Which of the following helps maintain the resting membrane potential of a neuron?Passive transportAdenosine triphosphateMembrane selective permeability

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11ecba2d_0fd1_4447_a3bf_6b2e59745d5f_MD0008_00 The unequal concentration of charged ions between the extracellular and intracellular fluid of all living cells results in an electrochemical gradient across the membrane that determines the membrane potential (voltage difference). The resting membrane potential of neurons is primarily due to the high concentration of potassium ions (K⁺) and the low concentration of sodium ions (Na⁺) inside the cell as compared to the outside. The following mechanisms contribute to maintenance of the resting membrane potential: Protein channels in the cell membrane enable certain ions to move down their concentration gradient across the membrane. For example, in resting neurons, potassium leak channels help maintain the membrane potential by enabling the passive transport (without using energy) of K⁺ out of the cell. Because the membrane is more permeable to K⁺ than to Na⁺ (ie, selective permeability), the resting membrane potential of neurons is approximately −70 mV, which is close to the negative equilibrium potential of K⁺ (Numbers I and III). Active transport pumps embedded in the outer membrane of neurons hydrolyze adenosine triphosphate (ATP) to provide energy to transport molecules against their concentration gradient. For example, sodium-potassium pumps (Na⁺K⁺ ATPase) transport 2 K⁺ into the cell for every 3 Na⁺ moved out of the cell. This is important for maintaining the unequal concentration of ions across the membrane; without active transport pumps, leakage of ions through the cell membrane would eventually result in equilibration and a membrane potential of 0 mV (Number II). Educational objective: The presence of protein channels in the cell membrane allows passive transport of certain ions down their electrochemical gradient. This selective membrane permeability is responsible for generating the resting membrane potential in nerve and muscle cells. Active transport pumps help maintain the concentration gradient and are critical for maintaining the resting membrane potential.

Which of the Following Helps Maintain the Resting Membrane Potential