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DMD 5247 > Cardiovascular Physiology > Flashcards

Cardiovascular Physiology Flashcards

1
Q

heartbeat

A

a single contraction of the heart

the entire heart contracts in series

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2
Q

order of contraction within the heart

A

first atria, then ventricles

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3
Q

2 types of cardiac muscle cells

A

conducting system

contractile cells

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4
Q

conducting system

A

controls and coordinates the heartbeat

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5
Q

contractile cells

A

produce contractions that propel blood

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6
Q

what begins the cardiac cycle

A

an action potential at the SA node

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7
Q

what happens after the production of an action potential at the SA node

A

transmitted through conducting system

produces action potentials in cardiac muscle cells(contractile cells)

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8
Q

electrocardiogram

A

electrical events in the cardiac cycle can be recorded on an electrocardiogram

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9
Q

the conducting system

A

a system of specialized cardiac muscle cells

  • initiates and distributes electrical impulses that stimulate contraction
  • automaticity: cardiac muscle tissue contracts automatically
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10
Q

contractile cells

A
  • purkinje fibers distribute the stimulus to the contractile cells, which make up most of the muscle cells in the heart
  • resting potential: of a ventricular cell: -90 mV
  • of an atrial cell about -80 mV
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11
Q

conduction system ion channels

A

potassium, sodium, calcium

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12
Q

myocardium ion channels

A

potassium, sodium, calcium

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13
Q

blood vessels ion channels

A

calcium, potassium, chlorine

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14
Q

action potential in cardiac muscle

A
  • rapid depolarization
  • plateau
  • repolarization
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15
Q

rapid depolarization

A

caused by sodium entry and ends with closure of voltage-gated fast sodium channes

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16
Q

the plateau

A

caused by calcium entry and ends with closure of the slow calcium channels

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17
Q

repolarization

A

caused by potassium loss and ends with closure of slow potassium channels

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18
Q

absolute refractory period

A

long

cardiac muscle cells cannot respond

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19
Q

relative refractory period

A

short and response depends on degree of stimulus

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20
Q

purpose of the long refractory period in cardiac cells

A

prevent summation and tetany

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21
Q

contraction of a cardiac muscle cell is caused by

A

an increase in calcium ion concentration around myofibrils

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22
Q

the role of calcium ions in cardiac contractions

A

calcium ions enter plasma membrane during the plateau phase

this triggers release of calcium ion reserves from sarcoplasmic reticulum

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23
Q

as slow calcium channels close

A

intracellular calcium is absorbed by the SR
or pumped out of the cell

cardiac muscle tissue is very sensitive to extracellular Ca concentrations

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24
Q

structures of the conducting system

A

sinoatrial node
atrioventricular node
conducting cells: throughout myocardium

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25
Q

conducting cells in the atrium

A

present in internodal pathways

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26
Q

conducting cells in the ventricles

A

present in the AV bundle and bundle branches

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27
Q

Prepotential

A

pacemaker potential
resting potential of conducting cells
-gradually depolarizes toward threshold

SA node depolarizes first, establishing the heart rate

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28
Q

the sinoatrial node

A
  • in posterior wall of right atrium
  • caontains pacemaker cells
  • connected to AV node by internodal pathways
  • begins atrial activation
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29
Q

AV bundle

A
  • in the septum
  • carries the impulse to the left and the right bundle branches
  • which conduct to purkinje fibers
  • and to the moderator band
  • which conducts to papillary muscles
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30
Q

purkinje fibers

A

distribute the impulse through the ventricles
atrial contraction is completed
ventricular contraction begins

31
Q

abnormal pacemaker function

A

bradycardia
thachycardia
ectopic pacemaker

32
Q

ectopic pacemaker

A

abnormal cells
generate high rate of action potentials
bypass conducting system
disrupt ventricular contractions

33
Q

P wave

A

atria depolarize

34
Q

QRS complex

A

ventricles depolarize

35
Q

T wave

A

ventricles repolarize

36
Q

P-R interval

A

from the start of atrial depolarization to the start of a QRS complex

37
Q

Q-T interval

A

from ventricular depolarization

to ventricular repolarization

38
Q

the cardiac cycle

A

is the period between the start of one heartbeat and the beginning of the next
includes both contraction and relaxation

