Cardiac excitability/electro

Question 1

Cardiac action potential has 5 phases

Answer 1

0-4

Question 2

cardiac action potential phase 0

Answer 2

membrane potential -> threshold

• voltage gated Na channels open -> influx
• depolarization: upstroke

Question 3

cardiac action potential phase 1

Answer 3

small repolarization: closure of Na channels

transient efflux of K+

Question 4

cardiac action potential phase 2

Answer 4

plateau phase

- Ca influx offset by K+ efflux

Question 5

cardiac action potential phase 3

Answer 5

rapid return to resting potential

• closure of Ca channels
• K efflux

Question 6

cardiac action potential phase 4

Answer 6

period of time between AP no change in membrane voltage

Question 7

SA node

Answer 7

pacemaker: 60-80 BPM
origin of impulse
upper Right ventricle

Question 8

AV node

Answer 8

spontaneous depolarization: 40-60 BPM

bottom of Right Atria, just above R. ventricle

Question 9

Purkinje fibers

Answer 9

spontaneous depolarization: 15-40 BPM

innervate muscle around ventricles

Question 10

bundle branches

Answer 10

between AV node and purkinje fibers go down interventricular septum

Question 11

overdrive suppression

Answer 11

faster pacemakers suppress automatic discharge of slower pacemakers

Question 12

P wave

Answer 12

atrial depolarization

Question 13

QRS

Answer 13

ventricular depolarization

Question 14

T wave

Answer 14

Ventricular repolarizatoin

Question 15

S

Answer 15

depolarization of ventricular base

Question 16

Q

Answer 16

septal depolarization