Intermittent

Not constant flow.

• Act as a switch to open and close blood flow to the capillaries.
• Opens and closes depending of the tissue's need for O₂

• Used to describe the way that blood moves through capillaries.

• Not much gets through in the brain.
• Big pores in Liver and Kidney.

• Lipid soluble substance (O₂,CO₂) pass right through.(simple diffusion) Main form of transport.
• Small water soluble molecules (Na, K, glucose, AA)
• Proteins move by vesicular transport. Once they are in, they usually can't get out.

J= DA(D_c/D_x)

J:net rate of diffusion in moles or grams/time

D: Diffusion coeficient. Large molecules and high viscosity lowers coeficient.

A: Surface area of the membrane.

D_c: Concentration difference across the membrane

D_x: Thickness of membrane

Has to do with concentration of protein.

Determines if there will be net filtration (+ net pressure) or net absorption(- net pressure)

P_c:capillary hydrostatic pressure. Depends on artery and vein pressure.(+)

P_i:interstitial hydrostatic pressure. (-)

πc:capillary oncotic(colloid osmotic) pressure.

πi: interstitial oncotic(colloid osmotic) pressure.

K_f:hydraulic conductance (water permeability) ml/min.mmHg

Fluid movement= K_f x (sum of forces)

K_f

• Is the water permeability of the capillary wall.
• Determines magnitude of water movement at a given pressure difference.
• Depends on anatomical characteristics in capillary wall e.g. size of cleft, fenestration of the wall.
• Is lowest in cerebral(brain) and highest in glomerular(kidney) capillaries.
• Increases in capillaries injury e.g. toxins or burn.

• Increase: Arteriolar dialation, Venous constriction.
• Decrease:Arteriolar constriction(e.g hemorrhage)

Increase: loss of fluid but not protein. (e.g. dehydration or diarrhea)

Decrease: Less concentrated plasma protein. (e.g. liver and renal diseases, infusion of saline for bleeding compensation)

More negative thoracic pressure. Leads to more filtration.(e.g. respitory distress syndrome)

• Impaired lymphatic system. (e.g. tumor in lymph node)
•  Increased capillary permeability. (e.g. burns)

Lymphatic: 1-3L/day

Blood: 7200L/day

0.02% of blood goes through lymphatic system.

volume of interstitial fluid(due to filtration out of the capillaries)> ability of lymphatics to return to circulation.

GO LOOK At DiffErenT CAUSES!!!!

Filariasis

• Parasitic infection of lymph nodes
• Type of Edema