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Physiology > Cardiovascular > Flashcards

Cardiovascular Flashcards

1
Q

Hemodynamics

A

blood flow through blood vessels

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2
Q

hydrostatic pressure

A

pressure exerted by a fluid

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3
Q

F=ΔP/R

A

F = flow
ΔP = pressure difference between two fixed points
R = resistance to flow

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4
Q

flow

A

high to low pressure
ΔP > R

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5
Q

no pressure difference

A

= no flow

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6
Q

pressure gradient

A

creates flow
differences in pressure move blood

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7
Q

pressure

A

created from contraction of heart chambers
blood exerts pressure on the walls of blood vessels and heart chambers

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8
Q

resistance to blood flow

A

viscosity
length of blood vessel
diameter of vessel

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9
Q

viscosity

A

friction between molecules of a flowing fluid
increased red blood cells

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10
Q

length and diameter of blood vessel

A

determines amount of contact between moving blood and stationary wall of vessel

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11
Q

Poiseuille’s equation

A

only used with laminar blood flow
R = 8ηl / πr^4

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12
Q

laminar flow

A

fluid particles follow smooth paths in layers - each layer moves smoothly past adjacent layers with no mixing

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13
Q

functions of cardiovascular system

A
  • deliver O2 and nutrients, remove waste products of metabolism
  • fast chemical signaling to cells by circulating hormones or neurotransmitters
  • thermoregulation
  • mediation of inflammatory and host defense responses
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14
Q

components of the cv system

A

heart (pump)
blood vessels (pipes)
blood (fluid)

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15
Q

arterioles

A

small branching vessels with high resistance

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16
Q

capillaries

A

transport blood between arterioles and venules
exchange of materials

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17
Q

arteries

A

move blood away from the heart

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18
Q

veins

A

move blood towards the heart

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19
Q

closed circulatory system

A

blood is always in blood vessels or the heart
allows body to generate greater pressures

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20
Q

atria

A

two
thin walled
low pressure chambers
receive blood returning to the heart

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21
Q

apex

A

bottom of heart (left of midline)

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21
Q

ventricles

A

two
forward propulsion of blood

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22
Q

base

A

top of heart
where blood vessels enter

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23
Q

interatrial septum

A

separates left and right atria

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24
Q

interventricular septum

A

separates left and right ventricles

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25
Q

septa

A

dual pump
allows right and left sides to function independently

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26
Q

pulmonary circulation

A

blood leaves the right heart by the pulmonary trunk and is carried to the gas exchange surfaces of the lungs
poorly oxyg. blood enters lungs → O2 diffuses from alveoli to blood → oxyg. blood leaves lungs + returns to left heart

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27
Q

systemic circulation

A

blood leaves the left heart via the aorta → carried to body
oxyg. blood enters tissues → O2 diffuses from blood to tissues → poorly oxyg. blood leaves tissues + returns to right heart via vena cavae

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28
Q

series flow

A

blood must pass through the pulmonary and systemic circuits in sequence

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29
Q

parallel flow

A

within systemic circuit - most organs
each organ is supplied by a different artery = independent regulation of flow to different organs

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30
Q

pericardium

A

fibrous sac surrounding the heart and roots of vessels
has 3 layers

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31
Q

functions of pericardium

A
  • stabilization of heart in thoracic cavity
  • protection of heart from mechanical trauma, infection
  • secretes pericardial fluid to reduce friction
  • limits overfilling of the chambers, prevents sudden distension
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32
Q

fibrous pericardium

A

outside layer

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33
Q

serous pericardium

A

produces the fluid that fills pericardial cavity
- parietal
- visceral

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34
Q

parietal pericardium

A

attached to fibrous pericardium

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35
Q

visceral pericardium

A

epicardium
layer closest to heart

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36
Q

pericardial fluid

A

in the cavity
decreases friction

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37
Q

pericarditis

A

inflammation of pericardium
decreases ventricular filling

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38
Q

cardiac tamponade

A

compression of heart chambers due to excessive accumulation of pericardial fluid
decreases ventricular filling

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39
Q

ventricular walls

A

left ventricle wall is thicker than right ventricle (thicker myocardium)
left develops higher pressures than right

