Heart

Question 1

Gap Junctions - def, effect on AP speed

Answer 1

Low resistance electrical connections between cells, fewer gap junction increase longitudinal resistance, decreasing speed.

Question 2

Desmosomes - def

Answer 2

Mechanical adhering Junctions

Question 3

SA node - location, fxn

Answer 3

Right Atrium
Initiate AP
Sets HR

Question 4

Ventricular AP - triggered by

Answer 4

Ca2+ that enters myoplasm

Question 5

P wave

Answer 5

Upstroke of AP across atria

Question 6

QRS complex

Answer 6

Upstroke of AP across ventricles

Question 7

T wave

Answer 7

ventricular repolarization

Question 8

interval btwn end of P and Start of Q

Answer 8

AV nodal delay

Question 9

ST segment

Answer 9

plateau of ventricular action potential

Question 10

Isovolumetric contraction

Answer 10

chambers closed during conraction

i.e. when pLV>pLA but pLV< pAorta; mitral closes, and aortic stays closed until pLV>pAorta

Question 11

Average ejection fraction

Answer 11

60%

Question 12

Isovolumetric relaxation

Answer 12

chambers closed during relaxation

i.e. when pLVpLA. aortic valve close and mitral stays closed until pLV<pLA

Question 13

Consequences of no ATP in heart

Answer 13

K+ inc. extracellular (Na/K pump not working)
Gradient lost
Resting potential less negative (towards 0)
AP not possible
MYOCARDIAL INFARCTION

Question 14

Contractile AP v AP of SA and AV nodes

Answer 14

Fast response AP (fast upstroke) v Slow response action AP (slow upstroke)