3.3 Circulation Flashcards Preview

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Flashcards in 3.3 Circulation Deck (50):
1

Hemodynamics

Circulation of blood in the vasculature

2

What matters in maintaining blood flow?

Hydrostatic pressure and Mean arterial pressure

3

Hydrostatic pressure

Fluid physics, you need a driving force causing liquid blood to flow through the vascular tubing in all the tissues

4

Mean Arterial Pressure

"Average blood pressure"
Essential to maintaining adequate volume of blood circulation and perfusion of all tissues

5

MAP =

[(2 x diastolic) + systolic] / 3

6

Normal MAP

80-90 mm Hg

7

Why is normal MAP closer to diastolic?

Because we spend so much more time in diastole

8

MAP =

CO x SVR

9

Systemic Vascular Resistance

Pressure component of MAP that is dependent on the vasculature
(controlled through vasoconstriction and vasodilation)

10

SVR increases / decreases depending on..

1) Volume of entire vasculature
2) Blood Viscosity

11

Volume is a function of

-Total length of vascular system
-Diameter of vessels in the system

12

Larger diameter of vessels would lead to...

Lower resistance, lower back pressure

13

Blood viscosity

Thickness of the blood

14

What are vasculature lined with? (inside)

Endothelium comprised of endothelial cells

15

Elastic arteries

Largest arteries, lots of elastic tissue

16

What do elastic arteries do?

-Stretch during ventricular systole
-Recoil during diastole

17

What underlie the blood pressure measurement?

Stretch and recoil of elastic arteries

18

How does elasticity relate to high blood pressure in diabetics?

Too much sugar in blood hardens elastic arteries, blood going through never gets "tamped down" by elasticity of arteries

19

Muscular arteries

Medium sized arteries that branch from aorta, more smooth muscle than elastic tissue

20

Arterioles

Small arteries with vascular smooth muscle, involuntary yet highly regulatable

21

What do resistance vessels do?

They play a key role in rapidly changing SVR to respond to local tissue metabolic demands and the autonomic nervous system

22

What must larger arteries and arterioles do?

Reduce pulses of pressure and fast moving blood before entering capillaries

23

How does blood enter capillaries?

Smooth, laminar (even, no systole or diastole) flow

24

Capillaries

Single endothelial layer thick
Site of "capillary exchange" by diffusion (and pinocytosis)

25

Blood moves slowest in capillaries due to..

1) Arterioles
2) Massive "total cross sectional area'

26

Veins

-Lowest pressure
-One way valves
-Walls contain minimal vascular smooth muscle (but can still constrict
-Highly compliant

27

Compliance

"Stretchiness" in the walls of vessels.. small change in pressure leads to large change in volume

28

At rest, where is a majority (64%) of our blood?

Systemic veins and venues!

29

3 ways to mobilize the blood out of storage (veins) during exercise

1) Venoconstriction
2) Muscle activity
3) Valves

30

Venoconstriction (during exercise)

Sympathetic tone --> Contraction of smooth muscle surrounding veins --> decreases venous increases return of blood to the heart

31

What does an increase in return of blood to the heart cause and what is it due to?

Increases CO
Frank-Starling Law

32

Two components of muscle capacity in venous return

a)Contraction and movement of skeletal muscles
b) Respiratory pump

33

How do valves in the vein help during exercise?

Allow for no back flow of blood

34

Capillary exchange

How molecules move from blood to interstitial fluid and ultimately into cells

35

Primary and secondary routes of capillary exchange

Diffusion
Pinocytosis

36

Filtration

Water and some solutes from blood to interstitial space

37

Reabsorption

Water and some solutes from interstitial space back into blood

38

Forces driving filtration and reabsorption

1) Hydrostatic pressure
2) Osmosis

39

What is the hydrostatic pressure in capillary coming in and going out?

35 mm Hg
16 mm Hg

40

What is the hydrostatic pressure in the interstitial fluid?

ZERO

41

Osmosis can also be called...

Osmotic pressure of Colloidal osmotic pressure

42

What exerts vital osmotic pressure to counteract hydrostatic pressure?

Plasma proteins (liver albumin)

43

Does the interstitial space have a high or low osmolarity?

Very low, drives the liquid back into the "salty" blood

44

What is the net filtration when combining filtration and reabsorption?

14 + (-5) = 9mmHg net filtration OUT

45

What does the blood hydrostatic pressure do going through a capillary?

Plummets

46

What does the blood colloidal osmotic pressure do going through a capillary?

Holds steady at 26 mmHg between beginning and end of capillary

47

Interstitial COP is..

At a constant 5 mmHg

48

What happens to the extra "net filtrate"?

Picked up and moved by the lymphatic system and eventually returned to circulatory system

49

Lymphatic capillaries

Origin of lymph, low protein liquid filtrate that leaves blood capillaries and becomes interstitial fluid

50

Key features of lymphatic capillaries

"One-way door"
Anchoring filaments that are responsive to interstitial fluid accumulation