Peripheral Circulation and Hemodynamics Flashcards Preview

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Flashcards in Peripheral Circulation and Hemodynamics Deck (31)
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1

cardiac output of a 70 kg person

5 L/min

2

blood pressure in the aorta

100 mmHg

3

cardiac output

•15 % brain
•coronaries 5%
•renal arteries 25%
•GI tract 25%
•skeletal muscle 25%
•skin 5%

4

afterload

•overall resistance of the vasculature to blood flow
•affects the amount of work required by the heart
•important to keep it at a minimum

5

advantages of a parallel system

1. overall resistance reduced (afterload reduced)
2. all organs receive the same "oxygenated" blood - no leftovers!
3. common perfusion pressure

6

mean blood pressure in pulmonary arteries

15 mmHg

7

pressure of oxygenated blood entering left ventricle

2-5 mmHg

8

the distribution of blood volume in the peripheral circulation

•very little in arterioles and capillaries
•most found in veins and venules
•venous circulation is sometimes referred to as the "reservoir" portion of the vasculature
•vasoconstriction can lead to enhanced venous return to the right heart

9

the distribution of blood pressure in the peripheral (systemic) system

•blood flows from high to low pressure, dictated by pressure gradient
•decreases little in the aorta and large arteries, falls substantially as the blood traverses the arterioles ("resistance" vessels) - this is where blood flow to the organs is controlled
•total blood pressure difference is 100-0 mmHg

10

the distribution of blood pressure in the pulmonary circulation

•15-2 mmHg
•takes much less pressure to be generated by the right heart, or right ventricle to move the same amount of blood through the pulmonary circulation than it takes the left ventricle to push blood through the peripheral circulation

11

determinants of blood flow

•homeostasis (maintenance of the internal mileau) requires the constant delivery of nutrients and signaling molecules to the cells of the body and removal of waste products ---BLOOD FLOW!
-blood flow through a blood vessel - pressure gradient and resistance
-vascular resistance - pressure gradient, radius, viscosity
(these first two go hand in hand)
-laminar flow/turbulent flow

12

blood flow through a blood vessel

Q=(P1-P2)/R
•Q = flow
•P1 = blood pressure at input of vessel
•P2 = blood pressure at outflow of vessel
•R = resistance to flow

13

vascular resistance

R = 8nl/π r4
•n = fluid viscosity
•l = tube length
•r = tube radius

14

Pouseille's Law

Q=(P1-P2)/R
•Q = flow
•P1 = blood pressure at input of vessel
•P2 = blood pressure at outflow of vessel
•R = resistance to flow

R = 8nl/π r4
•n = fluid viscosity
•l = tube length
•r = tube radius

combine:

Q = (P1-P2) πr4/8nl

Volumetric blood flow depends on pressure gradient, radius, and the viscosity of the fluid

15

laminar flow

•smooth, streamlined flow
•more efficient

16

turbulent flow

•flow streamlines mix due to irregularities in the vessel wall
•wastes energy

17

murmurs

•noises caused by turbulent flow
•carotid bruit is an example (heard >40%, <90%)

18

vascular compliance

•a measure of the distensibilty of a vessel

C = ∆V/ ∆P
•C = compliance
•V = volume
•P = pressure

•vein has the greatest compliance and and aged artery has the lowest

19

blood pressure in the venules and veins

10mmHg

20

blood pressure in the venae cavae

5 mmHg

21

blood pressure in the right atrium

0-2 mmHg

22

peripheral vs pulmonary blood pressures

•arranged in a series
•the entire cardiac output flows through both the peripheral and pulmonary circulations

23

blood pressure in the large arteries

100 mmHg

24

blood pressure in the arterioles

50 mmHg

25

blood pressure in the capillaries

20 mmHg

26

blood pressure in the pulmonary artery

15 mmHg

27

blood pressure in the pulmonary capillaries

10 mmHg

28

blood pressure in the pulmonary veins

8 mmHg

29

blood pressure in the left atrium

2-5 mmHg

30

vascular elasticity

•ability to spring back
•arteries