Question

Using the above diagram as a reference, define filtration and reabsorption. Include all the components influencing the flow and the pressures, and how they determine the actions at each end of the capillary.

Arterial end net filtration pressure - +10 mm Hg Mid capillary net filtration pressure =0mm Hg Venous end net filtration pressure =-7 mm Hg

Answer 1

Capillaries are the blood vessels of 5-10 micro meter in diameter.Capillaries supply oxygen,food and nutrition to the various part of the body.They are so tiny that during blood flow only a single blood cell can pass through at a time.Oxygen is exchanges and carbon dioxide is released into the blood.Molecules like lipid,gases and ions are diffused through the capillary wall from endothelial cell.Capillaries are composed of many tight junctions through which molecules can be excahnged.

Larger molecules pass through the pores of fenestrated capillaries and larger molecules passes through sinusoid gaps.Water passes in aout of the capillaries by osmosis.

Filtration-Flowof fluid in high volume moves from area of higher pressure to the area of lower pressure in the Tissues.

Reabsorbtion-The flow of fluid from are aof higher pressure to the area of lower pressure in capillaries.Two types of pressure take part in the movement of fluid,hydrostatic pressure and osmotic pressure.The pressure exerted by the blood against the wall of the capillaries is called as capillary hydrostatic pressure.The pressure that results in the reabsorbtion of the molecules back into the capillary is called osmotic pressure.When blood leaves artery and enter into the capillary the capillary hydrostatic pressure is observed to be 35mmHg and gradually the pressure decreases to 18mmHg as blood enters into the capillary and reaches the venous end.The pressure derivinf the fluid come out of the capillary is called net filtration pressure which is the interaction of hydrostatic and osmotic pressure.

NFT=CHP-BOCP.

NFT is always negative in number.

The value of NFT always changes at various site in the capillary bed.Near to the artery the NFT values is 10mmHg.

NFT=35mmHg-25mmHg=10mmHg.

At the mid of the capillary the CHP=BOCP=25mmHg.(NFT=0)Volume reamain same.

At the end of the capillary the CHP come back too 18mmHg and BOCP to 25mmHg dure to loss of fluid volume due to reabsorption.(NFT=-7).