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KIN 267 > Chapter 20 > Flashcards

Chapter 20 Flashcards

1
Q

functions of heart & blood vessels (3)

A

transport water, gases (O2, CO2, N2), proteins & hormones throughout body

  • regulate temperature & blood pH

facilitate functions of immune system

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2
Q

Location of the heart

A

in the mediastinum

extends from sternum anteriorly to vertebral column posteriorly & lies medially between lungs & pleural membranes that cover them

2/3 of heart’s mass is slightly left of midline

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3
Q

Base of heart

A

posterior surface - formed by atria

tipped up medially & posteriorly

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4
Q

Apex of heart

A

formed by tip of left ventricle

projects inferiorly & laterally to left

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5
Q

Pericardium`

A

membrane that surrounds & protect heart & retains its position in mediastinum

(2) main parts

composed of a tough outer fibrous layer lined by a delicate serous membrane

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6
Q

(2) main parts of Pericardium

A

1) fibrous pericardium
2) serous pericardium

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7
Q

1) fibrous pericardium

A

very dense irregular CT

helps anchor & protect heart

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8
Q

2) serous pericardium

A

deep to fibrous pericardium

thinner, more delicate membrane that forms double layer around heart

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9
Q

(2) layers of serous pericardium

A

1) parietal layer
2) visceral layer

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10
Q

1) parietal layer of serous pericardium

A

adheres to ourmost fibrous layer

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11
Q

2) visceral layer of serous pericardium

A

epicardium

  • inner layer

one of the layers that adheres tightly to surface of heart

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12
Q

Pericardial Cavity

A

space between parietal & visceral layer of serous pericardium

  • contains pericardial fluid that lubricates space (secretion of pericardial cells)
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13
Q

Layers of Heart Wall (3)

A

1) Epicardium
2) Myocardium
3) Endocardium

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14
Q

1) Epicardium

A

thin, transparent outer layer (visceral layer of serous pericardium) - composed of mesothelium

  • fibroelastic & adipose tissue beneath

contains blood vessels, lymphatics, and vessels that supply the myocardium.

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15
Q

2) Myocardium

A

thick middle layer - composed of cardiac muscle

responsible for the pumping action of heart

  • makes up 95% of heart wall
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16
Q

3) Endocardium

A

thin layer of endothelium (simple squamous epithelium of circulatory system) overlaying thin CT layer

  • smooth lining for chambers & covers valves
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17
Q

Chambers of the Heart

A

upper → Right & Left Atria

lower → Right & Left Ventricles

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18
Q

Right Heart

A

right atrium & right ventricle

taking venous blood from body & pumping to lungs for oxygenation

**→ powerspulmonary circuit **

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19
Q

Left Heart

A

left atrium & left ventricle

taking freshly oxygenated pulmonary blood & pumping it systemically

→ powers **systemic circulation **

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20
Q

Top part of heart

A

weak pump → right & left atria

  • loads ventricles by giving an atrial kick before ventricle contract
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21
Q

Bottom part of heart

A

a strong pump consisting of right & left ventricles

  • main pump for pulmonary & systemic circuits
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22
Q

Atrial kick

A

force contributed by atrial contraction immediately before ventricular systole that contributes to 20% increase in blood ejected by ventricles

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23
Q

Chronic Atrial fibrillation

A

no atrial kick

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24
Q

flow of blood is dictated by?

A

pressure differences not muscle

flows from area of high pressure to area of low pressure.

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25
Q

Heart Valves (2)

A

1) Atrioventricular
2) Outflow (semilunar)

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26
Q

1) Atrioventricular

A

open to allow blood to flow from atria into ventricles

located at entrance of ventricles

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27
Q

2) Outflow (semilunar)

A

open to allow blood to flow from ventricles into outflow vessels

located at entrance to outflow vessels leading into pulmonary & systemic circulation

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28
Q

1) Atrioventricular (2)

A

1) tricuspid (right AV) valve
2) bicuspid/mitral (left AV) valve

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29
Q

2) Outflow (semilunar) (2)

