varicose and spider veins, blood distribution, capillary exchange Flashcards
These are formed when venous valves become
weak or damaged.
varicose veins
describe the appearance of varicose veins
Veins are dilated and twisted in appearance
dilated venules close to the skin,
especially in the lower limb and face.
Spider veins
Describe the appearance of spider veins
They appear red, blue or purple, resembling a spider
web
At rest, the largest portion
of the blood is in
(these are considered to be the blood reservoirs)
in systemic
veins and venules, which
are considered “blood
reservoirs
Substances cross capillary walls by
- Diffusion
- Transcytosis
- Bulk flow
Substances such as oxygen, carbon dioxide, glucose,
amino acids, and some hormones cross capillary walls via
simple diffusion
Large, lipid-insoluble molecules (like insulin) cross
capillary walls in
in vesicles via transcytosis
Bulk flow is a
passive process in which large numbers
of ions, molecules, or particles in a fluid move
together in the same direction
Bulk flow occurs from an area of
higher pressure to an
area of lower pressure, and it continues as long as a
pressure difference exists
Pressure-driven movement of fluid and
solutes from blood capillaries into the interstitial fluid
Filtration
What promotes filtration?
- Blood hydrostatic pressure (BHP)
- interstitial fluid osmotic pressure (IFOP)
Reabsorption is
pressure-driven movement of fluid
and solutes from interstitial fluid into blood capillaries
What promotes reabsorption?
-Interstitial fluid hydrostatic pressure (IFHP)
-blood colloid osmotic pressure (BCOP)
Starling’s Law of the Capillaries: Under normal conditions, the volume of fluid and solutes
reabsorbed is almost as large as ________
Give the equation:
the volume filtered
Equation- NFP = (BHP + IFOP) − (BCOP + IFHP
