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Cardiovascular Physiology > Cardiovascular Physiology > Flashcards

Cardiovascular Physiology Flashcards

1
Q

what is cardiac output

A

amount of blood pumped by each ventricle in one minute

-normal adult blood volume: 5 liters

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2
Q

how often does blood volume pass through the heart

A

once every minute

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3
Q

cardiac cycle

A

events that occur during one heart beat

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4
Q

ventricular systole

A

contraction/ejection

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5
Q

diastole

A

relaxation/filling

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6
Q

what is the normal heart rate

A

72 beats/min

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7
Q

heart general facts

A

250-250 grams

  • pyramidal shaped
  • lies in pericardium in mediastinum
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8
Q

what are the heart surfaces

A

3 surfaces

  • anterior (sternocostal surface): formed by right atria and right ventricle
  • inferior (diaphragmatic surface): formed by R & L ventricles separated by inter ventricular groove, also surface of right atrium where IVC opens
  • base of heart (posterior surface): formed by left atrium
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9
Q

where does the heart rest

A

in the diaphragmatic surface

does NOT rest on its BASE

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10
Q

mediastinum

A

contains all heart and thoracic viscera except the lungs

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11
Q

anterior mediastinum

A

thymus, fat, lymphatics

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12
Q

posterior mediastinum

A

descending aorta, esophagus, azygous veins, autonomics, thoracic ducts

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13
Q

middle mediastinum

A

heart, pericardium, aorta, trachea, main bronchi, lymph nodes

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14
Q

superior mediastinum

A

above sternal angle, aortic arch

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15
Q

inferior mediastinum

A

contains anterior, middle and posterior mediastinum

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16
Q

what does the pulmonary circuit consist of

A
  • right side of the heart
  • pumps blood to the lungs
  • CO2 unloaded, O2 picked up
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17
Q

what does the systemic circuit consist of

A
  • left side of heart

- pumps blood to the tissues, delivering O2 and picking up CO2 and wastes

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18
Q

where is the base of the heart directed towards

A

toward the right shoulder

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19
Q

where is the apex of the heart directed toward

A

the left hip

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20
Q

what is the heart inclosed in

A

pericardium sac

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21
Q

deep to the pericardium is what

A

the serous pericardium

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22
Q

what lies the inside of the pericardium

A

the parietal pericardium

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23
Q

what covers the surface of the heart

A

the visceral pericardium

aka epicardium

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24
Q

functions of the fibers skeleton

A
  1. valve support structure
  2. prevent over-stretching of valves
  3. electrical isolation b/w atria and ventricles
  4. cardiac muscles anchored to fibrous ring
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25
Q

cardiac muscle details

A
  • self contracting and auto regulated
  • y shaped
  • shorter and wider than skeletal muscle
  • predominantely mononucleated
  • posses many many mitochondria and myoglobin
  • ATP mostly aerobic
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26
Q

some of the cardiac muscles are auto rhythmic. what does that mean?

A

that they contract even w/o neurological innervation such as from pacemaker cells

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27
Q

what are intercalated discs?

A

located b/w cardiac muscle cells

  • allows cardia muscles to contract and work as pump
  • contain gap junction and desmosomes
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28
Q

what do gap junctions help

A

forms channels b/w adjacent cardiac muscle fibers that allow depolarizing current to flow form one cardiac muscle to the next
-allows quick transmission of action potential

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29
Q

what do desmosomes help?

A

anchors the end of cardiac muscle fibers together

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30
Q

how fast does cardiac muscles repolarize and how does that help cardiac muscles?

A
  • repolarization takes much longer to occur

- are not able to go into tetanus (sustained contraction)

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31
Q

sarcolemma

A

membrane around striated muscle cells

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32
Q

intercalated disc

A

connect cardiac myocytes together

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33
Q

gap junction

A

facilitate electrical activity to spread to adjacent cells

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34
Q

T-tubules

A

invaginate the sarcolemma

-allow impulses to penetrate the cell and activate the sarcoplasmic reticulum

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35
Q

sarcoplasmic reticulum

A

releases calcium ions during muscle contraction and absorb during relaxation

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36
Q

what supplies blood to the heart

A 
ivc
svc
coronary sinus
pulmonary veins
thebesian veins
bronchial veins
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37
Q

what do the bronchial veins drain into

A
  • pulmonary veins or left atrium

- into azygous vein (right) or superior intercostal vein (left)