A

1) pulmonary (right outflow) valve
2) aortic (left outflow) valve

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30
Q

1) tricuspid (right AV) valve

A

3 leaflets/cusps → opens into right ventricle

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31
Q

2) bicuspid/mitral (left AV) valve

A

opens into left ventricle

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32
Q

1) pulmonary (right outflow) valve

A

opens into pulmonary trunk

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33
Q

2) aortic (left outflow) valve

A

opens into aortic arch

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34
Q

**Operation of Atrioventricular Valves **

  • ventricles relaxed
A

when ventricles relaxed, papillary muscles relaxed & chordae tendinae are slack

blood moves from higher pressure in atria to lower pressure in ventricles through open AV valves

when open, rounded ends of cusps

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35
Q

Operation of Atrioventricular Valves

  • ventricles contracting
A

when ventricles contract, pressure of blood drives cusps upward until edges meet & close opening

papillary muscles contract at same time, pulls on & tightens chordae tendinae to prevent cusps from opening into atria in response to high ventricular pressure

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36
Q

Operation of Semilunar Valves

A

made up of 3 crescent moon-shaped cusps

  • each attached to arterial wall (each = 1/3 of valve)
  • allow ejection of blood from heart into arteries but prevents backflow into ventricles
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37
Q

Operation of Semilunar Valves

  • ventricles contract
A

pressure builds up in chambers

SL valves open when ventricle pressure > artery pressure → ventricular ejection

ejects blood from ventricles into **pulmonary trunk/aorta **

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38
Q

Operation of Semilunar Valves

  • ventricles relaxed
A

SL valves close

  • when blood in aorta/pulmonary outflow tract **leaks back into ventricles **
  • SL cusps act as sails, fill up & free edges contact & close opening
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39
Q

No valves guarding which (2) junctions

A

1) between venae cava & right atrium
2) between pulmonary veins & left atrium

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40
Q

Backflow of blood between:

venae cava & right atrium

pulmonary veins & left atrium

A

as atria contract, small amount of blood flows back into vessels but minimized by the way atria contract

  • which compresses & **nearly collapses venous entry points **
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41
Q

Arteries

A

vessels that always conduct blood away from heart

  • contain oygenated blood (few exceptions)
  • thick-walled & exposed to high pressure & friction forces
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42
Q

Veins

A

vessels that always bring blood back to heart

contain de-oxygenated blood (few exceptions)

thin-walled & exposed to low pressures & minimal friction forces

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43
Q

Arteries carry oxygenated blood - Exceptions?

A

pulmonary arteries (& umbilical)

→carry de-oxygenated blood to lungs (pulmonary capillaries)

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44
Q

Veins carry de-oxygenated blood - Exceptions?

A

pulmonary veins (& umbilical)

→ carry oxygenated blood to **left atrium **

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45
Q

Major arteries that attach to heart

A

1) arch of aorta (ascending &descending)
2) pulmonary trunk (left & right pulmonary arteries)
3) **coronary arteries **

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46
Q

Major veins that attach to heart

(4)

A

1) superior vena cava
2) inferior vena cava
3) pulmonary veins (4)
4) coronary sinus (on back of heart)

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47
Q

(2) circuits of blood flow

A

1) Systemic
2) Pulmonary

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48
Q

1) Systemic Circulation

A

ejects blood into aorta, systemic arteries & arterioles

  • is powered by left side of heart.
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49
Q

1) Pulmonary Circulation

A

ejects blood into pulmonary trunk

  • powered by **right side of heart **
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50
Q

starting with venous return to heart.. blood flow?

A

deoxygenated blood →right atrium from (3) sources →right side of heart → lungs

oxygenated blood → left side of heart to be pumped through outflow tract of systemic circulation

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51
Q

Right Atrium recieves blood from? (3)

A

1) superior vena cava
2) inferior vena cava
3) coronary sinus

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52
Q

left side of heart pumps…

A

oxygenated blood into systemic circulation to all tissues of body except the air sacs (alveoli) of lungs.

