synapses transmit signals via gap junctions, allowing direct ion flow, while chemical synapses use neurotransmitters to transmit signals across a synaptic cleft.

Question 13

Which of the following best explains why action potentials travel faster in myelinated axons compared to non-myelinated axons?

Accepted Answer

Myelination allows for saltatory conduction, where the action potential jumps between nodes of Ranvier.

Question 14

Which of the following best describes the effect of opening ligand-gated chloride ($$Cl^-) $$channels on the postsynaptic membrane?

Accepted Answer

It causes hyperpolarization, making the postsynaptic neuron less likely to fire an action potential.

Question 15

Which of the following is a correct statement about the Goldman-Hodgkin-Katz (GHK) equation?

Accepted Answer

It calculates the membrane potential by considering the permeability and concentration gradients of multiple ions.

Question 16

Which of the following best describes the process of exocytosis in neurons?

Accepted Answer

Vesicles containing neurotransmitters fuse with the presynaptic membrane to release their contents into the synaptic cleft.

Question 17

Which of the following is a major difference between ionotropic and metabotropic neurotransmitter receptors?

Accepted Answer

Ionotropic receptors are ligand-gated ion channels that mediate fast synaptic transmission, while metabotropic receptors are G-protein-coupled and mediate slower, modulatory effects.

Question 18

Which of the following best describes the phenomenon of long-term potentiation (LTP) at a glutamatergic synapse?

Accepted Answer

A persistent increase in synaptic strength following high-frequency stimulation, involving increased $$Ca^{2+}$$ influx and activation of NMDA receptors.

Question 19

Which of the following best describes the effect of a competitive antagonist at a neurotransmitter receptor?

Accepted Answer

It binds to the receptor and prevents the neurotransmitter from activating it.

Question 20

Which of the following is a correct description of the difference between graded potentials and action potentials?

Accepted Answer

Graded potentials vary in amplitude and can summate, while action potentials are all-or-none events that propagate without decrement.

Cellular Physiology and Neurophysiology: Study Guide for Exam Preparation

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