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112 Cards in this Set
- Front
- Back
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heart pumps |
4-6 L/min |
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miles of blood vessels |
100,000 miles of blood vessels |
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total blood volume |
3 L |
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percent of blood in systemic and pulmonary circulation |
84% systemic circulation 16% pulmonary circulation |
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percent of blood in heart |
7% |
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percent of blood in arteries |
13% |
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percent of blood in arterioles and capillaries |
7% |
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percent of blood in veins, venules and venous sinuses |
64% |
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biggest diameter |
6x10^4 cm (capillaries) |
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smallest diameter |
0.5 cm (small veins and small arteries) |
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biggest area |
2500 cm2 (capillaries) |
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smallest area |
2.5 cm2 (aorta) |
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highest pressure |
100 mmHg (aorta and small arteries) |
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smallest pressure |
2 mmHg (venae cavae) |
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highest velocity |
33 cm/s (aorta) |
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lowest velocity |
0.03 cm/s (capillaries) |
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basic principles of circulatory function |
1. the cardiac output is mainly controlled by the sum of all the local tissue flows 2. in general, the arterial pressure is controlled independently of either local blood flow control or cardiac output control 3. the rate of blood flow to each tissue of the body is almost always precisely controlled in relation to the tissue needs (local blood flow and nervous control) |
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regulation of arterial pressure by nervous control |
-force of heart pumping -generalized constriction of most arterioles -regulation of blood volume by the kidneys -release of blood by the blood reservoirs |
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blood flow through a vessel is determined by |
vascular resistance pressure gradient |
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pressure difference of blood between 2 ends |
pressure gradient |
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impediment of blood flow through the vessels |
vascular resistance |
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Ohm's Law |
F = P2-P1/R |
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quantity of blood that passes a given point in the circulation in a given period of time |
blood flow |
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units of blood flow |
mL/min L/min mL/sec |
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overall cardiac output |
5,000 mL/min |
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measures flow of blood |
flowmeter |
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streamlined flow of blood when it flows steadily through smooth blood vessels
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laminar flow |
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formation of eddy currents when blood flow becomes too great, passes an obstruction or passes a rough surface |
turbulent flow |
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relationship of turbulence and resistance to flow |
directly proportional |
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force exerted by blood against any unit area of the vessel wall |
blood pressure |
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units of blood pressure |
mmHg occasionally cmH2O |
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mmHg and cmH2O conversion factor |
1 mmHg = 1.36 cmH2O |
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impediment to blood flow |
resistance to blood flow |
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unit of resistance to blood flow
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peripheral resistance unit |
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PRU formula |
PRU = mmHg/mL/sec |
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total peripheral resistance |
in adult, the pressure difference between arteries and veins is 100 mmHg with cardiac output of 100 mL/sec so the TPR is 1 PRU |
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vasoconstriction resistance |
increase by 4 PRU |
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vasodilation resistance |
decrease by 0.2 PRU |
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total pulmonary resistance |
14 mmHg/100 mL/sec= 0.14 PRU |
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measure of the blood flow through a vessel for a given pressure difference |
conductance of blood vessel |
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exact reciprocal of resistance |
conductance of blood vessel |
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conductance relationship with diameter of the vessel |
conductance increases in proportion to the fourth power of the diameter of the vessel |
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poiseuille's law |
F = (pi)(P2-P1)r^4/8nL where r = radius of vessel n = blood viscosity L = length of vessel |
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relationship between viscosity and blood flow |
inversely proportional |
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viscosity of blood |
3x more viscous than water |
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cell volume/blood volume |
hematocrit |
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male hct |
42 |
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female hct |
38 |
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Hct and viscosity with polycythemia |
hct 60-70 viscosity x10 |
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pressure and blood flow relationship |
directly proportional |
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why does increase in pressure increase blood flow? |
increase in pressure distends the vessels which decreases resistance causing additional increase in blood flow |
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sympathetic stimulation |
vasoconstriction |
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sympathetic inhibition |
vasodilation |
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fractional increase in volume for each mmHg rise in pressure |
distensibility |
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vascular distensibility formula |
vascular distensibility = increase in volume/(increase in pressure)(original volume) |
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total quantity of blood that can be stored in a given portion of the circulation |
compliance |
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vascular compliance formula |
vascular compliance = increase in volume/increase in pressure |
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compliance formula with D and V |
C = DV |
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why are veins more compliant than arteries |