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53
Q

right side of heart pumps…

A

deoxygenated blood into the pulmonary circulation to air sacs (alveoli) of the lungs

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54
Q

Blood Flow - complete circle

A

RA → triscuspid valve → RV → pulmonary trunk & arteries → lungs (pulmonary capillaries) - blood loses CO2 & gains O2

Lungs → pulmonary veins → LA → bicuspid valve → LV → aortic valve →aorta & systemic arteries → body systemic capillaries ** **

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55
Q

Coronary Circulation

A

blood circulation in network of blood vessels in myocardium - supplies nutrients

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56
Q

Coronary Circulation

  • HEART CONTRACT/RELAXED
A

coronary arteries branch from ascending aorta

  • encircle heart

when heart contracts, little blood flow in coronary arteries (squeezed shut)

when heart relaxes, high pressure of blood in aorta propels blood through coronary arteries → capillaries → coronary veins

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57
Q

When does blood flow through coronary circulation?

A

only during relaxation phase of ventricular **diastole **

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58
Q

Blood flow through Coronary circulation

  • Coronary **Arteries **
A

aorta → left & right coronary arteries

LCA → anterior interventricular + circumflex branches

RCA → marginal + posterior atrioventricular branches

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59
Q

Blood flow through Coronary circulation

  • Coronary Veins
A

arteries of coronary circulation → capillaries → deliver nutrients & O2 to heart muscle → coronary **veins **

→ coronary sinus → right atrium (de-oxygenated blood joins with that of the rest of body)

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60
Q

Cardiac Muscle Tissue

A

striated

shorter fibers than skeletal muscle

  • branch
  • only 1 central nucleus
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61
Q

Cardiac Muscle Cell Communication

A

connect to & communicate with neighboring cells through gap junctions in intercalated discs

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62
Q

Which tissues of heart can derive oxygen from blood flowing through chambers?

A

innermost tissues

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63
Q

Formation → Autorhythmicity of Heart Muscle Cells

A

During embryonic development, about 1% of all cardiac muscle cells become autorhythmic fibers & form network/ pathway called **cardiac conduction system. **

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64
Q

cardiac conduction system

A

network of specialized cardiac muscle fibers that produce path for each cycle of cardiac excitation to progress through heart

specialized group of myocytes

have ability to spontaneously depolarize

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65
Q

Autorhythmicity

A

rhythmical electrical activity produced by autorhythmic fibers

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66
Q

vBecause heart muscle is autorhythmic, it does not…

A

rely on CNS to sustain lifelong heartbeat

67
Q

cardiopulmonary bypass

A

heart and lung machine reoxygenates blood & pumps it through system

technique that temporarily takes over function of heart and lungs during surgery, maintaining circulation of blood and the oxygen content of body.

68
Q

Autorhythmic cells spontaneously depolarize at a given rate, some groups faster, some groups slower

vOnce a group of autorhythmic cells reaches threshold …

A

starts an AP

→ all cells in that area of heart also depolarize

69
Q

The self-excitable myocytes that “act like nerves” (autorhythmic fibers) have (2) important roles

A

forming conduction system of heart

acting as pacemakers within that system

70
Q

What acts as the normal pacemaker of the heart?

Why?

Location?

A

Sinoatrial (SA) node

because it has fastest rate of depolarization

located in right atrial wall just below where superior vena cava enters chamber.

71
Q

Spontaneous Depolarization of autorhythmic fibers in the SA node fire how often

A

about once every 0.8 seconds

or

75 APs/min

72
Q

SA node - functions as Pacemaker

A

sets rhythm of electrical excitation that causes heart contraction

73
Q

AP from SA node goes where?

A

reaches next pacemaker throughout wall of atria to AV node in interatrial septum

74
Q

AP at AV node…

A

signal is slowed, allowing atrium to mechanically move blood into ventricles

75
Q

From AV node, signal goes where?

A

passes through AV bundle to right & left bundle branches in interventricular septum towards apex of heart

76
Q

from left & right bundle branches in interventricular septum.. where does signal go?

A

towards apex of heart to Purkinje fibers that rapidly conduct AP through ventricles

(0.2 secs after atrial contraction)

77
Q

Natural rhythm of the heart by the SA node

78
Q

Coordinating Contractions of Atria & Ventricles

A

atrial muscle syncytium contracts as single unit to force blood down into the ventricles

syncytium of ventricular muscle starts contracting at apex (inferiorly), squeezing blood upward to exit the outflow tract

79
Q

Cardiac Muscle Action Potential

  • start?
A

AP initiated by SA node travels through conduction system to excite contractile muscle fibers in atria & ventricles

80
Q

contractile fibers

resting membrane potential?

