microcirculation, exchange of substances, venus circulation

Question 1

what is Microcirculation

Answer 1

The microcirculation is the circulation of the blood in the smallest blood vessels, the microvessels of the microvasculature present within organ tissues.

Question 2

exchange of materials is possible between blood and ECF is made by…

Answer 2

by permeable capillaries

Question 3

what is Diffusion

Answer 3

Diffusion is defined as the movement of individual molecules of a substance through a semipermeable barrier from an area of higher concentration to an area of lower concentration

Question 4

what affect the rate of diffusion?

Answer 4

The rate of diffusion depends on the concentration
gradient, permeability, and the surface area.

Question 5

what are the Two types of transport by diffusion:

Answer 5

Flow limited:
Diffusion limited:

Question 6

what is flow limited in diffusion:

Answer 6

Flow limited: For small molecules ot is only the rate of blood flow that limits the transport.

Question 7

what is diffusion limited in diffusion:

Answer 7

Diffusion limited: For large molecules (e.g. polypeptides) it is the rate of diffusion that limits the transport.

Question 8

explain diffusion of gases

Answer 8

Partial pressure of the gas drops in both directions:
towards the end of the capillary, and towards distant cells. The higher the actual oxygen consumption of the tissue, the higher will be the gradient for oxygen.

Question 9

local autoregulation in diffusion of gases

Answer 9

Cells getting less oxygen release more regulatory signals, and these open more capillaries in the vicinity of these cells.

Question 10

determine the pressure gradient for the fluids

Answer 10

Hydrostatic pressure and oncotic pressure of the blood
and of the tissue

Question 11

Phcap

Answer 11

hydrostatic pressure in the capillary

Question 12

Point

Answer 12

oncotic pressure in the interstitium

Question 13

Pocap

Answer 13

oncotic pressure in the capillary

Question 14

Phint

Answer 14

hydrostatic pressure in interstitium

Question 15

Effective pressures are the differences of the blood and tissue pressures eq

Answer 15

Pheffective = Phcap - Phint Poeffective = Pocap - Point

Question 16

The final effective filtration is the difference of he effective hydrostativ and effective oncotic pressures EQ

Answer 16

Peffective = Pheffective - Poeffective

Question 17

what does effective filtration show

Answer 17

The effective filtration pressure shows towards the tissue at the arterial side of the capillary

Question 18

The flow of fluid depends on

Answer 18

the effective pressure
and on the permeability

Question 19

Formation of ISF:

Answer 19

Water, electrolytes and anelectrolites with small molecular weight can permeate the capillary wall without restriction.

Question 20

Pathes of transport:

Answer 20

o Through fenestration
o Through interendothelial ways o In a transcellular way
o By cytosis (endo-, exo-, pyno)

Question 21

Forces determining transport:

Answer 21

Diffusion
Osmotic forces:
Electric forces:
1) Electroneutrality
2) Thermodynamic rule:
Hydrostatic pressure:

Question 22

Forces determining transport:Diffusion:

Answer 22

It is the most important factor to insure transport of substances. The greatest part of
substances crossing the capillary membrane is transported in this way.

Question 23

Forces determining transport:Osmotic forces

Answer 23

: The osmotic effect of the
proteins in the solution makes water to move. The water content inside will increase. This so- called oncotic pressure continuously gets the water to move into the intravasal compartments from the ISF.

Question 24

Forces determining transport:Electric forces

Answer 24

: If the movement of some components is restricted between two compartments, the concentration of the diffusible ions will be different in the two compartments after the balance develops:

Question 25

Forces determining transport: Electric forces: Electroneutrality and Thermodynamic rule

Answer 25

▪ Electroneutrality: The total amount of anions and cations have to be equal in certain compartments
▪ Thermodynamic rule: The product of the concentrations of diffusible ions must be equal on both sides of the membrane.

Question 26

Forces determining transport: Hydrostatic pressure:

Answer 26

The hydrostatic pressure coming from blood is not the same at the arterial
and the venous “end” of the capillary, that is why the net fluid flow is different.

Question 27

The venus circulation: function determined by:

Answer 27

Function is determined by: structure of the wall and venous valves.

Question 28

The venus circulation: characteristics

Answer 28

Characteristics of Venous System: capacitance-system (reservoir), 55 – 75 % of circulating blood reside in the veins.

Question 29

Factors Maintaining Venous Circulation

Answer 29

the work of the heart
Gravitation
Venous valves
Skeletal muscle pump
Changing pressure in chest and in abdomen