Question

Na+-K+ pump n generation of the transmembrane (resting) potential

Answer 1

The resting membrane potential, typically around -70 mV, is maintained by the Na+-K+ pump which creates gradients of Na+ and K+ ions and results in a net negative charge inside the neuron. Sodium-potassium pumps use ATP to transport ions, setting the stage for action potentials in neurons.

Step-by-step explanation:

The Role of the Na+-K+ Pump in Generating Resting Membrane Potential

The resting membrane potential is a crucial aspect of a neuron's ability to conduct electrical signals. This potential is generated and maintained by the Na+-K+ ATPase, also known as the sodium-potassium pump. This active transport mechanism uses ATP to pump three Na+ ions out of the cell and two K+ ions into the cell against their concentration gradients. This creates both a chemical and an electrical gradient across the cell membrane. While K+ ions can leave the cell through leakage channels, leading to a net negative charge inside, Na+ ions cannot easily enter because Na+ channels are rarely open in the resting state.

At a resting potential, there is a large concentration gradient for Na+ to enter the cell and an accumulation of negative charges within the cell. This results in a typical resting membrane potential of approximately -70 mV, where the inside of the cell is negatively charged compared to the outside. The Na+-K+ pump and selective permeability of ion channels are essential for maintaining this -70 mV potential, which is vital for the functionality of neurons.

Answer 2

The Na+-K+ pump establishes the resting membrane potential by moving ions across the cell membrane using ATP. This creates a concentration gradient and a negative charge inside the cell, typically at -70 mV. The pump maintains this gradient, essential for cell excitability and function.

Step-by-step explanation:

Understanding the Role of the Na+-K+ Pump in Generating Resting Membrane Potential

The Na+-K+ pump, also known as the sodium-potassium ATPase, plays a crucial role in establishing the resting membrane potential of a cell. This active transport mechanism uses ATP to move three Na+ ions out of the cell and two K+ ions into the cell, creating a concentration gradient across the cell membrane with more Na+ outside and more K+ inside the cell.

Potassium ions can leave the cell via K+ channels that are open most of the time, while Na+ channels remain mostly closed. This ion movement results in a net negative charge within the cell, as the positively charged K+ ions exit, leaving behind the fixed anions. The separation of electrical charge across the membrane, capable of doing work, is measured in millivolts (mV).

Typically, the resting membrane potential is around -70 mV, indicating the internal negativity relative to the outside environment. This state is essential for the function of neurons and muscle cells, setting the stage for the generation of action potentials in response to stimuli. It's important to note that despite ion leakage, which causes a slight shift in membrane potential, the Na+-K+ pump works persistently to restore the ion balance, maintaining the resting potential.

During excitation of the cell, voltage-gated Na+ and K+ channels open in response to specific stimuli, allowing for rapid changes in ion concentrations and leading to membrane depolarization and repolarization, which are phases of an action potential. The Na+-K+ pump restores the ion distribution after each action potential, thereby ensuring the cell is ready for the next stimulus.

Finally, myelinated neurons feature saltatory conduction, where action potentials significantly speed up by 'jumping' between nodes of Ranvier. This optimization is crucial for the rapid transmission of nerve impulses throughout the body.