Capillaries

Question 0

Capillary Structure

Answer 0

• single layer
• extensively branched
• low blood volume (large SA)
• slow velocity

Question 1

Capillary Function

Answer 1

Sites for exchange

Question 2

Capillary Structure is

Answer 2

ideal for exchange

Question 3

Capillary density

Answer 3

tissue dependent

• skeletal m. and heart are capillary dense
• cartilage/fat = low capillary density

Question 4

Capillaries also do..

Answer 4

nutritional/non-nutritional flow

heat removal

Question 5

Capillary wall structure

Answer 5

consists of endothelium & basement membrane. thin walls & small lumen diamenter

optimal for exchange

Question 6

Capillary permeability

Answer 6

varies depending on organ/tissue supplied

Question 7

Types of capillary permeability

Answer 7

1. Continuous
2. Fenestrated
3. Sinusoidal

Question 8

Continuous capillary location

Answer 8

brain (NO pores)
muscle
adipose
lymph nodes

Question 9

Fenestrated capillary location

Answer 9

kidney
intestines
colon
exocrine glands

Question 10

Sinusoidal capillary location

Answer 10

liver
spleen
pituitary gland
bone marrow

Question 11

Capillary blood flow controlled by…

Answer 11

1. Arterioles
2. Metarterioles
3. Precapillary sphincters

Question 12

Metarterioles

Answer 12

can bypass system if capillary bed doesn’t need blood OR permit it to flow

Question 13

precapillary sphincters

Answer 13

• appear to be innervated sympathetcially
• high degree of myogenic tone
• sensitive to metabolic factors

Question 14

Transcapillary exchange

Answer 14

processes of solvent & solute movement across capillary walls

Question 15

Types of transcapillary exchange

Answer 15

1. Diffusion
2. Filtration/Absorption
3. Pinocytosis

Question 16

Diffusion

Answer 16

movement from high to low concentration

Question 17

types of transcapillary exchange diffusion

Answer 17

• transcellular

- paracellular

Question 18

FIltration/Absorption (bulk flow)

Answer 18

volume of protein-free fluid filtered out of capillary into ISF or absorbed into capillary from ISF

Question 19

Purpose of Filtration/Absorption transcapillary exchange

Answer 19

keep plasma volume at normal level

Question 20

Pinocytosis

Answer 20

vesicular transport

least utilized mechanism of trancapillary exchange

Question 21

Things affecting transcapillary exchange

Answer 21

1. Permeability
2. Surface area
3. Concentration gradient

Question 22

Permeability coefficient

Answer 22

decreases as molecular radius increases

Question 23

Lipid soluble substance diffuse by

Answer 23

transcellular route

Question 24

Small water soluble solutes diffuse by

Answer 24

paracellular route

Question 25

Capillary exchange of water occurs as

Answer 25

bulk flow | important in ECF distribution

Question 26

Driving forces for fluid movement

Answer 26

1. Hydrostatic pressures | 2. Colloid osmotic or oncotic pressures

Question 27

hydrostatic pressures

Answer 27

exerted by fluid across capillary wall

Question 28

colloid osmotic/oncotic pressure

Answer 28

exerted by proteins across capillary wall

Question 29

Fluid filtration/reabsorption dictated by

Answer 29

hydrostatic & oncotic pressures

Question 30

Capillary pressure

Answer 30

pushes fluid out of capillary to decrease total plamsa volume

Question 31

interstitial fluid pressure

Answer 31

pushes fluid into capillaries

Question 32

plasma colloid osmotic pressure

Answer 32

pulls H2O into capillary via osmosis

Question 33

Interstitial fluid colloid osmotic pressure

Answer 33

pulls H2O out of vascular bed

Question 34

movement depends on

Answer 34

which pressure gradient is the highest

Question 35

What determines if fluid leaves capillary beds?

Answer 35

hydrostatic pressure gradient is higher than colloid osmotic pressure gradient

Question 36

What determines if fluid enters vascular space?

Answer 36

Hydrostatic pressure gradient is less than colloid osmotic pressure gradient

Question 37

Absorption in capillary beds

Answer 37

occurs when capillary beds are in series because 2nd capillary bed has decreased hydrostatic pressure due to loss of fluid in 1st capillary

Question 38

Hemodynamic forces affect

Answer 38

capillary hydrostatic pressure & direction/magnitude of transcapillary fluid movement

Question 39

Hemodynamic forces do

Answer 39

^ arterial or venous pressure ^ arterial resistance ^ venous resistance

Question 40

arterial resistance is

Answer 40

a principal determinant of capillary hydrostatic pressure

Question 41

Pinocytosis

Answer 41

vesicular transport of MACROMOLECULES across capillary wall

Question 42

Caveolae

Answer 42

- coated pits in capillary wall | - may form channels through cell for transport across membrane

Question 43

Limits to pinocytosis

Answer 43

molecular radius | -molecules must fit into caveolae

Question 44

Another name for pinocytosis

Answer 44

Transcytosis

Question 45

High metabolic demand induces

Answer 45

capillary recruitment

Question 46

When metabolic demand increases

Answer 46

- more capillaries open | - smaller tissue area is supplied per capillary

Question 47

Capillaries serve __ amount of tissue

Answer 47

can be larger or smaller depending on metabolic demand

Question 48

Capillary recruitment

Answer 48

- alternating areas of tissues have open/closed capillaries constantly. - even under resting conditions, capillaries alternate opening and closing

Question 49

Better blood supply given

Answer 49

when more capillaries are open

Question 50

Molecular transport limited by..

Answer 50

blood flow to the area or diffusion from capillary to tissue/cells

Question 51

Limitations in molecule transport can be overcome by

Answer 51

increasing capillary density