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38
Q

what do tricuspid and bicuspid valves prevent

A

prevent black flow into the atria

-electrically insulate the ventricles from the atria except AV node

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39
Q

what is the AV node

A

the only conducting path b/w atria and ventricles

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40
Q

when the heart is relaxed, the av valves are

A

open

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41
Q

when the heart contracts, the av valves are

A

closed

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42
Q

what do the aortic and pulmonary valves prevent

A

black flow into the ventricles

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43
Q

when the heart is relaxed, the aortic and pulmonary valves are

A

closed

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44
Q

when the heart contracts, the aortic and pulmonary valves are

A

open

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45
Q

durin isovolumeric contraction, how are the valves

A

all valves are closed

blood does not move in or out of ventricles

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46
Q

describe the path of blood flow

A 
start at right heart with O2 poor blood
-right atrium 
-tricuspid valve
-right ventricle
-pulmonary valve 
-pulmonary circulation
-pulmonary artery
-pulmonary capillaries
(gas exchange)
-pulmonary veins
return to the left heart with O2 rich blood
-right atrium
-mitral valve
-right ventricle
-aortic valve 
-aorta
-branching arteries
-systemic capillaries
(gas exchange)
-systemic veins
-SVC and IVC
-return to right of heart
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47
Q

what is the electrical activity of heart

A

the heart beats rhythmically as a result of action potentials

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48
Q

what are the two types of muscle cells

A
  • contractile cells

- autorhythmic cells

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49
Q

what do contractile cells do

A
  • mechanical work of pumping
  • do not initiate their own AP
  • ex: neurons, skeletal muscles, heart muscles
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50
Q

what do autorhythmic cells do

A
  • specialized cells that initiate and conduct AP
  • display pacemaker activity
  • ex: pacemaker tissues, SA node, AV node, atrial foci, ventricular foci
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51
Q

what are the components of the conducting system of the heart

A

specialized cardiac muscle in SA node, AV node, and atrioventricular bundle w/ right and left terminal branches
-perkinje fibers

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52
Q

what are perkinje fibers

A

specialized cardiac muscle fibers that form the conducting system of the heart

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53
Q

what is the function of the conducting system of the heart and what influences it

A
  • responsible for generating rhythmic cardiac impulses and conducting them rapidly throughout myocardium
  • influenced by autonomic nerve supply of heart
54
Q

how does the parasympathetic and sympathetic system influence the heart

A
  • parasympathetic: slows the rhythm and diminish speed of conduction
  • sympathetic: does opposite of parasympathetic
55
Q

what do the internal pathways do and how many are there

A
  • 3 intermodal pathways
  • in atrial wall
  • help impulses travel from SA node to AVB node more rapidly than they can pass through the muscle of heart
56
Q

anterior internodal pathway

A

leaves anterior end of SA node and passes anterior to the SVC to end in AV node

57
Q

Bachmann’s bundle

A
  • aka interartrial tract

- branch of anterior internal tract that resides on inner of left atrium

58
Q

middle internodal pathway

A

leaves posterior of SA node and passes posterior to SVC and ends in AV node

59
Q

posterior internodal pathway

A

leaves posterior of SA node and down through cresta terminalis to end in AV node

60
Q

sinuatrial node

A
  • wall of right atrium, to the right of opening of SVC
  • origin spontaneously to rhythmical impulses that spread in all direction through the cardiac muscle of the atria
  • result in atria muscle contracts
61
Q

atrioventricular node

A
  • lower part of right atrium just above attachment of spatial cusps of the tricuspid valve
  • impulse conducted from atria to ventricles
  • speed is slow to allow sufficient time for atria to empty blood into ventricles completely
62
Q

atrioventricular bundle

A
  • aka Bundle of His
  • only pathway that connects myocardium of atria to myocardium of ventricles electrically
  • only route of impulse from atria to ventricles
63
Q

what is the only route of impulse from atria to ventricles

A

atrioventricular bundle

or bundle of HIS

64
Q

where is the atrioventricular bundle

A

bundle descended through fibrous skeleton to membranous part of ventricular septum, then divides into two branches (R & L)
-become continuous with the fibers of Purkinje plexus

65
Q

what does electrical communication start with

A

starts with AP in autorhythmic cells

66
Q

what is the pathway of electrical conduction that coordinates contractions

A
  • electrical communication starts with AP in autorhythmic cells
  • depolarization spreads quickly to adjacent cells through gap junctions in intercalated disks, followed by wave of contraction that goes to atria then ventricles
  • heart contracts as a functional syncytium
67
Q

what does contract as a function syncytium mean

A

atria as well as ventricles contract as a single unit

68
Q

what is normal sinus rhythm driven by

A

SA node

69
Q

what is junctional rhythm driven by

A

AV node

70
Q

what is 1st degree heart block

A

-prologation of the p-q interval due to refractoriness of conductive cells in the AV node

71
Q

what is 2nd degree of heart block

A

a fraction of atrial depolarizations are conducted through the AV node

  • results in more P waves than QRS complexes
  • block may be before or below bundle
  • below bundle = more severe
72
Q

what is 3rd degree of heart block

A

complete heart block, no atrial depolarization s are conducted through the AV node

