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Questions and Answers
What is the resting membrane potential in neurons?
What is the resting membrane potential in neurons?
-70 mV
Which forces contribute to membrane potential?
Which forces contribute to membrane potential?
- Electrical gradient (correct)
- Concentration gradient (correct)
- Magnetic gradient
- Thermal gradient
The concentration gradient drives molecules from low to high concentration.
The concentration gradient drives molecules from low to high concentration.
False (B)
What is the main ion that has a positive electrical gradient forcing it into the neuron?
What is the main ion that has a positive electrical gradient forcing it into the neuron?
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How many potassium ions are pumped into the cell by the Na+/K+ pump?
How many potassium ions are pumped into the cell by the Na+/K+ pump?
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What helps establish the resting membrane potential?
What helps establish the resting membrane potential?
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Study Notes
Membrane Potentials
- At rest, axons are not propagating action potentials but maintain a resting membrane potential.
- Resting membrane potential is influenced by concentration gradients and electrical gradients of ions in intracellular and extracellular spaces.
Concentration and Electrical Gradients
- Diffusion force drives ions from areas of high concentration to low concentration.
- Electrical force drives ions from areas of high positive (+ve) charge to low negative (-ve) charge.
- Equilibrium potential occurs when electrical and concentration forces equalize, typically at -70mV in neurons.
Ion Concentration Gradients
- Major ions involved include Na+, K+, Ca2+, Cl-, and negatively charged proteins (OA-) in both intracellular and extracellular spaces.
- Na+ has a positive electrical and concentration gradient pushing it into the neuron, despite lower permeability through leak channels.
- K+ is more permeable due to a higher abundance of K+ leak channels, establishing the -70mV resting potential.
Na+/K+ Pump Mechanism
- The Na+/K+ pump transports 2 K+ ions into the cell and 3 Na+ ions out of the cell through active transport.
- This process requires energy in the form of ATP and moves ions against their concentration gradients.
Influence of Leak Channels
- K+ leak channels are more numerous than Na+ leak channels, resulting in greater resting permeability to K+.
- This differential permeability contributes significantly to the maintenance of the resting membrane potential.
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