Exam 2 - part 6, transcapillary exchange (diffusion), venous return

what are the 3 routes which chemicals can pass through the capillary wall

diffusion, filtration, pinocytosis

do glucose and oxygen tend to diffuse into or out of the blood

out of

does carbon dioxide and other waste usually diffuse into or out of the blood

into

capillary diffusion can only occur if

1. solute can permeate through plasma membrane of endothelial cell

2. finds passage large enough

what kind of molecules diffuse easily though the plasma membranes

lipid soluble

steroid hormones, o2, co2

what kinds of molecules must pass through filtration and intercellular clefts

water-soluble

glucose, electrolytes

which end of the capillary bed does fluid filter out of? which end does it osmotically re-enter?

arterial, venous

what drives fluid out of the capillary

blood hydrostatic pressure

(high on arterial end, low on venous)

what draws fluid into the capillary

colloid osmotic pressure

oncotic pressure is the net colloid osmotic pressure and is found by subtracting ___ from ____

blood COP - tissue COP

what % of fluid that is filtered by the capillaries is reabsorbed

85

which capillaries do not reabsorb any of the fluid they filter

kidney capillaries in glomeruli

which capillaries completely absorb the fluids they filter in order to keep fluid out of air spaces

alveolar capillaries in lungs

accumulation of excess fluid in a tissue is known as

edema

what are the primary causes of edema

1. increased capillary filtration

2. reduced capillary reabsorption due to decreased protein

3. obstructed lymphatic drainage

what forms the pinocytic vesicles that are used by some substances in order to transfer across the capillary wall

pinching off of endothelial cell membrane

what is pinocytosis responsible for moving

large lipid-soluble molecules

what does venous return rely on

pressure gradient, gravity, skeletal muscle pump, thoracic pump, cardiac suction

when you inhale, the thoracic cavity expands causing thoracic pressure to ____ and abdominal pressure to ___

decrease, increase

does blood flow faster with inhalation or exhalation

inhalation

exercise causes an increase in ___ and ___

co, bp