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PGY 412 > Cardiovascular Physiology 1 > Flashcards

Cardiovascular Physiology 1 Flashcards

1
Q

Average size people have how many liters of blood

A

5.5 liters

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2
Q

What separates the blood into the components

A

centrifugation

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3
Q

Components of the blood and their percentages

A

erythrocytes: 45%, buffy coat: <1%, plasma: 55%

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4
Q

What is the buffy coat made of?

A

leukocytes and platelets; necessary for fighting infection and blood clotting respectively

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5
Q

What is in the plasma?

A

water, dissolved proteins like albumin, ions, metabolites, hormones, antibodies

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6
Q

What are eythrocytes?

A

red blood cells, used for oxygen transport

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7
Q

What is heart failure defined as

A

heart cannot pump enough blood to meet the body’s basal demands

  • it is a progressive disease
  • 35% die within 1 year of diagnosis
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8
Q

What is end-stage heart failure

A

medical treatment has failed, patient needs heart transplant

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9
Q

What is hematocrit?

A

portion of the blood taken up by red blood cells, typically 45%
-depends on ration of RBC’s to plasma

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10
Q

What happens to hematocrit when you are dehydrated?

A

you lose water from your body so your plasma levels go down but red blood cells stay the same level, so the percentage increases (higher than 45%)

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11
Q

Heart beat is divided into two phases:

A

systole and diastole

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12
Q

systolic phase of cardiac cycle

A

blood is pumped out of the ventricles

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13
Q

diastolic phase of the cardiac cycle

A

blood flows from atria into the ventricles

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14
Q

The atria are

A

collecting chambers

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15
Q

the ventricles are

A

pumps

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16
Q

the valves do what

A

control direction

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17
Q

The heart has billions of cells, most are what kind

A

myocytes that look like skeletal muscles fibers

-they are nucleated

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18
Q

What is functional syncytium

A

system of the heart that pumps blood most effectively with a synchronous contraction, coordinated by the electrical system of the heart

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19
Q

Humans have a ___ circulatory system

A

double

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20
Q

Blood is pumped from the right ventricle to the ____

A

lungs; deoxygenated blood goes there for oxygenation

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21
Q

blood is pumped from the lungs to the ____

A

left atrium (returns oxygenated)

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22
Q

the left ventricle pumps freshly oxygenated blood through ____

A

systemic circulation

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23
Q

blood comes from systemic circulation back to _____

A

right atrium (deoxygenated again at this point)

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24
Q

double circulation ensures:

A

every tissue bed in the systemic circulation receives fresh blood, blood flow can be diverted to different parts of the body as demanded by metabolic requirements

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25
Q

the two ventricles pump the same amount or different amounts of blood

A

same amount

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26
Q

How do arterial and venous pressures differ?

A

arterial pressure is a lot more than venous pressures

  • if an artery was exposed, the pressure would make the blood hit the ceiling
  • if a vein was exposed, you would just have bleeding on the surface
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27
Q

Venous pressure is really low because you can change its direction based on?

A

position of your body parts (holding your hand up in the air vs down towards the ground)

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28
Q

If venous pressure rises, what is this a sign of?

A

congestion

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29
Q

Which is higher, pulmonary or venous pressure?

A

pulmonary, although it is still low; typically systolic might be 25

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30
Q

If pulmonary arterial pressure gets too high, what might happen?

A

you could bleed into your lungs

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31
Q

The body can/cannot store blood and unless you are ____, you don’t lose any

A

cannot; bleeding

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32
Q

Cardiac output is defined as

A

the amount of blood pumped by a ventricle per unit time

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33
Q

at rest, the heart typically pumps about _____ per minute

A

5 liters of blood

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34
Q

Since humans have about 5 liters of blood, it takes about __ minute(s) for a red blood cell to return to the left ventricle after is has been pumped out of the aorta

A

one

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35
Q

to leave the left ventricle, blood must travel through the

A

aorta

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36
Q

typical amount of time spent in systole versus diastole

A

1/3 time in systole (1/3 second), 2/3 time in diastole (2/3 second)

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37
Q

overview of systemic circulation pressures from left ventricle back to right atrium

A

left ventricle: pressures alternate between high up to 120 and low 0
large arteries: arterial pressure is high, stays closer to 120 most of the time
resistance vessels (arterials): lower pressure
capillaries: lower pressure
veins: lowest pressure

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38
Q

Resistance vessels (arterials) have a lower or high cross sectional area

A

lower

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39
Q

capillaries have a lower or high cross sectional area? why?