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40
Q

heart wall

A

epicardium
myocardium
endocardium

all four chambers

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41
Q

epicardium

A

visceral pericardium
covers outer surface of heart

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42
Q

myocardium

A

muscular wall
myocytes, blood vessels, nerves

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43
Q

endocardium

A

endothelium covering inner surfaces of heart and heart valves
continuous with endothelium of blood vessels

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44
Q

myocytes

A

cardiac muscle cells
branched (y shaped) and joined longitudinally
striated
one nucleus per cell, many mitochondria

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45
Q

intercalated disk

A

interdigitated region of attachment (where myocytes join)
desmosomes and gap junctions

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46
Q

gap junctions

A

spread action potentials across the atria or ventricles

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47
Q

valves

A

thin flaps of flexible endothelium-covered fibrous tissue attached at the base to the valve rings
made of collagen
leaflets/cusps

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48
Q

valve rings

A

dense fibrous connective tissue
site of attachment for the heart valves

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49
Q

how valves function

A

unidirectional flow of blood through heart
open/close passively due to pressure gradients
- forward p.g. opens one-way valve
- backward p.g. closes one-way valve but it cannot open in opposite direction

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50
Q

atrioventricular valves

A

between atria and ventricles
prevent backflow of blood into atria when ventricles contract

AV valve apparatus: cusps, chordae tendineae, and papillary muscles

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51
Q

tricuspid valve

A

right AV valve
three cusps

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52
Q

bicuspid valve

A

mitral valve
left AV valve
two cusps

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53
Q

chordae tendineae

A

tendinous type tissue
extend from edges of each cusp to papillary muscle

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54
Q

papillary muscles

A

cone shaped
contraction causes the chordae tendineae to become taut (tension)

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55
Q

function of AV valve apparatus

A

prevents eversion of the AV valves into the atria during contraction of the ventricles

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56
Q

semilunar valves

A

between ventricle and artery
3 cusps
no apparatus

prevent backflow of blood from arteries into ventricles when ventricles relax

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57
Q

pulmonary valve

A

between right ventricle and pulmonary trunk

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58
Q

aortic valve

A

between left ventricle and aorta

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59
Q

cardiac skeleton

A

fibrous skeleton of the heart; made of dense connective tissue (does not conduct action potentials = electrically inactive)
separates atria and ventricles
point of attachment for valve cusps, myocardium

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60
Q

cardiac skeleton attachment

A

cardiac muscle attaches to cardiac skeleton
dense connective tissue between valve rings

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61
Q

coronary circulation

A

movement of blood through tissues of the heart

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62
Q

coronary arteries

A

originate at aortic sinuses at base of ascending aorta

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63
Q

coronary veins

A

drain into the coronary sinus, which empties into right atrium

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64
Q

coronary sinus

A

collection of veins joined together to form a large vessel that collects blood from the myocardium of the heart

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65
Q

cardiac syncytium

A

set of cells that act together
how myocytes communicate with each other
functional = excitation spreads over both ventricles or both atria

all or none property

2: atrial and ventricular syncytia

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66
Q

automaticity

A

autorhythmicity
cardiac muscle contracts in the absence of outside stimulation as a result of its own generation of action potentials

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67
Q

two types of myocytes

A

contractile cells - 99%
conducting cells - 1%

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68
Q

contractile cells

A

myocardium
mechanical work → pump, propel blood, do not initiate action potentials

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69
Q

conducting cells

A

initiate and conduct the action potentials
have few myofibrils
make up the conducting system

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70
Q

components of the conducting system

A

sinoatrial node
internodal pathways
atrioventricular node
bundle of His
bundle branches
Purkinje fibers

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71
Q

SA node

A

cardiac pacemaker
initiates action potentials = sets heart rate

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72
Q

internodal pathways

A

stimulus is passed to contractile cells of both atria and to AV node

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73
Q

AV node

A

100 msec delay ensures atria depolarize and contract before the ventricles
(slower pacemaker potential)
allows ventricles time to fill with blood before they contract and shut the AV valve

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74
Q

Bundle of His

A

below AV node; together = only electrical connection between atria and ventricles

