iphy 3430 10-25-11. exchange of materials in capillaries diffusion bulk flow
TRANSCRIPT
Diffusion:
When the blood reaches the capillaries, many nutrients, O2, and metabolic end products diffuse out/in (down concentration gradients) between the blood and cells.
Cellular utilization or production of materials causes diffusion gradient to exist between blood and cells.
Bulk Flow
Plasma (minus most plasma proteins) is moved by bulk flow out of the capillaries, moving all water soluble materials to the cells, and then most of the water is restored back to the circulation, carrying wastes.
Forces: Capillary blood pressure (outward) Plasma colloid osmotic pressure (inward)
beginning end
BP = 37 BP = 17COP = 25 COP = 25
37-25 = 12 out 25-17 = 8 in
Lymph circulation picks up the rest
unabsorbed “water” containing wastes, ions, etc from extracellular fluid spaceloose plasma proteinsloose red blood cellscell debrispathogenscancer cells
Lymph flow caused by:
1. Skeletal muscle contraction2. Smooth muscle contraction in
walls of lymph vessels3. SNS stimulation to walls of lymph
vessels
Excretory System
Roles:remove wastesbalance body water contentbalance body ionic contentbalance acid-base balance
Kidney also regulates RBC’s and secretes renin as part of regulation of blood pressure
Kidney: by regulating blood water, ionic and H+ content, can regulate extracellular fluid and cell water, ionic and H+ content
Extracellular fluid
blood
Water, ions and H+
If blood water drops, increase blood ion content, and withdrawwater from extracellular tissues, and then water would leave cell
Plus,…
1. adrenal gland (aldosterone)2. hypothalamus and posterior
lobe of the pituitary (vasopressin)
3. Heart atrium (atrial natriuretic factor)
How glomerular filtration can be varied:Increased blood pressure65- (30 + 15) = 20 mm Hg
blood
Bowman’s Capsule 15
BP = 65 COP = 30
How glomerular filtration can be varied:Dehydration55- (35 + 15) = 10 mm Hg
blood
Bowman’s Capsule 15
BP = 55 COP = 35