The Nervous System: Neurophysiology of Nerve Impulses
Session 9: The Nervous System - Assignment #2
PhysioEx Assignment : Exercise 3 Neurophysiology of Nerve Impulses
Activity 1: The Resting Membrane Potential
1. Explain why increasing extracellular K+ reduces the net diffusion of K+ out of the neuron through the K+ leak channels.
Increasing the extracellular K+ causes the membrane potential to change to a less negative value because when K+ ions diffuse out across the membrane they are leaving behind a net negative charge.
2. Explain why increasing extracellular K+ causes the membrane potential to change to a less negative value.
Potassium ions diffuse out across the membrane, leaving behind a net negative charge.
3. Explain why a change in extracellular Na+ did not alter the membrane potential in the resting neuron.
There are less leakage sodium channels than leakage potassium channels, and more of the potassium channels are open.
4. Discuss the relative permeability of the membrane to Na+ and K+ in a resting neuron.
Membrane permeability to sodium is very low because there are only a few sodium leakage channels. Sodium ions do slowly diffuse inward, down their concentration gradient. Left unchecked, such inward leakage of sodium would eventually destroy the resting membrane potential. The sodium potassium pumps offset the small inward sodium leak and outward leak of potassium leak.
5. Discuss how a change in NA+ or K+ conductance would affect the resting membrane potential.
The resting period potential is a potential difference between the inside of the cell and the outside of the cell across the membrane. It depends on the resting permeability of the membrane to ions and on the intracellular and extracellular concentrations of those ions to which the membrane is permeable.
Activity 2: Receptor Potential
1. Sensory neurons have a resting potential based on the efflux of potassium ions. What passive channels are likely found in the membrane of the olfactory receptor, in
PhysioEx Assignment : Exercise 3 Neurophysiology of Nerve Impulses
Activity 1: The Resting Membrane Potential
1. Explain why increasing extracellular K+ reduces the net diffusion of K+ out of the neuron through the K+ leak channels.
Increasing the extracellular K+ causes the membrane potential to change to a less negative value because when K+ ions diffuse out across the membrane they are leaving behind a net negative charge.
2. Explain why increasing extracellular K+ causes the membrane potential to change to a less negative value.
Potassium ions diffuse out across the membrane, leaving behind a net negative charge.
3. Explain why a change in extracellular Na+ did not alter the membrane potential in the resting neuron.
There are less leakage sodium channels than leakage potassium channels, and more of the potassium channels are open.
4. Discuss the relative permeability of the membrane to Na+ and K+ in a resting neuron.
Membrane permeability to sodium is very low because there are only a few sodium leakage channels. Sodium ions do slowly diffuse inward, down their concentration gradient. Left unchecked, such inward leakage of sodium would eventually destroy the resting membrane potential. The sodium potassium pumps offset the small inward sodium leak and outward leak of potassium leak.
5. Discuss how a change in NA+ or K+ conductance would affect the resting membrane potential.
The resting period potential is a potential difference between the inside of the cell and the outside of the cell across the membrane. It depends on the resting permeability of the membrane to ions and on the intracellular and extracellular concentrations of those ions to which the membrane is permeable.
Activity 2: Receptor Potential
1. Sensory neurons have a resting potential based on the efflux of potassium ions. What passive channels are likely found in the membrane of the olfactory receptor, in