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75
Q

bundle branches

A

left and right travel along interventricular septum

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76
Q

Purkinje fibres

A

branch from bundle branches
large number; diffuse distribution
fast conduction velocity → left and right ventricular myocytes depolarize and contract at the same time

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77
Q

Wolff-Parkinson-White Syndrome

A

electrical signals bypass AV node and move from the atria to ventricles faster than normal
accessory pathway transmits electrical impulses abnormally from ventricles back to atria

rapid heart rate (tachycardia), arrythmias

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78
Q

action potential

A

initiate contraction in muscle cells
brought on by rapid change in membrane permeability to certain ions

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79
Q

fast action potential

A

depolarization is instantaneous

in atrial and ventricular myocardium (contractile cells)
in Bundle of His, bundle branches, and Purkinje fibers

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80
Q

slow action potential

A

depolarization is a gradual increase

in SA node and AV node (conducting cells)

81
Q

cardiac action potential

A

phases are due to changes in permeability of cell membrane of myocyte to Na+, K+, and Ca2+ ions

82
Q

K+ gradient at rest

A

[K+] in > [K+] out

83
Q

Ca2+ gradient at rest

A

[Ca2+] out > in

84
Q

Na+ gradient at rest

A

[Na+] out > in

85
Q

pacemaker potential in slow a.p.

A

phase 1
slow depolarization to threshold due to changes in movement of ions

closing of K+ channels
influx of Na+ through F-type channels
influx of Ca2+ through T-type channels

86
Q

depolarization in slow a.p.

A

L-type channels open at threshold = influx of Ca2+

slow phase due to slow movement of Ca2+

87
Q

repolarization in slow a.p.

A

opening of K+ channels and closing of L-type Ca2+ channels
efflux of K+

88
Q

stable resting phase

A

fast a.p.

89
Q

depolarization in fast a.p.

A

opening of fast voltage-gated Na+ channels at threshold

90
Q

notch

A

slight repolarization during fast a.p.
due to transient opening of K+ channels → K+ efflux

91
Q

plateau

A

fast a.p.
Ca2+ enters cell through L-type channels
slow opening of K+ channels → will repolarize cell

shorter in atrial myocardium compared to ventricular

92
Q

repolarization in fast a.p.

A

opening of K+ channels and closing of Ca2+ channels

93
Q

ECG

A

graphic recording of electrical events
electrical activity of the heart (from all myocardial cells) detected on skin surface

94
Q

P-wave

A

spread of depolarization across atria
atria contract 25 msec after start of P-wave

95
Q

QRS-complex

A

spread of depolarization across ventricles
atria repolarize simultaneously (no wave seen)

96
Q

T-wave

A

ventricular repolarization

97
Q

normal ECG

A

p-wave always followed by QRS complex and t-wave

98
Q

partial AV node block

A

not all of stimulus gets through due to cell damage
every 2nd p-wave is not followed by QRS complex

99
Q

complete AV node block

A

no synchrony between atrial and ventricular electrical activities
ventricles driven by slower bundle of His

100
Q

excitation-contraction coupling

A

contraction of cardiac muscle is regulated by Ca2+

101
Q

calcium-dependent calcium release

A

Ca2+ bind to ryanodine receptors → release of calcium from SR

102
Q

L-type Ca2+ channel

A

voltage gated
modified DHP receptor

103
Q

refractory period

A

new action potential cannot be initiated
inactivation of Na+ channels
~250 msec
no response to another stimulus

prevents tetanic contraction

104
Q

tetanic contraction

A

continuous contraction of muscle ex. lifting heavy object
dangerous in cardiac muscle → ventricles couldn’t fill with blood

105
Q

cardiac cycle

A

single heart beat
two parts:
1. systole
2. diastole

106
Q

systole

A

ventricular contraction + blood ejection
myocardial blood flow almost ceases

107
Q

diastole

A

ventricular relaxation + blood filling
myocardial blood flow peaks

108
Q

isovolumetric ventricular contraction

A

all heart valves closed
blood volume in ventricles remains constant → pressure rises
muscle develops tension but cannot shorten

