Karius: Cardiac Cycle and Normal ECG ibook notes Flashcards Preview

Cardiopulmonary Exam 1 > Karius: Cardiac Cycle and Normal ECG ibook notes > Flashcards

Flashcards in Karius: Cardiac Cycle and Normal ECG ibook notes Deck (61):
1

Fast action potentials are found where

atrial and ventricular

2

Slow action potentials are found

in the SA and AV nodes

3

Fast action potential phase 0:

rapid upsweep (depolarization)

voltage gated Na channels open and the cell is rapidly depolarizing

same as skeletal muscle

4

Fast action potential phase 1:

occurs around +20 mV

Initial repolarization

sodium channels inactivate so no more sodium enters; voltage gated potassium channels open

5

Fast action potential phase 2:

plateau

"slow voltage gated calcium channels opening" AND "special voltage gated K channels closing"

6

Fast action potential phase 3:

Repolarization, Slow Ca channels closing and special K channels opening

7

Fast action potential phase 4:

resting potential sustained by high potassium conductance

around -85 mV

8

SA node and AV node AP: phase 4

resting membrane potential is NOT isotonic, gradually increases (depolarizes) until threshold value achieved and SA first; this is due to the funny Na voltage gated channels. (Na channels open during repolarization)

this is an intrinsic spontaneous event

AV node has same thing but phase 4 is much slower, normally doesnt reach threshhold value before being stimulated by an action potential originating in the SA node

9

SA node and AV node AP: phase 0

due to opening of slow Ca gates and closing of special K gates

same for AV node

10

SA node and AV node AP: phase 3

remember: no 1 or 2 phase, goes from 0 to 3

11

Normal EKG: P wave

atrial contraction

12

Normal EKG: QRS wave

ventricular contraction

13

Normal EKG: T wave

ventricular repolarization

14

PR interval

starts at beginning of P wave and ends at beginning of QRS complex

AV nodal delay time.

represents time it takes to pass from atria to the ventricles via the AV node: this is incorrect I believe

15

ST wave

begins at end of QRS, ends at beginning of T

16

QR interval:

begins with beginning of the QRS complex and ends at the end of the T wave, so it includes two waves

QRS and T wave

represents total time any ventricular myocite is depolarized

17

beginning of P wave and the cardiac cycle

both atria and ventricles are in diastole
all voltage gated channels are closed except for leaky K and Na/K ATPase

SA and AV nodes in P4, with funny Na channels operating (pre-potential)

AV has fewer funny channels so its pre-potential is slower to develop

Tricuspid and Bicuspid are open

Aortic and pulmonic are closed

18

pressure of left and right atrium during diastole

diastolic mmHG is usually 4 mmHg

19

pressure in left and right ventricles during diastole

0 mmHg

pressure in ventricle must be less than in atria for blood to flow

20

Pulmonary artery pressure diastole

15 mmHg

21

Aorta pressure diastole

80 mmHg

22

how will diastole pressure be effected if resistance in the arteries is high?

diastolic pressure will be higher

23

how will diastole pressure be effected if resistance in the arteries is low?

diastolic pressure will be lower

24

Jugular Vein: why is this sensitive to blood flow changes?

there are no valves between the atria and the veins

changes in atria; pressure will effect venous return

25

Atrial contraction: wave, pressure direction, direction of blood, and ventricular pressure

P wave
from atria into ventricles
ventricular pressure increases as well

26

Why doesnt the ventricle contract before the atria?

the AV has a slow ventricular depolarization to allow for blood to fill

27

What is the normal pressure of the ventricles at their height of contraction?

around 120 mmHg, on the left side

28

During the ___ wave the left ventricular pressure begins to increase.

P wave

29

During the QR phase, the left ventricle pressure

decreases for a moment and then increases,

30

the mitral valves open at _____ wave

the pinnacle of the R wave

31

Left ventricular pressure goes _______ during RS phase

WAY up, very steep increase: the aortic valve is closed during this period, hence the pressure build up

32

the ST line corresponds roughly with the ventricular pressure diagram. What is the character of the pressure?

pressure increases in the left ventricle from the pinnacle of the R wave to the very beginning of the T wave. it increases just a bit more and then decreases mostly during the T wave

33

the aortic valves close near the ____ point on the EKG

right after the T wave (repolarization)

34

the mitral valve opens during what part of the EKG?

inbetween the T and P waves (during the isoelectrical period)

35

The first heart sound (S1) occurs immediately

after the AV valves close: blood suddenly hits the closed valve/cardiac structure (now closed) making the first "lub" sound

S1 is the loudest sound

36

What waves are you going to count to determine the net deflection in the limb leads?

QRS

37

What waves are you going to count to determine the net deflection in the limb leads?

QRS

38

What waves are you going to count to determine the net deflection in the limb leads?

QRS

39

Inferior leads =

II, III, AVF

40

What waves are you going to count to determine the net deflection in the limb leads?

QRS

41

Inferior leads =

II, III, AVF

42

What waves are you going to count to determine the net deflection in the limb leads?

QRS

43

Inferior leads =

II, III, AVF

44

What waves are you going to count to determine the net deflection in the limb leads?

QRS

45

Inferior leads =

II, III, AVF

46

What waves are you going to count to determine the net deflection in the limb leads?

QRS

47

Inferior leads =

II, III, AVF

48

what does the PR interval indicate?

no voltage difference between the atria

49

what direction does the SA node depolarize the atria?

Right to Left

50

segment refers to

a single event on an ECG

51

interval refers to

several events on an ECG

52

In what phase of an atrial or ventricular action potential do you find the voltage gated potassium channels, and what kind of voltage opens them?

phase 1: they open during depolarization

53

In what phase of an atrial or ventricular action potential do you find the timed gated potassium channels, and what kind of voltage opens them?

phase 3
stays closed during phase 2 and then helps open during phase 3.

the T wave represents depolarization of ventricular myocytes

the timed gated potassium channels are found during the 2nd phase and they are voltage gated, but they close during depolarization, and stay closed for a finite amount of time

54

what phase on the ECG is represented by phase 0?

P wave and QRS respectively

55

PR segment vs PR interval

PR interval represents the beginning of P wave until beginning of QRS: how long does the signal take to geth through the AV node

PR segment represents the end of atrial depolarization until beginning of QRS-

56

QT interval is largely controlled by what gates?

timed potassium gates

57

what is responsible for controllign plateau phase?

closing of potassium gates and opening of calcium gates

58

Inferior leads =

II, III, AVF, R. coronary artery

59

septal regions =

V2 and V3

60

anterior region of the heart region =

V2, V3, V4

61

Lateral heart

I, AVL, V4,V5, V6