A

higher because you want to blood to move slow here to allow time for gas exchange

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40
Q

A man is sleeping horizontally. What is the mean pressure in his left ventricle?

A

a. 5 mmHg
b. 55 mmHg
c. 95 mmHg
d. 120 mmHg

mean pressure means the average pressure in the left ventricle. we know that pressure alternates between 0 and 120 in the ventricle, so the average cannot be 5 or 120, but 55 is close to being right in the middle (55+55=110) so that is close to 120 total

*we would not use the MAP calculation here because it is not asking about mean ARTERIAL pressure, it is asking about mean ventricle pressure

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41
Q

common cause of heart attack (myocardial infarction)

A

blockage in coronary artery

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42
Q

symptoms of heart failure

A

exercise intolerance, peripheral and pulmonary edema

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43
Q

Two ways to classify heart failure

A

systolic heart failure: ventricles don’t eject blood properly
diastolic heart failure: heart failure with preserved ejection fraction, ventricles cannot pump because they are not filling properly

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44
Q

left sided heart failure symptoms

A
  • respiratory problems because blood backs up in the lungs when it is not pumped onwards by the left ventricle
  • dyspnea (shortness of breath)
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45
Q

right sided heart failure symptoms

A

occurs when blood backs up in the systemic circulation

-ascites (fluid accumulation in the abdomen)

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46
Q

symptoms of heart attack

A

chest, neck, should pain and a crushing pressure on the chest; symptoms in women are more vague, often confused with GI issues and heart burn

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47
Q

what happens during a myocardial infarction

A
  • blood flow to heart is restricted
  • the affected part becomes ischemic
  • when the flow is restored, the tissue is often damaged as a result of reperfusion injury
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48
Q

Why are patients who survive a heart attack left with damaged ventricles and a higher risk of heart failure?

A

Because heart muscle cannot repair itself the same way skeletal muscle can so it puts them at a higher risk for failure later on

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49
Q

flow=

A

linear speed of fluid times cross sectional area

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50
Q

How can you increase flow?

A

by making fluid move faster or having a bigger pipe

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51
Q

why does blood flow through systemic circulation

A

systolic contractions produce a pressure difference between the left ventricle and right atrium

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52
Q

Ohm’s law defines flow for a given pressure difference as

A

flow= pressure difference/resistance

pressure difference is the pressure at the beginning of the pipe minus the pressure at the end of the pipe

resistance is how hard it is to move the fluid through the pipe, can be affected by diameter

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53
Q

Poiseuille’s law defines resistance as

A

8(n= viscosity) x Length / pi (radius to fourth power)

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54
Q

flow increases or decreases with the pressure drop along the tube

A

increases

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55
Q

flow increases or decreases with the 4th power of the radius

A

increases

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56
Q

flow decreases or increases with fluid viscosity

A

decreases as viscosity goes up

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57
Q

flow decreases or increases with the length of the tube

A

decreases as the tube gets longer

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58
Q

if resistance increases, flow

A

decreases

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59
Q

if the pressure difference increases, flow rate

A

increases

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60
Q

what happens to resistance with a wider pipe (increased radius)

A

resistance decreases with increasing radius

61
Q

how can we increase fluid viscosity

A

increase hematocrit (normal is 45%)

62
Q

Why does poiseuille’s law not apply to capillary blood flow?

A

because the red blood cells have to squeeze through the small capillaries and flow becomes non-newtonian

63
Q

Some participants in endurance sporting events illicitly increase the number of red blood cells in their circulation by blood doping. Why does this elevate their physical performance? How does their hematocrit change? What happens to their total peripheral resistance (the resistance of their systemic circulation)?

A
  1. blood doping increases their ability to transport oxygen to their muscles
  2. hematocrit increases
  3. total peripheral resistance goes up because hematocrit increases viscosity
64
Q

Blood is flowing through an artery at a rate of 20 cubic centimeters per second. The artery has a cross sectional area of 4 cm2. What is the blood’s average velocity?

