Table of Contents
- 1 What happens during falling phase?
- 2 What happens during the falling phase of an action potential?
- 3 What happens to the membrane potential during the repolarization phase of the action potential and what causes this change?
- 4 What happens during the rising phase of the action potential quizlet?
- 5 How is a concentration gradient established and maintained?
- 6 What happens to the membrane potential during the repolarization phase of the action potential and what causes this change quizlet?
- 7 What is the after hyperpolarization due to?
What happens during falling phase?
The falling phase is a rapid repolarization followed by the undershoot, when the membrane potential hyperpolarizes past rest. Finally, the membrane potential will return to the resting membrane potential.
What happens during the falling phase of an action potential?
The repolarization or falling phase is caused by the slow closing of sodium channels and the opening of voltage-gated potassium channels. As a result, the membrane permeability to sodium declines to resting levels. This expulsion acts to restore the localized negative membrane potential of the cell.
How does concentration gradient affect membrane potential?
For a cell where there is only one permeant ionic species (only one type of ion that can cross the membrane), the resting membrane potential will equal the equilibrium potential for that ion. The steeper the concentration gradient is, the larger the electrical potential that balances it has to be.
What happens to the membrane potential during the repolarization phase of the action potential and what causes this change?
In neuroscience, repolarization refers to the change in membrane potential that returns it to a negative value just after the depolarization phase of an action potential which has changed the membrane potential to a positive value. This phase occurs after the cell reaches its highest voltage from depolarization.
What happens during the rising phase of the action potential quizlet?
The rising phase of the action potential is due to an increase (x500) in membrane permeability to Na+. The increase in membrane permeability to K+ causes an after-hyperpolarisation. Voltage-activated Na+ and K+ channels confer the ability to generate action potentials.
What happens during the falling phase of the action potential quizlet?
The falling phase of the action potential results from closing sodium channels and opening potassium channels. Unlike sodium gates, potassium gates do not open immediately upon depolarization; it takes about 1 msec for them to open, and stay open as long as the membrane is depolarized.
How is a concentration gradient established and maintained?
Concentration gradients are generated and maintained across biological membranes by ion pump enzymes that transport ionic solutes such as sodium, potassium, hydrogen ions, and calcium across the membrane. Energy is required to produce a gradient, so the gradient is a form of stored energy.
What happens to the membrane potential during the repolarization phase of the action potential and what causes this change quizlet?
The repolarization phase of the action potential involves decreasing sodium influx via inactivation of sodium channels and increasing potassium efflux (exit) via opening potassium channels. Both of these processes begin near the peak of the action potential.
Why does hyperpolarization occur quizlet?
Why does hyperpolarization occur? The increase potassium ion permeability lasts slightly longer than the time required to bring the membrane potential back to its resting level.
What is the after hyperpolarization due to?
The slow after-hyperpolarization (AHP) in many cells, which follows bursts of action potentials, often results from the activation of calcium-dependent potassium currents flowing through SK channels.