Dr. Najeeb Lecture 1 - Electrophysiology

Question 1

Myocardial cells

Which ions are contained:

intracellular vs extracellular?

Answer 1

Intracellular: K+

Extracellular: Na+

Question 2

Depolarization -
Direction & Amount of Ions:

Which go in?

Which go out?

Answer 2

2 Na+ go in

3 K+ go out

Question 3

Depolarization-

What charge is produced?

Answer 3

-5 mV

Question 4

Na+ levels intracellularly vs extracellularly

Answer 4

Na+

Intracell: Low
Extracell: High

Question 5

K+ levels intracellularly vs extracellularly

Answer 5

Intracell: High
Extra: Low

Question 6

Which ion has a leaky channel?

Answer 6

K+ has leaky channels

Question 7

What is the RMP?

Answer 7

-90 mV

Question 8

Resting myocyte - charge intracellularly vs extracellulary?

Answer 8

Intracell: Negative
Extracell: Positive

Question 9

Depolarization:
How does it begin?

Answer 9

Na+ cations enter cell & increase membrane potential

Question 10

Depolarization:

What threshold (mV) is needed to be reached?

What happens when reached?

Answer 10

-70mV

Na+ activation gates open quickly

VG-Na+ inactivation channels close slowly

Question 11

Depolarization:

As Na+ cations enter into cell, at what threshold (mV) do inactivation gates close?

Answer 11

10 mV

Question 12

Gap Junctions:

Function during depolarization

Answer 12

“Windows” between myocardial cells, allow electrical impulses to pass