  • intrinsic depolarization of ventricles (about 32 bpm) often result in syncope
  • condition is one most common requiring artificial pacemaker
73
Q

what does ectopic foci cause

A

may cause premature atrial or ventricular contractions which prevent proper ventricular filling

74
Q

atrial contraction

A
  • starts in SA node and spreads throughout both atria via gap junctions
  • two conduction pathways to speed up conduction
75
Q

what are the two conduction pathways that speed up conduction in atrial contraction

A
  • interarterial pathway: SA node branch off of the anterior internodal pathway to left atrium: Bachmann’s Bundle, ensures that both atrias depolarize to contract simultaneously
  • internodal pathway: SA node to AV node (3 nodes: anterior, middle, posterior), ensures sequential contracting of the ventricles following atrial contraction
76
Q

ventricular contraction

A
  • ATP is conducted slowly at AV node b/c fewer gap junctions

- one way conduction through the AV bundle prevents re-entry of action potentials from ventricle to atria

77
Q

what is the effect of ATP being conducted slowly at AV node

A

-causes AV nodal delay to enable atria to completely depolarize and contract before ventricles do

78
Q

pacemaker potential

A

slow depolarization due to opening of Na+ channels and closing of K+ channels

79
Q

depolarization happens when

A

AP begins when pacemaker potential reaches threshold

-is caused by Ca2+ influx through Ca 2+ channels

80
Q

depolarization happens when

A

Ca2+ channels inactivating

-K+ channels opening causing K+ influx, which results in membrane potential back to most negative voltage

81
Q

what is the voltage of unstable membrane potential

A

-60 mV

82
Q

what is the threshold membrane potential

A

-40 mV

83
Q

what happens whenever pacemaker potential depolarizes to threshold

A

autorhythmic cell fires an AP

84
Q

how long does AP usually last

A

200 msec or more

85
Q

what is the refractory period

A

time following AP which a normal stimulus cannot trigger a 2nd AP until an excitable membrane has recovered

86
Q

what is the purpose of a refractory period

A

to protect the heart to ensure alternating periods of contraction and relaxation

87
Q

what are the three types of ions that determines all aspects of conduction, contraction, and repolarization?

A
  • calcium (Ca++) ions: cause myosite contraction
  • potasium (K+) ions: outflow causes repolarization
  • sodium (Na+) ions: produces cell to cell conduction (of depolarization) I the heart, except in AV node b/c of slow movement of Ca2+ ions
88
Q

bradychardia

A

heart rate less than 60 bpm

89
Q

tachychardia

A

heart rate greater than 100 bpm

90
Q

normal heart rate

A

60-100 bpm

91
Q

describe the systole/diastole ion pathway

A
  • Ca2+ influx stops at the end of systole
  • movement reversed = now Ca2+ is pumped into sarcoplasmic reticulum by Ca2+ pump
  • phosphorylation of troponin 1
  • binding of Ca2+ to troponin C
  • binding sites b/w actin and myosin are blocked
  • diastole: Ca2+ surplus removed by a 3 Na+ - 1 Ca2+ exchanger and by an electrogenic Ca2+ pump
92
Q

describe the Ap of cardiac contractile cells

A
  • phase 4: resting membrane potential: -90 mV
  • phrase 0: depolarization: voltage gated Na+ channels open, Na+ enter cell and rapidly depolarize
  • phase 1: initial repolarization: Na+ channels close, cell begins to repolarize as K+ leaves through open K+ channels
  • phase 2: plateau: combo of Ca2+ influx and decrease K+ efflux
  • phrase 3: rapid repolarization: slow K+ channels open, K+ exits rapidly, returning cell to resting potential
93
Q

mechanical events of cardiac cycle

A

heart contracts to empty and relaxes to fill

both the atria and ventricle have their own cycles of systole and diastole

94
Q

systole:

A

contraction and emptying

spread of excitation

95
Q

diastole

A

relaxation and filling

subsequent repolarization

96
Q

early diastole

A

atria and ventricles relaxed
ventricular pressure is close to zero
AV valve are open
80% of ventricular filling occurs

97
Q

late diastole (atrial contraction)

A

atrial pressure is increased causing increase blood in ventricle
ventricular pressure increases slightly

98
Q

end diastole volume (EDV)

A

volume of blood in ventricle at the end of diastole

99
Q

isovolumetric ventricular contraction (early systole)

A
  • beginning of ventricular systole
  • impulse travels to AV node to excel ventricule
  • sharp rise in ventricular pressure
  • AV valve closed and SL valves closed
  • ventricular volume does not change
100
Q

ventricular ejection (systole)

