2.7

Question 1

Definition of Microcirculation

Answer 1

Functions of the capillaries and the lymphatic vessels

Question 2

Define Dichotomous Arborization

Answer 2

contineously dividing into two branches

Question 3

Job of capillaries?

Answer 3

site of exchange of nutrients, waste products, fluids

Question 4

structure of a capillarie?

Answer 4

thin wall

single layer endothelium

Question 5

what is the function of Mwtarterioles?

Answer 5

Shunting of blood from arteriole to venule without nutrient flow (when precapillarie sphincters are closed)

Question 6

what controlls precapillarie sphincters?

Answer 6

local regulation

vasodilator substances- Prostacyclin, NO

Question 7

capillary types? location?

Answer 7

1. continuous (brain)
2. fenestrated (absorptive tissues)
3. discontinuous (spleen, liver)

Question 8

what are the 2 pathways of diffusion from the capillary + examples?

Answer 8

1. Transcellular: Lipid soluble like O2,CO2

2. Paracellular: Water soluble like water, ions, glucose

Question 9

how does fluid pass btw plasma and interstitial fluids compartments?

Answer 9

through the capillary wall via osmosis

*we need aquueous pores and pressure difference

Question 10

what are Starling Forces?

Answer 10

Pressure difference, Hydrostatic and Osmotic pressure on both sides of the membrane

Question 11

define Starling’s Hypothesis

Answer 11

the fluid movement due to filtration across the wall of a capillary is dependent on the balance between the hydrostatic pressure gradient and the oncotic pressure gradient across the capillary

Question 12

the force of blood pressure on the wall tends to

Answer 12

force fluids out

Question 13

Starling’s equation

Answer 13

Jv = Kf [(Pc-Pi)-(Πc - Πi)]
Jv = Net fluid movement (ml/min). A positive value indicates movement out of the circulation.
Kf = Vascular Permeability Coefficient
Pc = Capillary hydrostatic pressure
Pi = Interstitial hydrostatic pressure
Πc = Capillary oncotic pressure
Πi = Interstitial oncotic pressure

Question 14

define what is filtration?

absorption?

Answer 14

Filtration= fluid movement out of capillary and into interstitium
Absorption= fluid movement into the capillary from the interstitium

Question 15

describe capillary hydrostatic pressure

Answer 15

• favors filtration

- starts at 30-40 mmHg and drops to 15 mmHg (over the length of the capillary)

Question 16

describe interstitial hydrostatic pressure

Answer 16

• opposes filtration

- near 0 to -5 mmHg

Question 17

describe capillary oncotic pressure

Answer 17

• opposes filtration
• 25 mmHg
• if there are more plasma proteins -> increased capillary oncotic pressure -> less fluids move into the interstitium

Question 18

describe interstitial oncotic pressure

Answer 18

• favors filtratior
• determined by the describe interstitial protein conc
• normally it is low

Question 19

what regulates precapillary spinchters?

Answer 19

they only have local regulation

regulated by the local chemicals