Neurophysiology 1: Membrane Potential, Synapse, Muscle

Question 1

What is the resting membrane potential?

Answer 1

-70 mV

Question 2

What kind of membrane does a neuron have?

Answer 2

phospholipid bilayer

Question 3

What does the Gibbs-Donnan Equilibrium tell us?

Answer 3

There is a continued asymmetry because of the existence of impermeable ions (i.e. proteins). These negative proteins repel CL- to go out the cell, causing an imbalance.

Question 4

What does the Nernst Equation compute for?

Answer 4

solves for aby diffusable ion’s equilibrium potential

Question 5

According to the Nernst Equation, what are the equilibrium potential of K, Na, and Cl?

Answer 5

1. K = -90mV
2. Na = +60mV
3. Cl = -70mV

Question 6

What is the mechanism of the sodium potassium pump?

Answer 6

3 Na out + 2 K in

Question 7

What does the goldman constant field equation tell us?

Answer 7

more generalized version of the nernst equation. It takes into account all the ions

Question 8

Action potential originates where?

Answer 8

axon

Question 8

How is action potential different from local potential?

Answer 8

Action Potential: all or nothing (-55mV)
Local Potential: depends on the strength of stimulus

Question 9

-Local potential originates where?

Answer 9

dendrites

Question 10

What is the threshold for action potential to occur?

Answer 10

-55mV

Question 11

What is the basic contractile unit of a muscle fiber?

Answer 11

sacromere

Question 12

What are the parts of a sacromere?

Answer 12

1. Z disk: anchors actin (thin) + connect adj. sacromere
2. A band: dark region, contain myosin, constant length during contraction
3. I band: light region, contains actin, shorten during contraction
4. H zone: visible when muscle is relaxed
5. M line: hold thick filament (myosin) in place
6. Titin: “spring” to restore sacromere to resting length after contraction/stretching