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Flashcards in 3.2 Cardiac Function Deck (70):
1

General parts of CV system

Blood, heart and vasculature

2

Which side of the heart is pulmonary?

Right

3

Which side of the heart is systemic?

Left

4

Which side of the heart has significant musculature?

Left

5

3 layers of cardiac histology
(inner to outer)

Endocardium
Myocardium (cardiac muscle)
Epicardium

6

Endothelial cells always...

Touch blood (In the endocardium)

7

Heart muscle cells (name)

Cardiomyocytes

8

What are the general features of cardiomyocytes similar to? (Z-discs, I/A bands, thin / thick filaments of myosin?

Skeletal muscle sarcomere

9

Why are cardiomyocytes similar to neurons?

They maintain a resting membrane potential

10

Two types of cardiomyocytes

Pacemaker (1%) and contractile cells (99%)

11

How do cardiomyocyes maintain negative membrane potentials?

Na / K+ Pumps
Pumping out Ca2+

12

How do cardiomyocytes pump out Ca2+?

Secondary active transport with Na+

13

Do pacemaker cells have a true RMP?

No but they bottom out at -60 mV

14

Do contractile cells have a true RMP?

Yes, -90mV

15

Mitochondria are what percent of cardiomyocytes?

25%

16

What are cardiomyocyes reliant upon?

Aerobic cellular respiration

17

What is coronary ischemia?

Essentially a heart attack, blockage of blood flow, cells die because they are so reliant on oxygen

18

What does hypoxia do? (depolarize / hyper polarize)

Depolarize, bring them more positive, away from RMP

19

Cardiac pacemaker and conductile tissue is..

Autorythmic

20

Does reaching threshold to cause an action potential in cardiomyocytes require neuronal action potentials or acetylcholine?

NO

21

What is normally the cardiac pacemaker?

SA node

22

Depolarization rate: location

SA node > AV node > Purkinje

23

If unmodified by ANS, what does the SA node set the heart rate as?

100 BPM

24

What happens if there is SA node damage?

AV node assumes (slower) pacemaker role which leads to Brachycardia

25

Ectopic foci

AKA ectopic pacemaker, other irritated of hypoxic tissue can cause premature contractions

26

Any region can become the pacemaker if...

It is the fastest to depolarize

27

What causes the gradual rise in RMP of pacemaker cells?

Na + leakage (until threshold) through slow voltage gated channels
Determines heart rate!

28

What rapid influx causes depolarization in pacemaker cells?

Influx of Ca+ through fast voltage gated Ca2+ channels

29

What outflow causes repolarization in pacemaker cells?

Outflow of K+ through voltage gated K+ channels

30

In order to increase heart rate, what would your body do?

Leak more sodium faster (sympathetic influence)

31

Do neurons leak sodium like pacemaker cells?

NO

32

Cardiomyocte cells are _____ coupled

Electrically

33

Cardiac mycoses share a "continuous" cytoplasm via...

Intercalated discs, leaky interconnections containing gap junctions (large pores) and desmosomes ( strong cell-cell ties or anchors)

34

Why are cardiomyocytes electrically coupled?

Creates a synctium where electrical depolarization spreads between cells

35

What connects every cell in heart? (notes)

Gap junctions

36

What keeps cells physically connected to each other? (notes)

Intercalated disks

37

What are found within intercalated disks? (notes)

Gap junctions and desmosomes

38

What must the depolarizing current travel through to reach the ventricles?

AV node (delays impulse)

39

What occurs during the depolarization phase of contractile cardiomyocytes?

Na+ influx through fast Na+ voltage gated channels

40

What occurs during the plateau phase of contractile cardiomyocytes?

-Voltage gated K+ channels open and K+ flows out
-Slow voltage gated Ca2+ channels open (prolonging depolarization)

41

What occurs during the repolarization phase of contractile cardiomyoctes?

Voltage gated Ca2+ channels close, voltage gated K+ channels remain open, potassium flows out of the cell

42

What is the function of the plateau?

Prevents tetany and is a potent signal for contraction of sarcomere

43

What cells does an EKG measure?

Contractile cardiomyocytes

44

Why can't you see atrial repolarization?

"Buried" by depolarization occurring in ventricles

45

What is an EKG?

Myocardial electrical currents detected on skin

46

What occurs during the p-wave?

Atrial depolarization

47

What occurs during the QRS complex?

Ventricular depolarization

48

What occurs during the T-wave?

Ventricular repolarization

49

Ventricular systole

Ventricles are contracting and emptying blood to arteries

50

Ventricular Diastole

Ventricles are relaxed and then filled by the atria

51

What interval is systole?

Q-T interval

52

When on the EKG does diastole occur?

End of T to beginning of next Q

53

What would an enlarged P or R wave be indicative of?

Atrial or ventricular hypertrophy

54

What would a larger Q wave or flattened T wave mean?

Myocardial infarction

55

What would elongation of the P-Q interval indicate?

Scarring from coronary artery disease

56

What would an S-T interval raised above baseline indicate?

Scarring from coronary artery disease

57

What would an elongated Q-T interval indicate?

Oxygen deprived ventricles

58

What is cardiac output?

Volume of blood pumped per minute

59

Equation of cardiac output

CO = Heart Rate x Stroke Volume

60

HR =

Beats / minure

61

Stroke volume =

Volume of blood ejected / beat OR (EDV - ESV)

62

End diastolic volume

The amount of blood into the relaxed volume

63

End systolic volume

Amount of blood left in heart after contraction

64

Chronotropic agents

Affect heart rate
(sympathetic nervous system)
Alter SA and AV node

65

Inotropic agents

Affect stroke volume
Alter Ca2+ levels in sarcoplasm

66

Brainstem Cardiovascular Center and the Autonomic Nervous system

Based on peripheral inputs to the brainstem CV center

67

Sympathetic influence on the heart

Cardiac accelerator nerves release norepinephrine to increase HR and ventricular contractility

68

Parasympathetic influence on the heart

Vagus nerves release acetylcholine to decrease HR and ventricular contractility

69

How does epinephrine and norepinephrine create a stronger contraction (and increase stroke volume)?

Increases Ca influx into cardiomyocytes

70

What do thyroid hormones do?

Increase heart rate and contractility