Microcirculation

Question 1

what is microcirculation?

Answer 1

characteristics of capillaries & lymphatic vessels

Question 2

microcirculation lacks a ____

Answer 2

nerve supply (endothelial cells)

Question 3

what is the only type of control that microcirculation has?

Answer 3

local control

Question 4

where is microcirculation located?

Answer 4

connective tissue only

Question 5

what is microcirculation composed of?

Answer 5

only squamous epithelial tissue (endothelium) with thin basal lamina

Question 6

what are the 2 types of capillaries?

Answer 6

continuous
fenestrated

Question 7

where are continuous capillaries located?

Answer 7

blood brain barrier, muscle, nervous tissue
(tight junctions, H2O should not leak out)

Question 8

where are fenestrated capillaries located?

Answer 8

kidney & small intestine
(have holes, H2O can leak out)

Question 9

which type of capillary has a higher filtration rate?

Answer 9

fenestrated

Question 10

movement across the wall of the capillary & lymphatic vessels occurs by ____

Answer 10

diffusion

Question 11

what substances move directly through the phospholipid bilayer?

Answer 11

gases (O2, CO2) & lipid soluble substances

Question 12

what substances move through pores or at cell junctions?

Answer 12

ions & water

Question 13

what factors increase diffusion?

Answer 13

• increased concentration gradient
• increased temperature
• increased surface area
• increased # of pores/channels
• decreased distance

Question 14

lymph is a ___ pressure

Answer 14

negative (eg. -5mmHg)
“lymph sucks”

Question 15

how would a decrease in plasma colloid osmotic pressure impact lymph flow?

Answer 15

increase lymph flow

Question 16

capillaries in what organ have the lowest capillary permeability to plasma molecules?

Answer 16

brain
- continuous capillaries (tight junctions) only allow extremely small molecules such as water, O2, CO2 in/out of brain tissue

Question 17

why does albumin have a slow rate of net movement across the capillary wall?

Answer 17

albumin is not lipid soluble

Question 18

movement of solutes such as Na+ across the capillary walls occurs primarily by ____

Answer 18

diffusion

Question 19

movement of water occurs by ____

Answer 19

bulk flow

Question 20

what is bulk flow?

Answer 20

movement of water according to the balance between the pushing & pulling forces between the capillary & interstitial fluid

Question 21

name the pushing forces of bulk flow

Answer 21

capillary (Pc) & interstitial (Pif) hydrostatic pressures

Question 22

hydrostatic pressure is due to…

Answer 22

water pressure in the capillary or interstitial fluid

Question 23

what increases hydrostatic pressure?

Answer 23

more volume due to larger diameter vessel or vasodilation

Question 24

name the pulling forces

Answer 24

capillary (TTp) and interstitial (TTif) osmotic/oncotic pressures

Question 25

what type of osmotic pressure do capillaries have and why?

Answer 25

plasma colloidal osmotic pressure due to albumin

Question 26

the interstitial fluid osmotic/oncotic pressure is due to...

Answer 26

proteins in the IF such as collagen & elastin

Question 27

in the kidney, the glomerulus is the ____, and the IF is termed ____

Answer 27

capillary Bowman's space

Question 28

what type of capillary has a filtration coefficient?

Answer 28

very porous (eg. glomerulus)

Question 29

how is the net filtration rate of porous capillaries determined?

Answer 29

filtration coefficient x bulk flow (net filtration pressure)

Question 30

what does it mean when bulk flow is negative?

Answer 30

absorption: water moving IN to capillary

Question 31

what does it mean when bulk flow is positive?

Answer 31

filtration: water moving OUT of capillary

Question 32

what has the fastest net movement across capillary walls?

Answer 32

oxygen

Question 33

where is there no interstitial fluid oncotic pressure?

Answer 33

glomerulus

Question 34

when calculating bulk flow, what sign goes in front of capillary hydrostatic pressure?

Answer 34

+

Question 35

when calculating bulk flow, what sign goes in front of interstitial fluid hydrostatic pressure?

Answer 35

-

Question 36

when calculating bulk flow, what sign goes in front of interstitial fluid colloidal osmotic pressure?

Answer 36

+

Question 37

when calculating bulk flow, what sign goes in front of colloidal osmotic pressure of plasma?

Answer 37

-

Question 38

if interstitial fluid hydrostatic pressure increases, what happens to lymph flow?

Answer 38

increases

Question 39

how is bulk flow calculated?

Answer 39

Pc - Pif + TTif - TTc

Question 40

what would happen to capillary filtration rate if capillary water permeability decreased?

Answer 40

decreased filtration rate

Question 41

what changes in microcirculation would occur with a decrease in the diameter of a precapillary arteriole?

Answer 41

decreased - capillary filtration rate - pressure - volume - conductance increased: - resistance

Question 42

an increase in what factors would increase lymph flow?

Answer 42

increased capillary filtration rate & lymphatic pump activity - increased hydraulic conductivity of capillary wall - increased capillary hydrostatic pressure - increased interstitial hydrostatic pressure

Question 43

an increase in what pressures would decrease capillary filtration rate?

Answer 43

increased plasma colloid osmotic pressure Increased IF hydrostatic pressure

Question 44

a decrease in what factors would increase lymph flow?

Answer 44

plasma colloid osmotic pressure

Question 45

an increase in what factors would increase capillary filtration rate?

Answer 45

increased capillary wall hydraulic conductivity (permeability to water)