109
Q

ventricular ejection

A

pressure in ventricles exceeds that in arteries
semilunar valves open → blood ejected into the artery
muscle fibers of ventricles shorten

110
Q

stroke volume

A

vol of blood ejected from each ventricle during systole
SV = EDV-ESV
normal: ~70-75 mL

111
Q

isovolumetric ventricular relaxation

A

all heart valves closed
blood volume remains constant → pressure drops

112
Q

ventricular filling

A

AV valves open
blood flows into ventricles from atria
passive + atrial kick

113
Q

passive ventricular filling

A

ventricles receive blood passively; atria are relaxed
70% of ventricle is filled passively

114
Q

atrial kick

A

atria contract at the end of ventricular filling

115
Q

end-diastolic volume

A

amount of blood in each ventricle at the end of ventricular diastole

116
Q

end-systolic volume

A

amount of blood in each ventricle at the end of ventricular systole

117
Q

Lub

A

first heart sound
closure of AV valves

118
Q

Dub

A

second heart sound
closure of semilunar valves

119
Q

sympathetic innervation

A

thoracic spinal nerves → release of NE and E
also from adrenal medulla

beta-adrenergic receptors on atria and ventricles

atria, ventricles, SA node, AV node

120
Q

parasympathetic innervation

A

vagus nerve
release acetylcholine

muscarinic receptor on atria

atria, SA node, AV node

121
Q

cardiac output

A

amount of blood pumped by each ventricle in one minute
CO = HR x SV

122
Q

sympathetic effect on heart rate

A

increase slope of pacemaker potential (faster depolarization)
increase HR
increases F-type and T-type channel permeability

123
Q

parasympathetic effect on HR

A

decrease slope of pacemaker potential (slower depolarization)
decrease HR
decreases F-type channel permeability
hyperpolarizes cells (increase K+ permeability)

124
Q

factors affecting stroke volume

A

EDV
contractility of ventricles
afterload

125
Q

preload

A

tension or load on myocardium before it begins to contract
or
amount of filling of ventricles at the end of diastole (EDV)

126
Q

Frank Starling Mechanism

A

relationship between EDV and SV
preload (degree of diastolic filling) determines the length of cardiac muscle fiber (sarcomere)

increase filling → increase EDV → increase cardiac fiber length → greater force during contraction + greater SV

127
Q

contractility

A

strength of contraction at any given EDV
stimulation of ventricle by sympathetic innervation increases contractility due to increased Ca2+ availability

128
Q

ejection fraction

A

EF = SV/EDV

129
Q

sympathetic effect on contractility

A

decreases length of cardiac cycle
more rapid contraction and more rapid relaxation (maintain diastole)

130
Q

afterload

A

tension (arterial pressure) against which the ventricles contract

as afterload increases, SV decreases

increased by any factor that restricts blood flow through arterial system

131
Q

factors that restrict blood flow through arterial system

A

high arterial blood pressure
vascular resistance (arterial constriction)
stenotic valve (can’t open completely)

132
Q

endothelium

A

smooth, single-celled layer of endothelial cells
lines all vasculature

endothelium of vessels is continuous with endocardium of the heart

blood cells do not adhere to - flow smoothly over

133
Q

artery structure

A

smooth muscle
elastic fibers
connective tissue

134
Q

elastic arteries

A

ex. aorta
many elastic fibers, few smooth muscle cells
expand and recoil in response to pressure changes

135
Q

muscular arteries

A

branch from aorta to distribute blood
many smooth muscle cells, few elastic fibers

136
Q

arterioles - structure

A

smallest arteries
1-2 layers of smooth muscle cells
resistance vessels

137
Q

functions of arterioles

A

determine relative blood flow to individual organs at mean arterial pressure
determine mean arterial pressure (MAP)

cause drop in MAP as distance from heart increases

138
Q

altering arteriolar diameter

A

alters resistance and flow

vasodilation: relaxation of arteriolar smooth muscle → increased blood flow to organs
vasoconstriction: contraction of arteriolar smooth muscle → decreases blood flow to organs

139
Q

arteriole intrinsic / basal tone

A

smooth muscle is partially contracted in absence of external factors
always has low level of activity