81
Q

AP propogates through heart by?

A

opening & closing Na+ & K+ channels

82
Q

Refractory Period in Cardiac muscle

A

lasts longer than contraction itself

→ meaning another contraction cant begin until relaxation is well underway

(safety mechanism)

83
Q

Tetanus in Cardiac Muscle

A

DOES NOT OCCUR

leaving sufficient time b/w contractions for chambers to fill with blood

84
Q

Complications of tetanus in cardiac muscle

A

heart attack

85
Q

Cardiac Muscle AP

(3) steps

A

1) Depolarization
2) Plateau
3) Repolarization

86
Q

1) Depolarization

A

-90 mV

reaches threshold by AP from neighboring fibers

fast Na+ channels open → Na+ inflow → rapid depolarization

87
Q

2) Plateau

A

period of maintained depolarization → 0.25 sec

partially due to opening of slow Ca2+ channels → Ca2+ inflow

→ causes more Ca2+ from SR → triggers contraction

Just before plateau phase, K+ channels open → K+ outflow

(maintaining depolarization bc Ca2+ inflow balances K+ outflow)

88
Q

3) Repolarization

A

recovery of resting membrane potential

after delay, more K+ channels open → K+ outflow restores negative RMP to -90mV

At same time, Ca2+ channels in SR close

89
Q

Epinephrine

  • released by?
  • effect?
A

release by sympathetic NS

increases contraction force by enhancing movement of Ca2+ into cytosol

90
Q

Electrocardiogram

A

recording of electrical changes on surface of body resulting from depolarization & repolarization of myocardium

91
Q

vECG recordings measure ….(3)

A

the presence or absence of certain waveforms (deflections)

the size of the waves

** time intervals** of the cardiac cycle

92
Q

By measuring the ECG, we can … ?

A

quantify & correlate, electrically, the mechanical activities of the heart.

93
Q

ECG recording can help determine?

A

normal from abnrmal cardiac activity

94
Q

Abnormal ECGs show ?

A

problems within conduction pathways

whether or not heart is enlarged

if cerain regions are damaged

95
Q

Major deflections & intervals in normal ECG include? (4)

A

P wave

P-Q interval

QRS wave

S-T segment

96
Q

P wave

A

atrial depolarization

spreads from SA node through contractile fibers in both atria

97
Q

P-Q interval

A

time from beginning of P wave to beginning of QRS complex

represents conduction time from beginning of atrial excitation to beginning of ventricular excitation

time it takes for atrial kick to fill ventricles

98
Q

QRS wave

A

ventricular depolarization & atrial repolarization

as AP spreads through ventricular contractile fibers

99
Q

S-T segment

A
  • from end of S wave to beginning of T wave*
  • time when ventricular contractile fibers depolarized during plateau*

time it takes to empty ventricles before they repolarize

100
Q

T wave

A

ventricular repolarization

occurs just as ventricles start to relax

101
Q

Correlation of ECG Waves with Atrial and Ventricular Systole
steps (6)

A

1) Depolarization of atrial contrctile fibers → P wave
2) Atrial systole (contraction)
3) Depolarization of ventricular contractile fibers → QRS wave
4) Ventricular systole (contraction)
5) Repolarization of ventricular contractile fibers → T wave
6) Ventricular diastole (relaxation)

102
Q

1) Depolarization of atrial contrctile fibers → P wave

A

AP in SA node → through atrial muscle → AV node

(0.03 sec)

103
Q

2) Atrial systole (contraction)

A

conduction of AP slows at AV node bc fibers have small diameter & gap junctions

result is 0.1-sec delay giving atria time to contract

104
Q

3) Depolarization of ventricular contractile fibers → QRS wave

A

AP enters AV bundle →bundle branches → Purkinje fibers → ventricular myocardium

depolarization

105
Q

4) Ventricular systole (contraction)

A

after QRS complex, continues during S-T segment

As contraction proceeds from apex toward base of heart, blood is squeezed upward toward SL valves.