distensibility of veins is 8x and volume is 3x greater than arteries so Cveins = 24x(Carteries) |
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volume of arterial system |
750 mL |
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volume of venous system |
2500-3500 mL |
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causes an increase in vascular tone and increase in pressure |
sympathetic stimulation |
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results in a decrease in arterial and venous volumes and shift of blood into the heart |
vasoconstriction |
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principle mechanism to increase cardiac stroke volume and cardiac output |
shift of blood into the heart |
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important during hemorrhage; loss of up to 25% of blood doesnt affect circulation |
sympathetic control |
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pressure at height of each pulse |
systolic pressure (120 mmHg) |
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pressure at lowest point of each pulse |
diastolic pressure (80 mmHg) |
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difference between systolic and diastolic pressures |
pulse pressure (40 mmHg) |
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2 major factors affecting pulse pressure |
1. Carterial (total distensibility) 2. Vstroke (stroke volume output) |
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increase in SVO results in |
increase in SP and DP and increase in PP |
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decrease in total distensibility results in |
increase in PP |
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pulse pressure formula with Carterial and SVO |
PP = Vstroke/Carterial |
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describe the normal central aortic pulse wave |
the normal central aortic pulse wave is characterized by a fairly rapid rise to a somewhat rounded peak. the less steep descending limb is interrupted by a sharp downward deflection conincident with the AV closure called the incisura |
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abnormal pressure pulse contour |
arteriosclerosis aortic stenosis patent ductus arteriosus |
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causes noncompliance |
arteriosclerosis |
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effect of arteriosclerosis to pulse pressure |
increase |
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decreases stroke volume due to decreased valve opening; hardening of aortic valves |
aortic stenosis |
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effect of aortic stenosis to pulse pressure |
decrease |
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causes loss of significant fraction of stroke volume to the pulmonary arterty |
patent ductus arteriosus |
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effect of patent ductus arteriosus to diastolic pressure |
decrease |
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flappy/leaky/absent aortic valves |
aortic regurgitation |
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effects of aortic regurgitation |
significant fall of diastolic pressure and no incisura |
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relationship between compliance and velocity of PP transmission |
inversely proportional |
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velocity of pp transmission of aorta |
3-5 m/s |
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velocity of pp transmission of large aortic branches |
7-10 m/s |
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velocity of pp transmission of small arteries |
15-35 m/s |
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causes of damping |
1. resistance to blood movement 2. compliance of the vessels |
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degree of damping? |
the degree of damping is almost directly proportional to the product of resistance and compliance |
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inflate the cuff above systolic pressure and then slowly release the pressure while listening to the Korotkoff sounds of the brachial artery |
auscultatory method |
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changes in arterial pressures with age |
-in kidneys after the age of 50 years -atherosclerosis beyond 60 years |
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hardening of arteries |
atherosclerosis |
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normal right atrial pressure |
0 mmHg |
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when does RAP reach -5 mmHg |
after vigorous exercise |
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when does RAP reach 20-30 mmHg |
-serious heart failure -massive blood transfusions |
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factors that increase venous return |
1. increased blood volume 2. increased large vessel tone -> increased peripheral venous pressures 3. dilation of arterioles -> decreased peripheral resistance -> increased blood flow |
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venous pressure in large veins |
almost 0 (especially when distended) |
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peripheral venous pressure when lying down |
4-6 mmHg |
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venous pressure in the lower limbs must increase to overcome intra-abdominal pressure especially in ..? |
pregnancy ascites presence of large tumors |
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intra-abdominal pressure |
6 mmHg (can increase to 15-30 mmHg) |
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intrathoracic perssure |
-4 mmHg |
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results from weight of water |
gravitational or hydrostatic pressure |
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what happens when standing still |
-feet venous pressure is 90 mmHg -neck veins are collapsed -dural sinuses contained to noncollapsible cavity, hence negative pressure |
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arterial pressure at heart level and feet |
100 mmHg heart level 190 mmHg feet |
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serve as pumps that return blood towards the heart |
limb muscles |
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pressure change from standing still to walking |
90 mmHg (standing) to 20 mmHg (walking) |
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also helps in venous return of blood |
negative pressure in the thoracic cavity during inspiration |
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process to edema |
prolonged increase in VP---venous valve incompetence---VP increase due to failure of pumps---varicose veins---increased venous and capillary pressures---edema of legs |
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sympathetic stimulation increase chain |
increased sympathetic stimulation of veins---increased venous return to heart---increased cardiac output by 7x |
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blood reservoir that releases 100 mL of blood |
spleen |
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blood reservoir that releases several hundreds of blood |
liver |
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blood reservoir that can release as much as 300 mL? |
large abdominal veins |
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blood reservoirs |
liver spleen large abdominal veins venous plexuses under the skin |
