Capillary oncotic osmotic pressure: 25 mm Hg favours reabsorption
Interstital fluid oncotic osmotic pressure: 0-1 mm Hg favours filtration
25-0 = 25 mm Hg which favours reabsorption
Net Filtration pressure?
Arteriole end: (38+0) - (25+1) = 12 mm Hg filtration
Venous end: (16+0) - (25+1) = -10 mm Hg absorption
What is the effects of Net filtration pressure?
Net acrosss capilary Filtration > Absorption
3 L per day of filtation
lyphatic system will pick up all that is left and return to circulation
Factors effecting filtration/absorption
standing on feet increases hydrostatic pressure
injuries - capillaries damaged and leak fluid and proteins
histamine increases and capillary permeability to proteins
smaller than arterioles
connect capillaries to veins
little smooth mushc in walls
some exchange of material between blood and IF
valves allow unidirection of blood flow
Where are valves found in viens
in perpherial veins absent from central veins
How are veins a volume resovoir?
Expand with little change in pressure
60% of total blood in systemic is present in them at rest
veins hold a large volume with small pressure change due to high compliance
Skeletal muscle pump. What happens when it conracts and relaxes?
Contract: squeezes on veins increasing pressure, blood moves to the heart cannot move back because of the veins
relaxes: blood flows into the veins between muscles
Respiratory pump? Inspiration?
Inspiration causes a decrease in pressure in thoracic cavity which causes an increase in the pressure in the adominal cavity
pressure in the veins in the abdominal cavity creates gradient that favors blood movement to thoaric cavity
What happens with increased and decresed blood volume respect to venous pressure?
increased leads to increased venous pressure
decreased blood volume leads to decreased venous pressure
Venomotor tone? what causes an increase?
Venomotor tone = smooth muscle tension in veins
increase in venomotor tone is caused by contraction of smooth muscle in wall of vein. Leads to increase venous pressure and decreased venous compliance. Leads to increased stroke volume and increased cardiac output
system of vessles, nodes and organs
vessels that circulate excess filtrate
lymphatic veins drain into thoracic duct which empties into right atrium
filter lymph flowing thru the node. They are able to filter bacteria, toxins, or other foreign material