140
Q

extrinsic factors alter basal tone

A

factors external to organ/tissue - affect whole body
whole body needs MAP
nerves and hormones can affect state of contraction of arterial smooth muscle

141
Q

intrinsic factors alter basal tone

A

local controls
organs/tissues alter their own arteriolar resistances independent of nerves or hormones

142
Q

sympathetic extrinsic control of arterioles

A

NE → vasoconstriction (a-adrenergic receptors)

increase sympathetic tone = vasoconstriction
decrease sympathetic tone (below basal level) = vasodilation

143
Q

hormonal extrinsic control of arterioles

A

epinephrine release from adrenal medulla

144
Q

active hyperemia

A

local control

increased metabolic activity of organ = local chemical changes [decrease O2, increase metabolites → released into interstitial fluid] → vasodilation of arterioles = increased blood flow
no nerves/hormones are involved

145
Q

flow autoregulation

A

changes in arterial blood pressure alter blood flow to an organ → changes concentration of local chemicals

arterioles change resistance to maintain constant blood flow in presence of pressure change

intrinsic to organ/tissue

146
Q

flow autoregulation: decreased arterial pressure in organ

A

decrease blood flow to organ
decrease O2, increase metabolites, decrease vessel-wall stretch
arteriolar dilation in organ
restoration of blood flow toward normal

147
Q

flow autoregulation: increased arterial pressure in organ

A

increase blood flow to organ
increase O2, decrease metabolites, increase vessel-wall stretch
arteriolar constriction in organ
restoration of blood flow toward normal

148
Q

myogenic response

A

action of myocytes

may mediate flow autoregulation

149
Q

capillaries

A

smallest blood vessel
one endothelial cell thick
no smooth muscle or elastic tissue

exchange of material between blood and interstitial fluid

150
Q

intercellular clefts

A

narrow water-filled space at tight junctions between endothelial cells

small water-soluble substances can pass through

151
Q

basement membrane

A

surrounds endothelial cells of some capillaries
provides support to e. cell
has some connective tissue

152
Q

continuous capillaries

A

small gap junction between endothelial cells
surrounded by complete basement membrane

least permeable capillary
exchange of water, small solutes, lipid-soluble material
most abundant - found in most tissues

153
Q

fenestrated capillaries

A

endothelial cells have fenestrae (pores)
[with or without diaphragm]
surrounded by complete basement membrane
rapid exchange of water and small peptides

found in endocrine organs, choroid plexus (brain), GI tract, kidneys → areas where molecules need to cross the capillaries

154
Q

sinusoidal capillaries

A

most permeable; found in only three specific regions
sinusoids - discontinuous or irregularly shaped (flattened)

large fenestrae in cells; large intercellular clefts between cells
thin or absent basement membrane

free exchange of water and solutes

liver, bone marrow, spleen

155
Q

microcirculation

A

blood circulation between arterioles and venules

arterioles → metarterioles → capillaries → venules

156
Q

metarteriole

A

precapillary arterioles
not capillaries → contain smooth muscle cells
connect arterioles to venules
change diameter to regulate flow

157
Q

precapillary sphincter

A

ring of smooth muscle found at entrance to capillary
can constrict/dilate to alter blood flow into capillary bed
has no innervation
responds to local factors

158
Q

capillary exchange

A

molecules cross endothelial cells by diffusion

159
Q

diffusion

A

movement of substance down its concentration gradient
exchange of nutrients, metabolic products

160
Q

lipid soluble diffusion

A

movement through endothelial cells

161
Q

lipid insoluble diffusion

A

movement through water-filled channels: intercellular clefts, fenestrae, fused vesicle channels

162
Q

transcytosis

A

use of vesicles to cross endothelial cells
endocytic and exocytic vesicles form a water-filled channel across the cell

163
Q

bulk flow

A

movement of protein-free plasma across capillary wall

164
Q

filtration

A

bulk flow from capillary to interstitial fluid

165
Q

reabsorption

A

bulk flow from interstitial fluid to capillary

166
Q

pressures that drive bulk flow

A

hydrostatic pressures (capillary + interstitial fluid)
colloid osmotic pressures (blood + interstitial fluid)

