Electrical Activity of the Heart

Question 1

Angina Pectoris

Answer 1

A condition
marked by severe
pain in the chest,
often also
spreading to the
shoulders, arms,
and neck, caused
by an inadequate
blood supply to the
heart (ischemia).

Question 2

Ischemia affects…

Answer 2

Reduced Blood Flow
Limited ATP available

Question 2

The sinoatrial node is the
heart’s pacemaker
because it initiates each
wave of excitation known
as

Answer 2

depolarization

Question 3

A P wave is…

Answer 3

Atrial depolarization

Question 4

PR interval…

Answer 4

Time between onset of atrial depolarization and ventricular depolarization

Question 5

QRS complex…

Answer 5

Ventricular depolarization

Question 6

ST Segment…

Answer 6

Ventricles depolarized (plateau phase)

Question 7

T wave…

Answer 7

Ventricular repolarization

Question 8

QT interval…

Answer 8

represents the
time for both ventricular depolarization
and repolarization to occur, duration
ventricular action potential

Question 9

Ion distribution - where do we find more K?

Answer 9

Inside cell

Question 10

Ion distribution - where do we find more Na+?

Answer 10

Outside cell

Question 11

Resting Membrane
Potential [RMP] is
between

Answer 11

-60 and -90 millivolts.

Question 12

T/F - K+ is highly permeable

Answer 12

T

Question 13

What do Na+/K+ pumps in myocardial cell membranes do?

Answer 13

Pump 3 Na+ out and 2 K+ in

Question 14

Depolarization =

Answer 14

Excitation/contraction

Question 15

Repolarization =

Answer 15

Relaxation/return to rest

Question 16

Primary Problems of Ischemia

Answer 16

Reduced Blood Flow * Limited ATP Available * Failure of ATP Pumps * K+ Accumulates in Interstitial Fluid * Na+ Moves into Cells (voltage–gated channels) * Resting Membrane Potential Less Negative * Membrane Depolarized, unable to establish RMP