Author Question: Describe the normal pressures or flows at the arterial end of the capillary. a. Electrolytes move ... (Read 32 times)

evelyn o bentley · **on:** Jul 16, 2018

Describe the normal pressures or flows at the arterial end of the capillary.

a. Electrolytes move from the interstitium into the capillary.
b. Hydrostatic pressure is approximately 24 mm Hg.
c. Osmotic pressure is approximately 30 mm Hg.
d. Plasma minus the proteins flows into the interstitium.

Question 2

Which of the following factors contributes to reabsorption of tissue fluid in dependent regions of the body?

a. Hydrostatic pressure of 100 mm Hg
b. Low capillary permeability
c. Low interstitial osmotic pressure
d. Pumping action of skeletal muscles

CharlieArnold · **Reply #1 on:** Jul 16, 2018

Answer to Question 1

ANS: D
For example, in a typical capillary, blood pressure is approximately 30 mm Hg at the arterial end and approximately 20 mm Hg at the venous end (Figure 12-6). Colloid osmotic pressure of the intravascular fluid remains constant at approximately 25 mm Hg. Hydrostatic pressure along the capillary continually decreases. At the arterial end, hydrostatic pressure normally exceeds osmotic pressure and water flows out of the vascular space into the interstitial space.

Answer to Question 2

ANS: D
Because of hydrostatic effects, capillary pressure in the feet can be as high as 100 mm Hg when an individual is standing. Reabsorption of tissue fluid can be accomplished although hydrostatic pressure greatly exceeds colloidal osmotic pressure. Three factors favor reabsorption under these circumstances. First, high intravascular hydrostatic pressure is somewhat balanced by a propor-tionally greater interstitial pressure. Second, the pumping action of the skeletal muscles sur-rounding leg veins lowers venous pressures. Third, lymph flow back to the thorax is enhanced by a similar mechanism. This facilitates clearance of excess interstitial fluid.