167
Q

capillary hydrostatic pressure

A

pressure exerted on inside of capillary walls by blood
favours movement out of capillary (filtration)

168
Q

interstitial fluid hydrostatic pressure

A

pressure exerted on outside of capillary walls by ISF
favours movement into capillary (reabsorption)
negligible

169
Q

blood colloid osmotic pressure

A

osmotic pressure due to non-permeating plasma proteins inside the capillaries
favours fluid movement into the capillaries (absorption)

170
Q

interstitial fluid colloid osmotic pressure

A

small amount of plasma proteins may leak out of capillaries into interstitial space
favours fluid movement out of capillaries (filtration)
negligible

171
Q

net exchange pressure

A

(Pc + πIF) - (PIF + πC)

starling forces

172
Q

transition point

A

between filtration and reabsorption
lies closer to venous end of capillary = more filtration than absorption

173
Q

venous system

A

~60% of blood volume
large networks in liver, bone marrow, and skin

174
Q

veins

A

high capacitance vessels → store large volumes of blood
highly distensible at low pressures and have little elastic recoil
reservoir of blood

175
Q

venous valves

A

prevent backflow of blood to capillaries
compartmentalize blood

176
Q

varicose veins

A

vein walls weaken + stretch → valves don’t function properly
blood pools and vessels distend

177
Q

mechanisms for venous return

A
  1. smooth muscle in veins
  2. skeletal muscle pump
  3. respiratory pump
178
Q

smooth muscle in veins

A

innervated by sympathetic neurons
stimulation → constriction of smooth muscle

179
Q

skeletal muscle pump

A

compresses veins
venous pressure increases → forces more blood back to heart

180
Q

respiratory pump

A

inspiration = change in pressure of thoracic cavity → increase venous return

181
Q

venous return + Frank starling law

A

increased venous return results in increased stroke volume through the Frank Starling mechanism

182
Q

compliance

A

ability of blood vessels to distend and increase volume with increasing transmural pressure
= change in vol / change in pressure

way to maintain blood flow during diastole

183
Q

transmural pressure

A

pressure across wall of blood vessel
stretches blood vessel

184
Q

elastic recoil

A

when valve closes, recoil pushes blood forward
large arteries function as pressure reservoirs

185
Q

systolic pressure

A

maximum blood pressure during ventricular systole

186
Q

diastolic pressure

A

minimum blood pressure at end of ventricular diastole

187
Q

arterial blood pressure

A

systolic/diastolic pressure = 120/80 mmHg
(left ventricle)

188
Q

pulse pressure

A

difference between systolic and diastolic

189
Q

hypertension

A

chronically increased arterial blood pressure

190
Q

hypotension

A

abnormally low blood pressure

191
Q

mean arterial pressure

A

MAP = diastolic pressure + (pulse pressure/3)
pressure driving blood into tissues

192
Q

pulse pressure

A

decreases as distance from heart increases
disappears at arterioles
smooth flow at capillaries

193
Q

total peripheral resistance

A

determined by total arteriolar resistance

194
Q

short term regulation of MAP

A

occurs within seconds to hours of blood pressure change
baroreceptor reflexes adjust CO and TPR by ANS

195
Q

long term regulation of MAP

A

adjust blood volume by altering salt and water reabsorption
restore normal salt + water balance through mechanisms that regulate urine output and thirst

196
Q

arterial baroreceptors

A

pressure sensors
found in carotid sinus and aortic arch

respond to mean arterial pressure and pulse pressure
respond to changes in pressure when walls of vessel stretch/relax
- degree of stretching is directly proportional to pressure

197
Q

baroreceptor action potential frequency

A

rate of discharge is proportional to mean arterial pressure

198
Q

increase in MAP

A

increases rate of firing of baroreceptors

*receptors adapt to sustained changes in arterial pressure

199
Q

medullary cardiovascular center

A

medulla oblongata - brain stem
receives input from baroreceptors

200
Q

MCC reflex

A

input from baroreceptors →
alters vagal stimulation (para.) to heart and symp. innervation to heart, arterioles, and veins to correct blood pressure

Physiology (12 decks)

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