A

5 cm s-1

65
Q

Blood is flowing out of a reservoir through a tube. The length of the tube us suddenly doubled. The flow rate changes to ____% of its original value.

A

50%; flow decreases

66
Q

Is the average pressure in the right atria greater than, less than, or equal to the average pressure in the aorta?

A

less than- the pressure difference between the aorta and right atrium is driving blood around the systemic circulation

67
Q

Most numerous cell type in the blood

A

erythrocytes

68
Q

what do erythrocytes do

A
  1. oxygen molecules from the lungs to other tissues

2. carbon dioxide molecules produced by tissues back to the lungs

69
Q

What do leukocytes do

A

white blood cells that fight infection, 5 different types

70
Q

What are platelets

A

cell fragments that play a crucial role in the mechanisms that stop bleeding (blood clotting)

71
Q

how big is a erythrocyte

A

about 7um

72
Q

do erythrocytes have a high or low surface area? what does this allow for?

A

high surface area, allows gases to move quickly in and out of their interiors

73
Q

What is in the plasma membrane of an erythrocyte

A

contain polysaccharides and proteins that define a person’s blood type

74
Q

Do erythrocytes have a nucleus and organelles

A

No nucleus and lack most organelles

75
Q

Can red blood cells repair themselves?

A

No, due to the lack of nucleus and most organelles

76
Q

How long does a RBC typically last?

A

about 120 days which means that 1% of them (250 billion) have to be replaced every 24 hours

77
Q

What hormone regulates red blood cell replacement

A

erythropoietin

78
Q

state the negative feedback loop for restoration of O2 delivery

A

decreased O2 delivery to kidneys -> kidneys increase erythropoietin secretion -> plasma erythropoietin is increased -> bone marrow increases production of erythrocytes -> blood hemoglobin concentration is increased -> blood oxygen carrying capacity is increased -> restoration of O2 delivery

79
Q

sickle cell anemia

A

a genetic disorder which is manifested fully only in people who are homozygous to the mutation, heterozygotes are protected from malaria (because malaria doesn’t do well in jagged cells)

80
Q

Why is there an evolutionary pressure for sickle cell anemia in places with high malaria rates?

A

malaria cannot live in jagged cells, therefore this gene might be selected in order to prevent people from contracting malaria; however, they would have sick cell anemia and would likely die in their 40s, but would still live longer than if they caught malaria

81
Q

Why is sickle cell anemia painful?

A

the shape of the red blood cells causes them to get stuck in the capillaries so the tissue is not properly oxygenated and this causes severe pain

82
Q

neutrophil percentage and broad overview

A

65%, kill bacteria and fungi by phagocytosis, release chemicals involved in inflammation, main constituent of pus

83
Q

eosinophil percentage and overview

A

4%, destroy parasites, predominate inflammatory cells in allergic reaction

84
Q

If eosinophil percentage increases, what might this indicate?

A

that a person might have a parasitic infection

85
Q

basophil percentage and overview

A

less than 1%, release histamine and other chemicals involved in inflammation; similar to mast cells

86
Q

monocytes percentage and overview

A

6%, phagocytosis; similar to macrophages in other tissues

87
Q

lymphocytes percentage and overview

A

25%, 3 classes- b cells, t cells, nk cells

-responsible for immune response, production of antibodies, etc.

88
Q

What is the normal range for white blood cells (leukocytes)?

A

4.5 to 11.0 x 10^9 cells per liter, a person that is 1.5 x 10^9 cells per liter can leave an individual susceptible to infection

89
Q

Why are blood counts often reduced during anti-cancer treatments such as radiation or chemotherapy?

A

cancer is uncontrolled cell growth and the treatment targets rapidly dividing cells and it cannot differentiate between rapidly dividing blood cells and rapidly dividing cancer cells

90
Q

hemostasis is

A

prevention of blood loss

91
Q

Two mechanisms for hemostasis by the body

A

formation of platelet plug and blood coagulation, both involving platelets

92
Q

Which mechanism of hemostasis occurs first?

A

platelet plug

93
Q

how do platelets become activated in plugging?