106
Q

5) Repolarization of ventricular contractile fibers → T wave

A

repolarization of ventricular contractile fibers begins at apex & spreads throughout ventricular myocardium

T wave 0.4 sec after onset of P wave

107
Q

6) Ventricular diastole (relaxation)

A

after T wave begins, ventricles start to relax

By 0.6 sec, ventricular repolarization = complete

108
Q

Although heart does not rely on outside nerves for its basic rhythm, there is …?

A

abundant sympathetic & parasympathetic innervation which alters rate and force of heart contractions.

109
Q

Role of ANS input

A

regulate changes in:

BP

blood flow

blood volume to maintain enough cardiac output to provide for all organs 24/7

110
Q

Input to CV center

A

FROM:

higher brain centers → cerebral cortex, limbic system, hypothalamus

sensory receptors →, proprio, chemo, baroreceptors

111
Q

Output to heart

A

CV center

  • cardiac accelerator nerves (sympathetic)
  • vagus (cranial nerve X, parasympathetic)
112
Q

cardioacceleratory center

  • location
  • recieves info from?
A

in medulla

sensory info from baroreceptors in carotid body & in arch of aorta relay info about BP & blood flow to cardioacceleratory center

113
Q

Nervous system regulation of heart

A

originates in CV center in medulla

114
Q

Sympathetic nerves of heart

A

present throughout atria (especially in SA node) & ventricles

115
Q

Effect of Sympathetic activity

A

increases heart rate & strength of myocardiac contraction to increase blood flow out of heart (ejection fraction)

116
Q

cardioinhibitory center

  • made up of?
    • input?
A

made up of cell bodies of neurons in medula

same sensory info coming in from peripheral baroreceptors goes here

117
Q

Vagus Nerves (Parasympathetic & Cranial X Nerves)

- effect?

A

decreases heart rate (but not contractility bc few PS nerves innervate ventricles)

slows heart from its native rate of 100 bpm to about 70-80 in avg adult

118
Q

Proprioreceptors

A

monitors movement

119
Q

Chemoreceptors

A

monitor blood chemistry

120
Q

Baroreceptors

A

monitor blood pressure

121
Q

Hypocapnia

A

state of reduced carbon dioxide in the blood

122
Q

Mechanism of contraction in Cardiac muscle

A

electrical activity → Ca2+ release from SR → actin & myosin filaments go through contraction cycle → tension develops as filaments slide past one another

123
Q

Epinephrine & Cardiac contraction
- released by?

- effect?

A

released by sympathetic NS

increases contraction force by enhancing movement of Ca2+ into cytosol

124
Q

Pacemaker potential

A

spontaneous depolarization is a pacemaker potential

125
Q

Blood Pressure

  • measured in?
A

large conducting arteries where high & low pulsations of heart can be detected

(usually brachial artery)

126
Q

Systolic BP

A

higher pressure measured during left ventricular systole when aortic valve is open

127
Q

Diastolic BP

A

lower pressure measured during left ventricular diastole when valve is closed

128
Q

systole

A

contraction

129
Q

diastole

A

relaxation

130
Q

Normal BP

A

varies by age but ~120 mmHg over 80 mmHg in healthy young adult

(in females, pressures are often 8-10 mmHg less)

131
Q

People have low BP if…? (2)

A

in good physical condition

favorable genetic predisposition

132
Q

Best way to refer to BP

A

as a single number → mean arterial pressure (MAP)

133
Q

mean arterial pressure (MAP) = ?

A

roughly 1/3 of way between diastolic & systolic BP

1/3(systolic BP - diastolic BP) + diastolic BP

gives us an idea of average pressure experienced by blood vessels during a cardiac cycle

134
Q

Where are BP pulsations not detectable?

A

In smaller arterioles, capillaries & veins

→ only mean BP is measurable

135
Q

Cardiac Cycle

A

all events of one heartbeat

including diastole (relaxation) & systole (contraction) of atria & ventricles

136
Q

In each Cardiac Cycle..

