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Physiology 150 > Unit 6 - Cardiac Physiology > Flashcards

Unit 6 - Cardiac Physiology Flashcards

1
Q

Heart is composed of what three components?

A

Arteries, Veins, Septum

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2
Q

Arteries

A

carry blood away from the ventricles to tissues

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3
Q

Veins

A

Vessels that return blood from tissues to the atria

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4
Q

Septum

A

continuous muscular partition that prevents mixture of blood from the two sides of heart

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5
Q

Blood flow though heart

A

Inferior/superior vena cava, right atrium, right AV valve (tricuspid), right ventricle, pulmonary valve, pulmonary artery, lungs, pulmonary veins, left atrium, left AV valve (micuspid), left centricle, aortic valve, aorta.

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6
Q

Three things pulmonary circulation does (R heart)

A
  1. Circuit of vessels carrying blood between heart and lungs
  2. lungs add O2 and remove CO2
  3. flows through pulmonary veins to LA
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7
Q

Two things Systemic circulation does (L heart)

A
  1. circuit of vessels carrying blood between heart and body systems
  2. oxygen rich blood pumped from LA to LV to body through aorta
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8
Q

What side of the heart has oxygen rich blood?

A

left side

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9
Q

What side of the heart has de-oxygenated blood?

A

right side

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10
Q

Coronary Circulation

A

Coronary arteries on outside of heart and come from aorta. Per fused from aorta during diastole.

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11
Q

Right coronary artery supplies blood to

A

right side of heart

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12
Q

Left coronary artery supplies blood to

A

left side of heart

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13
Q

AV valves

A

R & L valves are positioned b/w atria and ventricles to prevent back-flow of blood from ventricles into atria during ventricular emptying

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14
Q

Right AV valve

A

tricuspid valve

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15
Q

Left AV valve

A

bicuspid valve

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16
Q

Chordae tendinae

A

fibrous cords prevent valves from being everted and papillary muscles

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17
Q

Heart valves pressure

A

atrial pressures not much higher than venous pressures

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18
Q

What is partially compressed during atrial contraction

A

superior, inferior venae cavae and pulmonary vein

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19
Q

Three things semi-lunar valves do

A
  1. aortic and pulmonary valves
  2. lie at juncture where major arteries leave ventricles
  3. prevented from everting by anatomic structure and positioning of cusps
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20
Q

Electrical Activity of Heart

A

heart beats rhythmically as result of action potentials it generates by itself

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21
Q

two specialized types of cardiac muscle cells

A
  1. contractile cells

2. auto rhythmic cells (pacemaker cells)

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22
Q

Contractile cells

A

99% of cardiac muscle cells. Contract-do mechanical work pumping. RMP is -80 mV with threshold of -40 mV

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23
Q

Autorhythmic cells

A

1% of cardiac muscle cells. Initiate & conduct action potentials that result in contraction of working cells. Do not contract no RMP

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24
Q

4 locations of pacemaker cells

A
  1. SA node
  2. AV node
  3. Bundle of His
  4. Purkinje fibers
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25
Q

Sinoatrial Node

A
  1. Specialized region in R atrial wall near opening of superior vena cava
  2. PACE MAKER OF THE HEART 60-100 time/min
  3. AP spreads throughout right and left atria
  4. impulse passes from atria into centricles though AV node (only point of electrical contact between chambers)
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26
Q

Atrioventricular Node

A
  1. Small bundle of specialized cardiac cells located at base of RA near septum
  2. slows impulse conduction between atria and ventricles, allowing atria to fill with blood before ventricles contract
  3. impulse then travels to bundle of his
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27
Q

Bundle of His

A

Divides to for R and L bundle branches

AP travels down septum, curve around tip of ventricular chambers, travel back toward atria along outer walls

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28
Q

Purkinje fibers

A
  1. small terminal located at distal portions of both bundles
  2. impulse travels through myocardium
  3. ventricular cells activated by cell to cell spread of impulse
  4. ventricles then contract
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29
Q

Back-up System

A
  1. SA node (60-100 beats/min)
  2. AV node (40-60 beats/min)
  3. Bundle of His & Purkinje Fibres (20-40 beats/min)
  4. Ectopic focus
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30
Q

ECG waveforms

A

PQRSTP

31
Q

P wave

A

atrial depolarization

32
Q

PR segment

A

AV nodal delay

33
Q

QRS complex

A

ventricular depolarization (atria repolarizing simultaneously)

