Reabsorption, the influx of tissue fluid into the capillaries, is driven by the BCOP.
Filtration predominates in the arterial end of the capillary
; in the middle section, the opposing pressures are virtually identical so there is no net exchange, whereas reabsorption predominates at the venule end of the capillary.
What affects capillary filtration?
The rate of exchange, in either direction, is determined by physical factors:
hydrostatic pressure, oncotic pressure
, and the physical nature of the barrier separating the blood and the interstitium of the tissue (i.e., the permeability of the vessel wall).
What are the forces that affect filtration and reabsorption in the capillaries?
Hydrostatic pressure
is a force generated by the pressure of fluid on the capillary walls either by the blood plasma or interstitial fluid. The net filtration pressure is the balance of the four Starling forces and determines the net flow of fluid across the capillary membrane.
What would increase capillary filtration?
Mechanisms of enhanced transcapillary filtration in response to elevations in arterial or venous pressure.
Elevations in arterial (P
a
) or venous (P
v
) pressure
increase capillary pressure, which favors enhanced capillary filtration (J
v
).
What decreases capillary filtration?
A
reduction in the interstitial oncotic pressure
increases the net oncotic pressure across the capillary endothelium (π
C
– π
i
), which opposes filtration and promotes reabsorption thereby serving as a mechanism to limit capillary filtration.
Which two pressures in the capillary determine filtration and or reabsorption?
In contrast, the movement of fluid from an area of higher pressure in the tissues into an area of lower pressure in the capillaries is reabsorption. Two types of pressure interact to drive each of these movements:
hydrostatic pressure and osmotic pressure
.
What factors affect blood flow and pressure?
Four major factors interact to affect blood pressure:
cardiac output, blood volume, peripheral resistance, and viscosity
. When these factors increase, blood pressure also increases. Arterial blood pressure is maintained within normal ranges by changes in cardiac output and peripheral resistance.
Which type of capillary is most common?
Capillary endothelial cells vary in structure depending upon the tissue type in which they are found.
Continuous capillaries
are the most common (i.e.muscle, fat, nervous tissue) have no transcellular perforations and the cells are joined by tight nonpermeable junctions.
What is capillary function?
Capillaries, the smallest and most numerous of the blood vessels, form the connection between the vessels that carry blood away from the heart (arteries) and the vessels that return blood to the heart (veins). The primary function of capillaries is
the exchange of materials between the blood and tissue cells
.
What is the purpose of capillary fluid exchange?
Capillary to Tissue Fluid Exchange
Capillaries are where fluids, gasses, nutrients, and wastes are
exchanged between the blood and body tissues by diffusion
. Capillary walls contain small pores that allow certain substances to pass into and out of the blood vessel.
Why does Net filtration occur?
Net filtration occurs
near the arterial end of the capillary since capillary hydrostatic pressure (CHP) is greater than blood colloidal osmotic pressure (BCOP)
. There is no net movement of fluid near the midpoint since CHP = BCOP. Net reabsorption occurs near the venous end since BCOP is greater than CHP.
Is a capillary?
| Capillary | TH H3.09.02.0.02001 | FMA 63194 | Anatomical terminology |
|---|
What happens with increased capillary permeability?
If capillary permeability is increased, as in
inflammation, proteins and large molecules are lost into the interstitial fluid
. This decreases the oncotic pressure gradient and so the hydrostatic pressure in the capillaries forces out more water, increasing the production of the tissue fluid.
What forces work to keep blood in the capillary?
As blood passes from arteries to veins through the capillary bed, fluids are exchanged by diffusion, the movement of molecules from areas of high pressure to low pressure. This relies on two forces:
hydrostatic pressure, or blood pressure, and osmotic pressure
, the constant pressure needed to keep blood from diffusing.
What is capillary filtration coefficient?
The capillary filtration coefficient (CFC) is assumed to
reflect both microvascular hydraulic conductivity and the number of perfused capillaries at a given moment
(precapillary sphincter activity). … CFC was calculated from the filtration rate induced by a fixed decrease in tissue pressure.
