Peripheral Circulation and Hemodynamics Flashcards Preview

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Flashcards in Peripheral Circulation and Hemodynamics Deck (31)
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1
Q

cardiac output of a 70 kg person

A

5 L/min

2
Q

blood pressure in the aorta

A

100 mmHg

3
Q

cardiac output

A
  • 15 % brain
  • coronaries 5%
  • renal arteries 25%
  • GI tract 25%
  • skeletal muscle 25%
  • skin 5%
4
Q

afterload

A
  • 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
Q

advantages of a parallel system

A
  1. overall resistance reduced (afterload reduced)
  2. all organs receive the same “oxygenated” blood - no leftovers!
  3. common perfusion pressure
6
Q

mean blood pressure in pulmonary arteries

A

15 mmHg

7
Q

pressure of oxygenated blood entering left ventricle

A

2-5 mmHg

8
Q

the distribution of blood volume in the peripheral circulation

A
  • 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
Q

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

A
  • 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
Q

the distribution of blood pressure in the pulmonary circulation

A
  • 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
Q

determinants of blood flow

A

•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
Q

blood flow through a blood vessel

A
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
Q

vascular resistance

A
R = 8nl/π r4
•n = fluid viscosity
•l = tube length
•r = tube radius
14
Q

Pouseille’s Law

A
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
Q

laminar flow

A
  • smooth, streamlined flow

* more efficient

16
Q

turbulent flow

A
  • flow streamlines mix due to irregularities in the vessel wall
  • wastes energy
17
Q

murmurs

A
  • noises caused by turbulent flow

* carotid bruit is an example (heard >40%, <90%)

18
Q

vascular compliance

A

•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
Q

blood pressure in the venules and veins

A

10mmHg

20
Q

blood pressure in the venae cavae

A

5 mmHg

21
Q

blood pressure in the right atrium

A

0-2 mmHg

22
Q

peripheral vs pulmonary blood pressures

A
  • arranged in a series

* the entire cardiac output flows through both the peripheral and pulmonary circulations

23
Q

blood pressure in the large arteries

A

100 mmHg

24
Q

blood pressure in the arterioles

A

50 mmHg

25
Q

blood pressure in the capillaries

A

20 mmHg

26
Q

blood pressure in the pulmonary artery

A

15 mmHg

27
Q

blood pressure in the pulmonary capillaries

A

10 mmHg

28
Q

blood pressure in the pulmonary veins

A

8 mmHg

29
Q

blood pressure in the left atrium

A

2-5 mmHg

30
Q

vascular elasticity

A
  • ability to spring back

* arteries

31
Q

preload

A

•LVEDV