A

when they encounter exposed collagen

94
Q

is platelet plug formation positive or negative feedback?

A

positive

95
Q

chemical that platelets release to promote further aggregation

A

thromboxane A2

96
Q

how do endothelial cells prevent too much platelet plugging so that the entire pipe is not blocked?

A

away from damage, the endothelial cells release NO and PGl2 to prevent platelet activation in good tissue

97
Q

NO and PGI2 do what?

A

prevent platelet adhesion, activation, and aggregation

98
Q

clotting involves a complex cascade that turns soluble fibrinogen into ____ which forms ____

A

loose fibrin which forms stabilized fibrin

99
Q

fibrin acts as a ____ around the platelet plug

A

mesh

100
Q

What happens if a clot breaks free from the vascular wall?

A

it can circulate in the blood-stream before lodging in a critical vessel

101
Q

What happens if a blood clot gets lodged in a vessel within the brain

A

could result in a stroke

102
Q

What happens if a blood clot blocks the coronary artery

A

can result in myocardial infarction

103
Q

What is warfarin (coumadin)?

A

a blood thinner uses to reduce the probability of clot formation in the blood by inhibiting certain chemical factors; commonly used in patients with atrial fibrillation who are at increased risk of developing clots in their atria because of altered flow patterns

104
Q

why is aspirin taken to reduce risk of heart attack and stroke?

A

reduces production of thromboxane A2

105
Q

Vioxx is a pain killing drug that has the potential to do what

A

increase the risk of blood clot formation

106
Q

which cells initiate heart beat?

A

pacemaker cells in the SA node; these cells have the fastest spontaneous rhythm in the heart

107
Q

if the SA node fails, what takes over

A

pacemaker cells in the AV node can set a slower ventricular rhythm

108
Q

Ventricular myocytes are/are not autorhythmic

A

are not autorhythmic and need to be triggered to contract

109
Q

general pathway of pacemaker heart cycle

A

SA node depolarizes, AP propagated through atria to AV node, AV node causes pause and can filter out AP’s from SA node if needed, AV node sends AP’s down septum through bundle of His, AP spreads through perkinje fibers causing ventricles to depolarize and contract, then ventricles return to resting state (electrically silent ventricles)

110
Q

excitation contraction coupling pathway

A

start with excitation (depolarization of plasma membrane) -> opening of plasma membrane L type Ca2+ channels in T-tubules -> flow of calcium into cytosol -> 50% increases cytosolic calcium concentration -> 50% of Ca2+ binds to ryanodine receptors on external surface of SR -> opens calcium channels intrinsic to these receptors -> flow of calcium into cytosol –> increased calcium concentration which leads to contraction

111
Q

Why is the excitation contraction coupling pathway considered to be calium-induced calcium-release?

A

because calcium is required to open more calcium channels in the sarcoplasmic reticulum to release calcium into the cytosol

112
Q

How are myocytes relaxed during diastole?

A

By SERCA pumping calcium ions back into the sarcoplasmic reticulum

113
Q

What molecule regulates SERCA?

A

phospholamban

114
Q

during systole, the free calcium concentration in the cytoplasm increases/decreases/stays the same

A

increases (200 nM in diastole, to 5-10 micro molar in systole)

115
Q

increasing the peak calcium concentration during systole causes the muscle to develop more or less force

A

more force; this is different than skeletal muscle because the amount of calcium released form the SR is always more than enough to produce maximal force

116
Q

why are calcium channel blockers sometimes used to control blood pressure?

A

they reduce the peak systolic calcium concentration so the amount of pressure the heart generates during systole goes down

117
Q

how is contraction reduced

A

pumping calcium back into the SR by SERCA or outside the cell

118
Q

Ventricular myocytes have a resting membrane potential around

A

-80 mV

119
Q

-80 mV is close to the equilibrium potential for K+ and reflects

A

the tendency of K+ ions to diffuse out of the cell through open potassium channels down their concentration gradient

120
Q

Why does membrane potential change?

