Multiple Choice
Which of the following correctly lists the three main types of neurons found in the human nervous system?
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45. Nervous System
Neurons and Action Potentials
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What effect does increasing the extracellular potassium concentration have on the resting membrane potential of a neuron?
A
It makes the resting membrane potential more negative (hyperpolarizes the membrane).
B
It causes the neuron to fire an action potential immediately.
C
It makes the resting membrane potential less negative (depolarizes the membrane).
D
It has no effect on the resting membrane potential.
Verified step by step guidance1
Understand the concept of resting membrane potential: The resting membrane potential is the electrical charge difference across the neuron's membrane when the neuron is not actively sending signals. It is primarily determined by the distribution of ions, such as potassium (K⁺) and sodium (Na⁺), across the membrane.
Recognize the role of potassium ions (K⁺): Potassium ions play a major role in establishing the resting membrane potential. The membrane is more permeable to K⁺ than other ions, and K⁺ tends to move out of the cell down its concentration gradient, leaving the inside of the cell more negative.
Analyze the effect of increasing extracellular potassium concentration: When extracellular potassium concentration increases, the concentration gradient for K⁺ across the membrane decreases. This reduces the driving force for K⁺ to leave the cell, causing fewer positive charges to exit the cell.
Relate the change in ion movement to the resting membrane potential: With fewer positive charges leaving the cell, the inside of the neuron becomes less negative compared to its usual resting state. This results in depolarization, meaning the resting membrane potential becomes less negative.
Conclude the effect: Increasing extracellular potassium concentration depolarizes the membrane, making the resting membrane potential less negative. This is because the reduced potassium gradient alters the balance of ion movement across the membrane.
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