Cardiac Electrophys (lec 1)

Question 1

Preload is?

Answer 1

stretch on vent at end diastole

Question 2

Afterload is?

Answer 2

pressure against which heart pumps

Question 3

2 types of heart cells?

Answer 3

myocardial

conducting

Question 4

SNS effects on heart? (4)

Answer 4

↑ SA node pace
↑ A/V node impulse conduction
↑ contraction force
coronary vasodilation
constriction of peripheral bv
= ↑  CO and BP

Question 5

PNS effects on heart?

Answer 5

(vagus n)
↓ SA node pace
↓ AV node conduction

Question 6

Properties of Myocardial cells? (4)

Answer 6

1) automaticity (produce impulse w/o outside stim
2) excitability (respond to stim)
3) conductivity (transmit impulse cell-to-cell)
4) contractility (contract when stimulated)

Question 7

Properties of Pacemaker cells?

Answer 7

spontaneous generation of impulse (depol)

Question 8

Properties of Conducting cells?

Answer 8

carry signal

Question 9

Sinoatrial Node?

Answer 9

pacemaker
in posterior R atrium
60-100 bpm

Question 10

Atrioventricular Node?

Answer 10

impulse pathway to vents
in low R atrium
40-60 bpm

Question 11

Properties of Purkinje Fibers?

Answer 11

terminal branches of R/L bundles
20-40 bpm
take over for SA/AV nodes if fail

Question 12

Polarized State is?

Answer 12

resting myo cells

- inside/+ outside

Question 13

Depolarized State?

Answer 13

Na+ and Ca2+ enter cell

create AP

Question 14

Repolarization?

Answer 14

Na+, Ca2+, K+ leave cell

Question 15

Absolute Refractory Period?

Answer 15

temp resistant to depol
keeps depol wave moving forward
prevents spasm (continued contraction)

Question 16

Relative Refractory Period?

Answer 16

in late repol, very strong signal can cause depol

Question 17

Bipolar Leads?

Answer 17

+ and -

limb leads

Question 18

Unipolar Leads?

Answer 18

+ only
chest/precordial
augmented limb

Question 19

Upright Vectors?

Answer 19

show movement toward + electrode

Question 20

Downward Vectors?

Answer 20

show movement away from +/towards - electrode

Question 21

Biphasic Vectors (up and down)?

Answer 21

impulse perpendicular to + electrode

Question 22

P Wave?

Answer 22

atrial depol

Question 23

QRS Complex?

Answer 23

vent depol

Question 24

T Wave?

Answer 24

vent repol

Question 25

Atrial Repol where?

Answer 25

hidden in QRS