39
Q

2 phases of the cardiac cycle

A

systole: contraction
diastole: relaxation
* each is within any one chamber

40
Q

atrial systole

A

atrial contraction begins
right and left AV valves are open
atria eject blood into ventricles

41
Q

atrial systole ends

A

AV valves close
ventricles contain maximum blood volume
known as end-diastolic volume

42
Q

ventricular systole

A

ventricles contract and build pressure: AV valves close and cause isovolumetric contraction

43
Q

ventricular ejection

A

ventricular pressure exceeds vessel pressure opening the semilunar valves and allowing blood to leave the ventricle
amount of blood ejected is called the stroke volume

44
Q

ventricular pressure falls

A

semilunar valves close

ventricles contains end-systolic volume: about 40% of end diastolic volume

45
Q

ventricular diastole

A

ventricular pressure is higher than atrial pressure
all heart valves are closed
ventricles relax: isovolumetric relaxation

46
Q

atrial pressure is higher than ventricular pressure

A

AV valves open
passive atrial filling????
passive ventricular filling

47
Q

blood pressure in any chamber

A

rises during systole

falls during diastole

48
Q

blood flows from high to low pressure

A

controlled by the timing of the contractions

directed by one-way valves

49
Q

when heart rate increases

A

all phases of the cardiac cycle shorten, particularly diastole

50
Q

S1: heart sound

A

loud sounds

produced by AV valves

51
Q

S2: heart sound

A

loud sounds

produced by semilunar valves

52
Q

S3 and S4 sounds

A

soft sounds

blood flow into ventricles and atrial contraction

53
Q

heart murmur

A

sounds produced by regurgitation through valves

54
Q

cardiodynamics

A

the movement and force generated by cardiac contractions

55
Q

stroke volume

A

EDV-ESV = -SV

56
Q

ejection fraction

A

the percentage of EDV represented by SV

57
Q

cardiac output

A

the volume pumped by left ventricle in 1 minute

CO = HR * SV

58
Q

factors affecting cardiac output

A
  • changes in heart rate or stroke volume
  • heart rate is adjusted by the autonomic nervous system or hormones
  • stroke volume can be adjusted by changing the EDV or ESV
59
Q

autonomic innervation

A
  • cardiac plexuses innervate heart
  • vagus nerves carry parasympathetic preganglionic fibers to small ganglia in cardiac plexus
  • cardiac centers of the medulla oblongata
60
Q

cardiac centers of medulla oblongata

A
  • cardioaccelatory center: controls sympathetic neurons: increases heart rate
  • cardioinhibitory center: controls parasympathetic neurons: slows hart rate
61
Q

cholinergic receptors

A

activated by parasympathetic
M2 muscarinic receptors are mainly in the SA node
M2 activation: reduces heart rate: negative chronotropic

62
Q

adrenergic receptors

A

activated by sympathetic
B1 adrenergic receptors int he myocardium, SA node
B1 activation: increases contractility(positive inotropic)
: increased heart rate(positive chronotropic)

63
Q

angiotensin

A

AT1 Myocardium: positive inotropy

64
Q

membrane potential of the pacemaker cells

A

lower than other cardiac cells

65
Q

rate of spontaneous depolarization depends on:

A

resting membrane potential

rate of depolarization

66
Q

sympathetic and parasympathetic stimulation

A

greatest at the SA node

67
Q

Acetylcholine

A

parasympathetic

slows heart

68
Q

norepinephrine

A

sympathetic

speeds the heart

69
Q

atrial reflex

A

adjusts rate rate in response to venous return
stretch receptors in the right atrium
-trigger an increase in heart rate
-through increased sympathetic activity

70
Q

the frank-starling principle

A

as EDV increases, stroke volume increases

71
Q

afterload

A

caused by any factor that resists arterial blood flow

72
Q

afterload increases

A

stroke volume decreases

73
Q

preload

A

degree of ventricular stretching during ventricular diastole

DMD 5247 (13 decks)

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