21.2 Capillary Exchange

Question 1

capillary exchange

Answer 1

-the movement of substances between blood and interstitial fluid

Question 2

diffusion

Answer 2

• the most important method of capillary exchange, caused by concentration gradients between blood and interstitial fluid
• O2, CO2, glucose, amino acids, and hormones enter and leave capillaries by this method

Question 3

transcytosis

Answer 3

• the method of capillary exchange that involves tiny pinocytic vesicles enclosing substances in blood plasma to allow for their transfer into cells
• this is required for large lipid-insoluble molecules such as insulin, and antibodies and other large proteins

Question 4

bulk flow

Answer 4

-the process by which a large number of ions, molecules, or particles in a fluid can move together from an area of higher fluid pressure to an area of lower fluid pressure

Question 5

filtration

Answer 5

• the bulk flow of fluid solutes from blood capillaries into interstitial fluids
• occurs when BHP+IFOP is larger than BCOP+IFHP

Question 6

reabsorption

Answer 6

• the bulk flow of fluid solutes from interstitial fluid into blood capillaries
• occurs when BCOP+IFHP is larger than BHP+IFOP

Question 7

net filtration pressure

Answer 7

• known by it’s acronym NFP
• formula is NFP=(BHP+IFOP)-(IFHP+BCOP)
• sign determines whether filtration (+’ve) or reabsorption (-‘ve) is occurring
• typically +10mmHg at arterial end of capillaries and -9mmHg at the venous end

Question 8

blood hydrostatic pressure

Answer 8

• the hydrostatic pressure exerted by the water in blood plasma against blood vessel walls
• contributes to filtration as a high value indicates fluid wants to push from the vessel wall into interstitial fluid
• typically 35 mmHg at the arterial end of a capillary and 16mmHg at the venous end

Question 9

interstitial fluid hydrostatic pressure

Answer 9

• the hydrostatic pressure exerted by interstitial fluid against blood vessel walls
• contributes to reabsorption as a high value indicates fluid wants to push from the interstitial fluid into the blood vessels
• typically small and assumed 0mmHg in this course

Question 10

blood colloid osmotic pressure

Answer 10

• the osmotic pressure caused by large plasma proteins in blood which cannot pass through fenestrations
• contributes to reabsorption as the osmotic pressure wants to dilute the blood, pulling water from the IF into the plasma
• typically 26mmHg

Question 11

interstitial fluid osmotic pressure

Answer 11

• the osmotic pressure caused by the small amount of proteins in interstitial fluid
• contributes to filtration as the fluid wants to dilute the IF, pulling water from the plasma and into the IF