Electrical Activity of the Heart

Question 1

What is the —Ability of the heart to conduct its own AP (without input from NS) across its membrane which leads to contraction of the muscle and ejection of blood out of ventricles

Answer 1

—Autorythmicity

Question 2

Autorhythmic Locations of the Heart

Answer 2

—Sinus atrial node (SA node)

—AV node (junction between atria and ventricles) —

L and R Bundle of His —

Purkinje fibers (not the same as Purkinje cells of the NS!)

Question 3

—Each autorythmic location has a different _________ so they generate APs at different rates

Answer 3

threshold

Question 4

What is the native pacemaker of the heart?

Answer 4

SA Node

Question 5

What is —Located in the right atrium; lowest threshold

Answer 5

SA Node

Question 6

What —Normally begins the conduction pathway

Answer 6

SA Node

Question 7

—The SA Node performs “___________” = suppresses the other locations from generating Aps

Answer 7

overdrive suppression

Question 8

—These locations _______________ receive AP from SA node before they have had time to reach threshold by themselves

Answer 8

AV Node, Bundle of His

Question 9

—if SA node fails to elicit AP for a certain period of time, ________ assumes pacemaker activity

Answer 9

AV Node

Question 10

What is the —“latent pacemaker”?

Answer 10

AV Node

Question 11

—AV Node contraction will be at a lower rate because takes longer to reach __________ than at SA node

Answer 11

threshold

Question 12

—A complete heart/AV block = —Communication between ______________ completely blocked, no messages being passed along

Answer 12

atria and ventricles

Question 13

—A complete heart/AV block = —SA node and AV node conducting at normal pace and atria contracting normally, but ________ not getting the message

Answer 13

ventricles

Question 14

—If Bundle of His and Purkinje fibers do not receive anything from atria –> start their own ______ –> slower than if receiving AP from SA node

Answer 14

rhythm

Question 15

—Abnormally excitable area outside of the SA node that depolarizes much more rapidly than the SA node

Answer 15

Ectopic Focus

Question 16

—Ectopic Focus initiates its own premature AP which spreads through the heart before the normal AP from the _________.

Answer 16

SA Node

Question 17

Ectopic focus —Produces a premature beat or __________

Answer 17

extrasystole