Arteries & Veins

cgeorge's version from 2016-02-24 14:37


Question Answer
Describe structure of capillaryThin wall of endothelial cells sittin on basal lamina. 5-10um diameter, wider at venous end. Dont have smooth muscle or elastin.
Rate of diffusion depends on 3 things (the equation)1)Permeability coefficient 2) Conc grad 3) Area
How can we change flow in capillaries?Changing pressure of the blood thats coming in from the arterioles. Cant change radius of a capillary
Dilating arterioles increases or decreases pressure in capillaries?Increases pressure (not alot of energy is lost)
Constricting arterioles increases or decreases pressure in the capillaries?Decreases pressure (alot of energy is lost)
3 mechanisms of exchange between capillary and cellDiffusion, vesicular transport and bulk transport
What pressure does blood enter the capillaries?35mmHg
5 starling forces1) Blood enters capillary with hydrostatic pressure of 35mmHg 2)Capillary oncotic pressure is 25mmHg 3) Hydrostatic pressure of interstitum is 0mmHg 4)Interstitial oncotic pressure is also 0 5)Blood leaves capillary with hydrostatic pressure of 15mmHg
Difference between hydrostatic pressure in glomerulus capillaries vs systemic capillaries?By the time blood leaves capillaries, hydrostatic P is quite low, in glomerulus in the efferent arteriole u still have alot of pressure
Define oncotic pressureOsmotic pressure due to plasma proteins
Difference between oncotic pressure in glomerulus capillaries and systemic capillaries?Oncotic pressure is pretty stable across systemic capillaries. In glomerulus, oncotic pressure increases across the system
Why does filtration cause fluid to leave the capillary at the arteriolar end of capillary?Hydrostatic pressure > Oncotic pressure
Why does filtration cause reabsorption of fluid into capillary at venouc end of capillaryHydrostatic pressure < Oncotic presure
How is lymph returned to the venous circulation?Via subclavian veins in the chest
Describe structure/characteristics of veinsLess smooth muscle in tunica medica than arteries. Quite floppy, have capacity to hold large volumes of blood. Valves prevent backflow
Increasing hydrostatic pressure by 1mmHg leads to an increase in arterial volume of1ml
Increasing hydrostatic pressure by 1mmHg leads to an increase in venous volume of6-10ml. This is cus veins are highly compliant