A

due to the opening and closing of channels and similarly, ion channels will open or close based on changes in the membrane potential

121
Q

when the cell depolarizes, the membrane permeability of K+ ____

A

decreases, minimizing number of K+ ions leaving the cell helping to preserve the plateau phase of the action potential

122
Q

rapid upstroke of the action potential is primarily due to opening of

A

voltage gated sodium channels

123
Q

the calcium ions that enter the cell initiate

A

calcium induced calcium release (CICR), also help maintain plateau phase of ventricular action potential

124
Q

cells in the conducting system exhibit

A

automaticity- they are rhythmically self exciting

125
Q

pacemaker cells in the what set the rate at which the heart beats

A

SA node

126
Q

conducting system cells (pacemaker cells) completely lack

A

rapidly acting voltage gated Na channels

127
Q

instead of the fast Na channels, conducting system cells have

A

F-type Na+ channels

128
Q

F type Na+ channels open when

A

the cell is hyperpolarized, which is unusual so the associated current is often referred to as the funny current

129
Q

Nodal cells contain ____ channels that help raise the membrane potential towards threshold

A

T-type Ca2+ channels

130
Q

The upstroke of action potential in nodal cells is determined primarily by inward current through _____ channels

A

L type Ca2+ channels

131
Q

Inside the cell, there is ____ concentrations of Na+, K+, Ca2+

A

low Na+, High K+, Low Ca2+ inside the cell

132
Q

What happens during each phase of cardiac myocite action potential

A 
Phase 0: rapid depolarization
Phase 1: initial repolarization
Phase 2: plateau
Phase 3: repolarization
Phase 4: resting potential restored
133
Q

ECGs are commonly used to

A

diagnose arrhythmia or electrophysiological problems with the heart

134
Q

heart trace components on ECG

A

P wave (atrial depolarization), QRS complex (ventricular depolarization), T wave (ventricular repolarization)

135
Q

The refractory period for a cardiac ventricular cell is much longer than that of a skeletal muscle cell. Why is that helpful?

A

stops the heart from going into tetanic contraction

136
Q

True or False: The t wave on an ECG trace indicates opening of the aortic valve

A

false. T wave is ventricular repolarzation which is the end of systole

137
Q

which part of the heart would set the ventricular rhythm if the SA node was damaged?

A

AV node

138
Q

Most of the current flowing through the cell membrane in the late plateau of a ventricular myocyte action potential passes through

A

voltage gated L type calcium channels

note: The L-type calcium channel is responsible for normal myocardial contractility and for vascular smooth muscle contractility. In contrast, T-type calcium channels are not normally present in the adult myocardium, but are prominent in conducting and pacemaking cells (so not in the ventricular myocyte)

139
Q

On an ECG where someone’s heart was being ran by the AV node, why would they not have p-waves?

A

because p-wave comes from the SA node

-HR would also be slower in this case

140
Q

valve stenosis is when

A

fail to open properly leaving a narrowed opening

141
Q

valve insufficiency is when

A

valves do not close completely; does not prevent blood from flowing backwards

142
Q

Both valve stenosis and insufficiency can be diagnosed how?

A

by listening to the heart for murmurs which are extra sounds in the cardiac cycle
-the timing of the murmur can tell you which valves might be at fault

143
Q

AV valves can prolapse, which means what? and what happens?

A

valves do not seal and the leaflets bend upwards so that they point towards the atria, which leads to insufficiency so some blood flows backwards into the atrium during systole

144
Q

isovolumetric ventricular contraction

A

has a constant volume because the valves are closed

-AV valves closed, aortic and pulmonary valves closed

145
Q

Ventricular ejection (systole)

A

blood flows out of ventricle because the ventricular pressure rises further and aortic valve pops open
-AV valve is closed because the pressure in the ventricle is larger than the pressure in the atria

146
Q

Isovolumetric ventricular relaxation (diastole)

A

AV valves closed

-aortic and pulmonary valves closed

147
Q

Ventricular filling (diastole)

A

blood flows into the ventricles

  • atria contract after depolarization
  • pressure is higher in atria
  • AV valves open
  • ventricles are relaxed and they fill
  • aortic and pulmonary valves are closed
148
Q

EDV

A

the filled volume of the ventricle prior to contraction

149
Q

ESV

A

the residual volume of blood remaining in the ventricle after ejection

PGY 412 (2 decks)

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