A

atria & ventricles alternatively contract

all 3 heart valves open & close

137
Q

Auscultation

A

listening (usually with stethoscope) to sound heart makes

138
Q

“Lubb Dupp” sounds associated with Auscultation

A

produced by valve closure (valve opening usually silent)

139
Q

During Atrial Systole…

(4)

A
  1. 1 sec → atria contracting while ventricles relaxed
    1) Depolarization of SA node → atrial depolarization (P wave)
    2) causes atrial systole → atria contract → exert pressure on blood within to force it through open AV valves into ventricles
    3) contributes 25 ml to 105 ml of blood →130 mL at end of diastole (end-diastolic volume (EDV))
    4) QRS complex marks onset of ventricular depolarization
140
Q

During Ventricular Systole

(4)

A
  1. 3 sec - ventricles contracting
    1) ventric. depolarization → ventric. systole → P increases → blood pushes against & closes AV valves →

Isovolumetric contraction - both SL & AV valves closed (isovolumetric)

→ cardiac muscle fibers contract & exert force but don’t shorten yet (isometric)

2) when ventric. P > aortic/pulm trunk. P → SL valves open → ventricular ejection (0.25 sec)

3) ventricles ejects 70 mL into aorta/pulm trunk
volume remaining in ventricle after systole (60 mL) = end-systolic volume

4) T wave marks onset of ventricular repolarization

141
Q

During Relaxation Period

(2)

A

0.4 sec → both atria & ventricles are relaxed

1) ventric. repol. causes ventricular diastole
pressure falls → backflow from aorta/pulm trunk closes SL valves

dicrotic wave produced by rebounded blood of closed cusps of aortic valve

isovolumetric relaxation (all 4 valves closed)

2) when ventricular P < atrial P → AV valves open → ventricular filling

142
Q

end‐diastolic volume (EDV)

A

~ 130 ml

volume of blood in ventricles at end of its relaxation period

143
Q

Stroke Volume

A

volume ejected per bear from each ventricle

144
Q

Dicrotic Wave

A

produced by blood rebounding of aortic valve cusps

145
Q

End-Systolic Volume (ESV)

A

volume remaining in each ventricle at end of systole

~60 mL

146
Q

Average time required to compled cardiac cycle

A

usually less than 1 second

(0.8 secs at heart rate of 75 BPM)

147
Q

Stroke Volume = ?

A

End-diastolic volume (EDV) - End-systolic Volume (ESV)

EDV - ESV = SV

130 mL - 60 mL = 70 mL

148
Q

Time for:

Atrial Systole

A

0.1 sec

Atria contract (atrial “kick”), ventricles relax

149
Q

During Atrial Systole, __ are relaxed

A

ventricles

150
Q

During Ventricular Systole, ___ are relaxed

151
Q

Time for:

Ventricular Systole

A

0.3 sec

atria relax, ventricles contract

152
Q

Time for:

Relaxation Period

A

0.4 sec

allowing passive filing

atria & ventricles relaxed

153
Q

Cardiac Output (CO)

A

volume of blood ejected from each ventricle into aorta/pulmonary trunk each minute

154
Q

Cardiac Output (CO) = ?

A

Cardiac Output (CO) = Stroke Volume (SV) x Heart Rate (HR)

CO (ml/min) = SV (mL/beat) x HR (beats/min)

155
Q

On average, a person’s entire blood volume flows through pulmonary and systemic circuits each ____.

156
Q

cardiac reserve

A

difference between Cardiac Output (CO) at rest & maximum CO heart can generate

157
Q

Average cardiac reserve = ?

A

4-5 times resting value

158
Q

Exercise draws upon _ _ to meet __ ___ demands & maintain __

A

Exercise draws upon cardiac reserve to meet increased physiological demands & maintain homeostasis

159
Q

The cardiac output is affected by changes in..? (3)

A

SV

heart rate

both

160
Q

(3) important factors that affect SV

A

1) amount of ventricular filling before contraction
2) contractiliy of ventricle
3) resistance in blood vessels (aorta) or valves (aortic valve, when damaged) heart is pumpinh into (called afterload)

161
Q

Starling’s Law of the Heart

A

the more heart msucle stretches (filed) before contraction (preload), the more forcefully heart will contract

*- SV increases with increase in EDV *

162
Q

Stimulation of **sympathetic NS **during exercise…

A

**increases **venous return, stretches heart muscle & increases CO

KIN 267 (12 decks)

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