Nervous System 2

Question 1

The resting potential

Answer 1

-Membrane potential when neuron is not firing
-Inside of membrane is more electronegative
-Outside of membrane is defined as 0 mV

Question 2

The resting potential is determined by several transmembrane proteins

Answer 2

1. Potassium (K+) leak channels
2. Sodium ion (Na+) voltage-gated channels
3. Potassium (K+) voltage-gated channels
4. proton pumps

Question 3

Potassium (K+) leak channel

Answer 3

allows K+ to leak across cell membrane

Question 4

Sodium ion voltage-gated channel

Answer 4

-Open or closed depends on difference in electric charge across cell membrane (Membrane potential)
-Closed: Na+ cannot cross neuron’s membrane
-Open: Na+ can cross the neuron’s membrane

Question 5

Proton pump

Answer 5

-Causes inside of neuron to become more electronegative

Question 6

Why is the inside more electronegative?

Answer 6

-Na+ voltage-gated channels are closed
-K+ voltage-gated channels are closed
-Proton pump trades 3 (Na+) positively charged ions for 2 (K+)
-This leads to fewer positive charges on the inside of the neuron
-inside is more electronegative

Question 7

Why is the inside more electronegative?

Answer 7

-K+ can cross leaky channels
-Concentration gradient favors net export of K+
-Electrochemical gradient favors net import of K+
-This voltage is called the equilibrium gradient of K+

Question 8

At a neuron’s resting potential .

Answer 8

the cell membrane is more electronegative on the inside than the outside

Question 9

Action potential

Answer 9

A rapid change in electrical potential across a cell membrane.

Question 10

Threshold potential

Answer 10

Membrane potential that will trigger an action potential