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Physiology > Capillaries > Flashcards

Flashcards in Capillaries Deck (65):
1

What is the function of the capillaries?

Exchange fluid, nutrients, hormones etc

2

What is the rate of exchange of nutrients in capillaries related to?

Bulk flow

3

What features of the capillaries contribute to its function?

Thin walls with pores

4

What modifies what goes through capillaries?

Size of the pores

5

Can lipid soluble substances get through capillaries via diffusion? Can proteins? Water soluble ions?

Yes for lipid
No for proteins or water solubles

6

What are the spaces between the capillaries?

Intracellular clefts and caveolae

7

What covers the tissue side of the capillaries?

BM

8

What is vasomotion?

intermittent blood flow through capillaries d/t contraction of metarterioles and precapillary sphincters

9

What structures regulate blood flow through capillaries? What are those regulated by?

Through precapillary sphincters

Regulated by tissue oxygen usage

10

Is there smooth muscle in capillaries? What is the consequence of this?

No, means that can close capillaries completely

11

If you increase surface area (as in the increase CSA for capillaries) what happens to velocity?

Decreases velocity

12

Why can't capillaries contract or relax?

No smooth muscle

13

Blood flow through capillaries depends on what?

What can get through upstream via sphincters, arterioles etc

14

What is the main metabolic regulator of skeletal muscle? Lesser regulators?

pO2

pCO2, pH, flow

15

What is the main metabolic regulator of the brain? Lesser regulators?

pCO2

pO2, adenosine

16

What is the main metabolic regulator of the heart? Lesser regulators?

[adenosine]

pO2, pCO2, pH

17

How does epinephrine control blood flow through capillaries?

Constricts and dilates

18

How does Norepinephrine control blood flow through capillaries?

Constricts

19

How does dopamine control blood flow through capillaries?

Constricts and dilates

20

How does histamine control blood flow through capillaries?

dilates

21

How does acetylcholine control blood flow through capillaries?

Dilates

22

How does angiotensin II control blood flow through capillaries?

Dilates

23

How do Kinins control blood flow through capillaries?

Dilates

24

How does ADH/vasopressin control blood flow through capillaries?

Constricts

25

How does VIP control blood flow through capillaries?

Dilates

26

How do hormones have opposite effects on the same capillary bed?

Different receptors

27

How does adenosine control blood flow through capillaries?

Constricts, dilates

28

How does hypoxemia control blood flow through capillaries?

Dilates

29

How does [H+] and [K+] control blood flow through capillaries?

Dilates

30

How does hypercapnia control blood flow through capillaries?

Dilates

31

How do Kreb cycle intermediaes control blood flow through capillaries?

Dilates

32

How does endothelin control blood flow through capillaries?

Constricts

33

How does EDRF (NO) control blood flow through capillaries?

dilates

34

What determines that rate of exchange of a chemical through a capillary bed?

Solubility in lipids or water

Molecular size

35

If a chemical is lipid soluble, how does it pass through capillaries?

Direct diffusion

36

If a chemical is water soluble, how does is pass through the capillary bed?

Through pore/clefts

37

How does molecular size relate to the rate of passage through capillaries?

Inversely related

38

What is colloid osmotic pressure?

The force exerted by molecules inside a fluid on the wall that contain it

39

What is capillary hydrostatic pressure (Pc)? How does it relate to flow?

Fluid pressure within capillaries that tends to move fluid out

Directly related to flow

40

The hydrostatic pressure of tissues is (high/low) compared to capillaires? How does this affect permeability?

Low

Increases permeability

41

A tightly encapsulated tissue (like the kidney) causes what?

Increases Pif, to move fluid back into tissue

42

Oncotic pressure within capillaries tend to move fluid (in/out).

In

43

Proteins in the interstitium will move fluid (in/out) of the capillaries?

Out

44

What is the equation for net pressure?

Pc - Pif -(pi)c + (pi)if

45

If net fluid pressure is greater than 0, where will fluid move?

out of the capillary

46

If net fluid pressure is less than 0, where will fluid move?

Into the capillary

47

How do water soluble substances get through the capillaries?

Through the pores in the capillaries

48

How do we describe flow through capillaries (individually or as a sum/product of many?)

Sum of many capillaries

49

Where in the body is the only place dopamine will cause capillary constriction?

Kidneys

50

What is the effect of adenosine in the kidneys?

Constriction of capillary beds

51

What does reabsorption mean in terms of capillary exchange?

Reuptake into the capillary

52

What does filtration mean in terms of capillary exchange?

Removal from the blood

53

How permeable it the liver to molecules? The brain?

Liver = highly permeable
Brain = Not so much

54

What maintains the low hydrostatic pressure in the interstitium?

Lymphatic system

55

What is the effect on interstitial hydrostatic pressure if the tissue is surrounded by a tight capsule? What is the effect that this produces on the flow of interstitial fluid (does it go back in, or does it come out faster)?

Increases it, causing fluid to move back into the capillary

56

What is oncotic pressure? What is the effect on movement of fluid into/out of capillaries?

The pressure exerted by a [C] of some molecule. This causes movement in the direction of higher [C]

57

What is the equation for the net pressure exerted on capillary fluid? What happens if this sum is greater than 0?

Pc - Pif - (pi)c + (pi)if

If this sum is >0, then net fluid movement will be out of the capillary

58

In the equation of net pressure in a capillary (Pc - Pif - (pi)c + (pi)if), which component is variable with the location in the capillary?

Pc

59

What happens if there is in an increase of Pc?

A shift of the curve, meaning that at every point in the capillary, there is a higher rate of filtration

60

What happens if there is decrease in oncotic pressure within the capillary?

Shift of the horizontal line downward, meaning that at every point in the capillary, there is a higher rate of filtration

61

What happens to Pc if we decrease resistance within the capillary (say, by opening a sphincter at the venule end of the capillary)?

Pc curve shifts down, meaning that at every point along the capillary, there is less filtration occurring

62

Which variables does the lymphatic system change, so that there is a net efflux of fluid out of the capillaries?

(pi)if and Pif (both are decreased)

63

What are the three factors mentioned in class, that can serve to increase the Pc? What will this cause?

Standing, Heart failure, venous thrombus

These all cause edema

64

What are the three factors mentioned in class, that can serve to decreased the (pi)c? What will this cause?

Nephrotic syndrome, starvation, pregnancy

Edema

65

What does inflammation of the capillary wall cause?

Edema (I think d/t increase in surface area)