Microcirculation

Question 1

Arterioles innervation

Answer 1

Sympathetic:
α1-adrenergic
β2-adrenergic

Question 2

α1-adrenergic receptors where?

Answer 2

skin

Question 3

Activation of α1-adrenergic receptors results in?

Answer 3

(contraction of VSM)
↓ diameter
↑ resistance
↓ flow

Question 4

β2-adrenergic receptors where?

Answer 4

skeletal mm

Question 5

Activation of β2-adrenergic receptors results in?

Answer 5

(relaxation of VSM)
↑ diameter
↓ resistance
↑ flow

Question 6

Other effectors of arteriole resistance

Answer 6

circulating catecholamines

Question 7

Vein/Venule wall layers

Answer 7

endothelial
elastic tissue
smooth mm
CT

Question 8

Sympathetic stim of Vein/Venule results in?

Answer 8

venoconstriction ->
↓ compliance for venous return ->
↓ unstressed vol

Question 9

Capillary perfusion depends on?

Answer 9

(not all perfused at same time)
metabolic needs of the particular tissue,
dilation/contr of precapillary sphincters

Question 10

Precapillary sphincter regulated by?

Answer 10

sympathetic innerv of smooth mm,

metabolites from tissues

Question 11

Solute/Gas Exchange across capillary wall via what kind of diffusion?

Answer 11

simple

solutes/gas can go through or between endothelial cells

Question 12

O2 and CO2 (lipid soluble) diffusion driven by?

Answer 12

Partial pressure gradient for the gas and

Surface area

Question 13

H2O, Glucose, AA (H2O soluble) diffuse via?

Answer 13

aqueous clefts between endo cells

Question 14

Proteins diffusion?

Answer 14

Too large to cross clefts,

Retained in vascular compartments

Question 15

Clefts in Brain vs Kidneys/Intestines

Answer 15

Brain: tight clefts, very little protein transfer

Kidney/Int: fenestrated clefts, some protein transfer

Question 16

Most important mechanism for fluid transfer across capillary wall is?

Answer 16

Bulk flow

Question 17

Bulk Flow driven by?

Answer 17

hydrostatic P
osmotic (oncotic) P
(Startling Pressures)

Question 18

Role of Lymphatics

Answer 18

return ISF and proteins to vascular compartments

Question 19

Location of Lymphatics

Answer 19

ISF near capillaries

Question 20

Structure of Lymphatics

Answer 20

one-way valves

smooth mm

Question 21

Flow of Lymphatics

Answer 21

capillaries -> lymph vessels -> thoracic duct -> large veins

Question 22

Startling Eqn

Answer 22

Jv = Kf [(Pc – Pi) – (πc - πi)]

Jv = fluid movement
Kf = hydraulic conductance
Pc = capillary hydrostat P
Pi = interstitial hydrostat P
πc = capillary oncotic P
πi = interstitial oncotic P

Question 23

Startling Eqn tells us?

Answer 23

direction of fluid movement (in or out of capillary)

Magnitude of fluid mvmt per hydraulic conductance (water permeability) of wall

Question 24

Filtration is?

Answer 24

net mvmt OUT of capillary into interstitium

Question 25

Absorption is?

Answer 25

net mvmt INTO capillary from interstitium

Question 26

Kf (hydraulic conductance) is?

Answer 26

wall water permeability

↑ in glomerular caps
↓ in cerebral caps
↑ in injury

Question 27

Edema results from?

Answer 27

↑ ISF vol

ISF vol from filtration > ability of lymph to return it to circulation

Question 28

Causes of ↑ capillary hydrostatic P

Answer 28

heart failure

venous obstruction

Question 29

Cause of ↓ capillary oncotic P

Answer 29

hypoproteinemia

Question 30

Cause of ↑ hydraulic conductance

Answer 30

burn/trauma destruction of capillary wall

Question 31

Causes of ↓ lymph drainage

Answer 31

removed/irradiated lymph nodes
filariasis (parasite of lymph nodes)
lack of muscular activity

Question 32

What is Bulk Flow?

Answer 32

Movement of water and solutes together in and out of cell

Question 33

Lymph flow driven by?

Answer 33

contraction of smooth mm in lymph vessel and skeletal mm causes flow

Question 34

Oncotic pressure is what?

Answer 34

Osmotic P of proteins in vessel’s plasma,

U pulls water into circulatory system

Question 35

Oncotic pressure is opposing for to what?

Answer 35

hydrostatic P