34
Q

ST segment

A

time during which ventricles are contracting and emptying

35
Q

T wave

A

Ventricular repolarization

36
Q

TP interval

A

time during which ventricles are relaxing and fillin

37
Q

Cardiac cycle

A

beginning of one heart beat to beginning of next

38
Q

Two phases of cardiac cycle

A

systole and diastole

39
Q

systole

A

contraction and emptying

40
Q

diastole

A

relaxation and filling

41
Q

Ventricular diastole (relaxation)

A
  1. mid ventricular diastole

2. late ventricular diastole

42
Q

Mid ventricular diastole

A

atria in diastole (TP) and atrial filling

43
Q

Late ventricular diastole

A

SA node reaches threshold (P)

atrial pressure >ventricular pressure -> AV valves open and 50-90% of blood fills ventricles

44
Q

Late ventricular diastole (atrial systole)

A

atrial contraction and last 10-25% of blood emptied into ventricle (atrial kick)

45
Q

End of ventricular diastole

A

ventricular filling complete. end diastole volume 135ml. max volume of blood that ventricle contains just before systole

46
Q

Ventricular systole (contraction)

A

heart contracting

47
Q

onset of ventricular systole

A

impulse at AV node (starts QRS) and ventricular pressure begins to rise

48
Q

Isovolumetric ventricular contraction

A

brief period before semilunar valves are open.
ventricular pressure > atrial pressure -> AV valves shut.
ventricle is closed chamber

49
Q

Ventricular pressure rises

A

semilunar valves opened and ejection of blood begins

50
Q

Stroke volume

A

amount of blood pumped out of each ventricle with each contraction (70ml)

51
Q

End of ventricular systole

A

only pumps out 50% of blood. blood left in ventricle is end systolic volume (ESV 65ml)

52
Q

Ventricular Diastole (Relaxation)

A

repolarization of ventricles (T wave)

53
Q

Repolarization of ventricles (T wave)

A

ventricular pressure drops below aortic/pulmonic pressure -> semilunar valves close

54
Q

isovolumetric ventricular relaxation

A

briefly, ventricular pressure exceeds atrial pressure
AV closed and no blood from atrium.
All valves closed

55
Q

atrial pressure > ventricular pressure

A

AV valve opens, ventricles filled and cardiac cycle begins again

56
Q

Heart sounds

A

Two major sounds
1st low pitched and soft lub (closure of AV valves during systole)
2nd has a higher pitch dup (closure of the semilunar valves during diastole)

57
Q

S1 -> S2

A

Diastole

58
Q

S2 -> S1

A

Systole

59
Q

Cardiac output

A

blood volume ejected each minute from LV into aorta and from RV to pulmonary artery
HR x SV

60
Q

Heart Rate

A

varied by altering balance of parasympathetic and sympathetic influence on SA node

61
Q

Parasympathetic stimulation

A

CN X (Vagus)
SLows down SA node to reduce heart rate
Decreases the AV nodes excitability
Weakens atrial contraction but little effect on ventricular contraction

62
Q

Sympathetic stimulation

A

increases heart rate speeding up SA node depolarization
Reduces AV nodal delay and speeds up spread of action potential
increases force of contraction

63
Q

Stroke Volume

A

amount of blood pumped out of each ventricle with each contraction

64
Q

SV calculation

A

EDN - ESV

70ml apx

65
Q

Stroke volume is influenced by

A

intrinsic control and extrinsic control

66
Q

intrinsic control

A

EDV
venous return
strength of cardiac contraction

67
Q

Extrinsic control

A

sympathetic activity

increased strength of contraction

68
Q

Frank-Starling Law of the Heart

A

Relationshop b/w EDV and stroke volume
Heart normally pumps out during systole the volume of blood returned to it during diastole
the high EDN the higher SV
The more the fibres stretch, the more forcefully the ventricles contract during systole

69
Q

Preload

A

the greater the volume of blood into ventricles, the greater the heart muscle is stretched during diastole and the greater the force of contraction.
“Filling”

70
Q

Contractility

A

ability of myocardium to contract

influenced by preload (greater the stretch -> the more forceful the contraction)

71
Q

Afterload

A

pressure required for ventricular muscles to overcome resistance in P & A valves to pump blood out of heart

72
Q

Factors affecting HR

A

autonomic innervation
hormones
fitness levels
age

73
Q

factors affecting SV

A 
heart size
fitness levels
gender
contractility
duration of contraction
Preload (EDV)
Afterload (Resistance)

Physiology 150 (11 decks)

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