Midterm 1 - Blood Volume Microcirculation and Fluid Exchange

Question 1

what percentage of blood do capillaries contain

Answer 1

about 5%

Question 2

what are capillaries the site of

Answer 2

water-nutrients-wastes-gases exchange with interstitial fluid and tissues

Question 3

how large are capillaries in diameter

Answer 3

7-8 um

Question 4

how long are capillaries

Answer 4

0.5 mm

Question 5

what are red blood cells in diameter

Answer 5

approx. 7.5 um

Question 6

what are capillaries made of

Answer 6

a single layer of endothelial cells

Question 7

what are capillaries formed in

Answer 7

dense netowkrs

Question 8

how close is each cell of a tissue to a capillary

Answer 8

within 100 um

Question 9

where do capillaries receive blood from

Answer 9

smallest arterioles and metarterioles

Question 10

metarterioles

Answer 10

connection between arteriole and capillaries network

Question 11

what does the density of capillaries vary depending on

Answer 11

the metabolic activity of the tissue

Question 12

what do met arterioles possess

Answer 12

rings of smooth muscle tissue that can open and close on demand

Question 13

what are met arterioles doing during exercise

Answer 13

all open

Question 14

what is the consequence of the small diameter

Answer 14

a very slow flow

Question 15

what is resistance reduced by in capillaries

Answer 15

the extent of the parallel ramifications

Question 16

what does trans capillary diffusion depend on

Answer 16

capillary type and substance properties

Question 17

what does transcapillary diffusion follow

Answer 17

gradient between blood and interstitial fluid

Question 18

what do most capillaries have that allow transfer of water and lipid-insoluble molecules

Answer 18

pores or clefts

Question 19

what do the size and number of pores in a capillary depend on

Answer 19

the tissue

Question 20

what type of substances exchange freely across cell membrane

Answer 20

lipid soluble (O2 and CO2)

Question 21

what capillaries are fenestrated

Answer 21

intestine
liver
kidney

Question 22

what does it mean for capillaries to be fenestrated

Answer 22

vesicles fuse to form large gaps across endothelial cell membrane

Question 23

what do fenestrated capillaries allow

Answer 23

water and water soluble macromolecules to pass

Question 24

what is bulk flow

Answer 24

mass movement of water and dissolves substances through water pores

Question 25

where does bulk flow take place

Answer 25

across the capillary walls

Question 26

where is bulk flow filtered

Answer 26

towards interstitial fluid (out of blood compartment)

Question 27

where is bulk flow absorbed

Answer 27

towards the intravascular fluid (blood)

Question 28

what does bulk flow maintain

Answer 28

fluid balance between intravascular and interstitial fluid

Question 29

what is bulk flow dependent on

Answer 29

pressure gradients permeability of vessel size of diffusion surface blood flow

Question 30

what pressure gradients is bulk flow dependent on

Answer 30

hydrostatic and osmotic

Question 31

hydrostatic pressure

Answer 31

filtration pressure - BP inside blood vessels pushes fluid out

Question 32

process of hydrostatic pressure

Answer 32

pressure from heart --> arterioles --> capillaries since pressure in interstitial fluid is close to 0, pushes fluid out of vessel

Question 33

what is colloid osmotic pressure (oncotic)

Answer 33

counter balances hydrostatic pressure due to large proteins in that stay in vessel, fluid is reabsorbed

Question 34

what are starling forces

Answer 34

net movement of fluid depends on balance between filtration (hydrostatic) and osmotic (oncotic) pressures

Question 35

what pushes fluid out

Answer 35

hydrostatic pressure difference

Question 36

what pushes fluid back in

Answer 36

osmotic pressure difference

Question 37

what remains constant along capillary length

Answer 37

osmotic pressure difference

Question 38

where along the capillary is hydrostatic stronger

Answer 38

in the first portion

Question 39

where along the capillary does hydrostatic decrease

Answer 39

toward the end - less fluid out, and if hydrostatic < osmotic, fluid moves in

Question 40

what is the net effect of fluid exchange

Answer 40

generally accumulation of fluid into interstitial tissue

Question 41

what picks up fluid

Answer 41

lymphatic system

Question 42

what is lymphatic drainage

Answer 42

the draining of fluid to large veins

Question 43

what happens to fluid that remains in blood

Answer 43

collects into venues and goes back to heart

Question 44

what occurs if the lymphatic system cannot keep up with fluid exchange

Answer 44

edema formation (filtration exceeds capacity)

Question 45

what is the physiological significance of diffusion

Answer 45

nutrient and gas exchange

Question 46

what is the physiological significance of bulk flow

Answer 46

stabilize blood volume using interstitial fluid as a buffer

Question 47

physiological significance with blood loss

Answer 47

decrease in pressure --> decrease in hydrostatic = fluid enters back

Question 48

physiological significance of excess fluid intake

Answer 48

increase in pressure --> increase in hydrostatic --> fluid accumulates in interstitial

Question 49

physiological significance of low protein in plasma

Answer 49

decrease in ostmotic --> fluid out

Question 50

physiological significance of high protein in plasma

Answer 50

increase in osmotic --> fluid in

Question 51

what is an edema

Answer 51

abnormal accumulation of interstitial fluid

Question 52

what are the 4 mechanisms responsible for edemas

Answer 52

increase in hydrostatic pressure in blood vessels increase in interstitial protein concentration decrease in oncotic pressure obstruction of lymphatic vessels

Question 53

what can be an effector of increased hydrostatic pressure in blood vessels

Answer 53

increase arterial pressure (hypertension) increased venous pressure (right sided heart failure)

Question 54

what can be an effector of increased interstitial protein concentration

Answer 54

inflammation of capillaries, become leaky

Question 55

what can be an effector of decreased oncotic pressure

Answer 55

loss of proteins (GI disease) liver disease poor diet

Question 56

where do edemas often occur

Answer 56

in abdominal cavity legs due to gravity