Action Potenial

Question 1

What is an action potential

Answer 1

Property of excitable cells that consists of a rapid depolarization or upstroke followed by repolarization of the membrane potential

Question 2

Define depolarization

Answer 2

Making a membrane potential less negative

Question 3

Define hyperpolarization

Answer 3

Making membrane potential more negative

Question 4

Define inward current

Answer 4

Flow of positive charges into the cell

Depolarizes membrane potential

Question 5

Define outward current

Answer 5

Flow of positive charges out of the cell

Hyperpolarizes membrane potential

Question 6

Define threshold

Answer 6

Membrane potential at which action potential is inevitable

Not inward current becomes larger than that outward current

Question 7

Describe the resting potential

Answer 7

-70 mV

Result of high resting conductance to k+ which drives the membrane potential towards the k+ equilibrium potential

Question 8

Describe the depolarization of the action potential

Answer 8

▪️Inward current of Na+ depolarizes the membrane potential to threshold
▪️Depolarization causes rapid opening activation gates of the NA+ channels and ▪️NA+ conductance of the membrane increases
▪️ equilibrium potential is +65 mV

Question 9

What is the inactivated state

Answer 9

When the sodium ion channels rapidly entered a closed state and remain in the state for a few milliseconds before returning to the resting state when they can again be activated

Question 10

How is Na+ influx limited

Answer 10

Direction of electrical gradient for Na+ positive is reversed during the overshoot because the membrane potential is reversed

Question 11

What is rapid depolarization caused by

Answer 11

Inward Na+ current

Question 12

Describe how repolarization of action potential occurs

Answer 12

Closure of NA channels take place in the Na conductance returns to zero