A
  • ventricular pressure greater than aortic pressure
  • aortic valve opens, ventricular volume decreases
  • rise in aortic pressure from blood volume entering faster than leaving aorta
  • about 2/3 (65 %) of blood in ventricles is ejected into arteries
101
Q

stroke volume

A

volume of blood ejected from each ventricle in a single contraction/beat
SV = EDV - ESV

102
Q

_____ of blood is ejected during systole

A

-not all of blood is ejected during systole

103
Q

end systolic volume (ESV)

A

volume of blood in ventricle at the end of systole

104
Q

ejection fraction

A

SV/EDV

105
Q

isovolumetric ventricular relaxation ( early diastole)

A

both AV and pulmonary valve closed

no blood enters or leaves

106
Q

cardiac output

A

amount of blood pumped out of a ventricle per minute

  • calculated as the product of heart rate and stroke volume
  • CO = SV x HR
107
Q

heart rate

A

determine by autonomic influence on the AV node

108
Q

how does the parasympathetic innervation effect heart rate

A

decrease heart beat
decrease cardiac output
decrease AV node conduction (via Vagus nerve)
-primarily supplies atrium (esp SA and AV nodes) and the ventricles

109
Q

how does the sympathetic innervation effect heart rate

A 
increase heart rate 
increase cardiac output 
increase contractility 
increase AV node conduction (shorten P-R interval) 
-supplies the atria and ventricles
110
Q

conduction velocity is altered by

A
  • increase sympathetic stimulation and adrenergic drugs (norepinephrine, epic, phenylephrine)
  • decrease parasympathetic stimulation (vagus), ischemia, hypoxia and beta blockers
111
Q

nenoates can only change their ___ and not their ___

A

heart rate and not their SV

112
Q

stroke volume is regulated by three things…

A

preload
contractility
afterload

113
Q

preload

A

frank starling law states that critical factor controlling stroke volume is the degree of stretch of cardiac muscles cells immediately before they contract
-preload affected by venous return to heart and volume status

114
Q

EDP

A
  • aka end diastole pressure

- estimated by LAP, RAP, CVP

115
Q

contractility

A

stretch allows the sarcoma to contract farther, generating more force

116
Q

afterload

A

ventricular pressure must be overcome before blood can be ejected from the heart

  • indicated by the diastolic blood pressure
  • PVR effects the right ventricle
  • SVR effects the left ventricle
  • affected by vasoconstriction, vasodilation, obstructure lesions
117
Q

othostatic hypertenstion

A

“postural hypertension”

  • common form of low blood pressure
  • occurs after a change in body positioning: when stands up from a seated or lying position
  • occurs from a decrease in cardiac output
  • causes: hypovalemia, bp meds, psychiatric medications
118
Q

coronary circulation

A
  • heart receives about 5% of cardiac output
  • coronary blood flow is about 250 ml/min
  • increases in myocardial oxygen demand must be met by an increase in coronary blood flow
119
Q

coronary blood flow occurs predominantly during

A

diastole

120
Q

blood pressure

A
  • force exerted by the blood against a vessel wall
  • highest in arteries
  • lowest in veins
121
Q

pulse pressure

A

pressure different b/w systolic and diastolic pressure

122
Q

mean arterial pressure (MAP)

A

average pressure driving blood forward, monitored and regulate by the body

  • MAP = diastolic pressure + (1/3) x pulse pressure
  • 2/3 cardiac cycle in diastole
  • 1/3 in systole
123
Q

velocity of blood flow: where does it change and where is it fastest

A
  • changes as it passes through systemic circulation
  • fastest in aorta
  • declines as vessel diameter decreases and then increases on the venous side as vessel diameter increases again
124
Q

what causes an increase in blood volume

A

increase bp, cardiovascular system, and kidneys to maintain homeostatic balance

125
Q

what is blood distribution determine by

A

diameter of the veins

126
Q

what does venous constriction forces

A

more blood into arterial circulation = increase cardiac output

127
Q

neural control of the heart is done by

A

sympathetic and parasympathetic stimulation

128
Q

sympathetic stimulation

A

speeds up the SA node and vagal activity slows the node

  • norepinephrine (NE) from sympathetic transmitter
  • adrenaline (EPI) from adrenal glands: cause increase contractility, frequency, conduction, velocity, and irritability
129
Q

parasympathetic stimulation

A

by ACH, activating muscarinic receptors and vagal simulation
-reduces contractility, frequency, conduction velocity, and irritability

130
Q

sympathetic (thoracolumbar) fibers

A
  • arise from cervical and upper thoracic portions of the sympathetic trunk
  • end of SA node, AV node, cardiac muscle fibers, and coronary arteries
131
Q

parasympathetic (craniosacral) fibers

A
  • comes from vagus nerve
  • terminate on SA node, AV node, and coronary arteries
  • NOT ON CARDIAC MUSCLE FIBERS

Cardiovascular Physiology (1 decks)

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