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Flashcards in Cardiovascular System Design Deck (26)
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are arterioles or venous blood circulation low pressure or high pressure?

arteries: high pressure (delivery)
venous: low pressure (retrieval)


percentages of blood in circulatory system

systemic circulation: 84%
-venous vessels >50%
heart: 7%
pulmonary vessels: 9%


what are vessels lined with?

continguous sheet of endothelial cells, including heart chambers and valve leaflets


blood flow through heart

Vena Cavae --> right atrium --> tricuspid valve --> right ventricle --> pulmonary valve --> lungs --> left atrium --> mitral/tricuspid valve --> left ventricle --> aortic valve


5 requirements for effective cardiac function (ventricular pumping)

1. synchronized contractions of individual cardiac cells at regular intervals
2. valves must open fully
3. valves must not be leaky
4. muscle contractions must be forceful
5. ventricles must fill adequately during diastole


equation for cardiac output (CO)

CO = SV * HR
(typical CO is 5 L/min; SV = mL, HR = beats/minute)


major determinants of stroke volume

ventricular preload (length of muscle at onset of contraction)
ventricular afterload (tension of muscle during contraction)
myocardial contractility


what effect will sleep and moderate changes in temperature have on cardiac output?

no change


what effect with anxiety/excitement, eating, exercise, high temperature, pregnancy, and epinephrine have on cardiac output?

-anxiety/excitement: 50-100%
-eating: 30%
-exercise: up to 700%


what effect will sitting/standing from lying position, rapid arrhythmias, and heart disease have on cardiac output?

-sitting/standing from lying position: 20-30%


Starling's Law

the larger the ventricular end-diastolic volume (cardiac filling in diastole), the larger the stroke volume


what does arteriolar vasoconstriction lead to?

increase in peripheral resistance


what does venous vasoconstriction lead to?

reduced venous volume and increased cardiac output (via Starling's Law)


4 main variables of flow throughout circulation

1. flow velocity (slowest in capillaries)
2. pressure (steadily decreases from arteries to veins)
3. resistance (peaks at arterioles, then tapers)
4. volume (highest in venules/veins)


mean arterial pressure and equation

average pressure over entire cardiac cycle
-MAP = DP + 1/3 (SP - DP) = DP + (1/3)(DP) = CO x TPR = HR x SV x TPR


pulse pressure

difference between systolic and diastolic pressures
PP = SP - DP = SV / compliance


systolic pressure

peak arterial pressure reached during ejection of blood by heart


diastolic pressure

lowest arterial pressure when heart is relaxed and filling with blood


dichrotic notch

also incisura: small dip caused by backfilling of aortic valve as it closes


auscultatory method to measure BP

use of external blood pressure cuff
-initially no blood flow, but as cuff pressure lowered, flow is restored and pulsatile pressure changes cause detectable turbulence
-when below diastolic, flow returned to laminar and silent


direct method to measure BP (arterial and venous)

arterial catheter: retrograde (against flow) for arteries, aorta, and left ventricle
venous catheter: antegrade (with flow) for veins, right atrium, and right ventricle
NOT possible to measure pulmonary venous and left atrial pressures directly, so need pulmonary capillary wedge pressure


pulmonary artery catheterization

catheter passed from systemic vein thru right heart into pulmonary artery
-lumen open at distal end
-balloon inflated and pressure falls downstream
-vascular pressure equilibrates beyond balloon, and wedge pressure at catheter tip is measure of pulmonary venous and left atrium
-approximates left ventricular end-diastolic pressure


where do changes in MAP come from?

changes in CO or TPR (total peripheral resistance)


what is average PP, SV, and compliance in resting young adult

pulse pressure = 40 mmHg
stroke volume = 80 mL
compliance = 2 mL/mmHg


short term control of MAP

altering peripheral resistance counteracts most moment-to-moment fluctuations
-vasomotor activity regulates vasomotor tone and peripheral resistance
-usually countered via baroreceptor reflex, altering CO and peripheral resistance
-both normally and neurally


long term control of MAP

altering blood volume via kidneys

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