3-Capillary Circulation Flashcards
function of capillaries
nutrient, gas, water, hormone, electrolyte, waste exchange
NOT proteins thru ever
permeability in diff tissues
-brain low perm aka blood brain barrier so tight spaces b/t endo cells
-kidney has leaky capillaries to allow filtration of blood
capillary flow dependent on
blood coming from upstream arterioles
+ regulation of precapillary resistance
myogenic regulation general
inc pressure = dec vessel lumen via stretch operated ion channels after initial stretch on vessel
myogenic response steps
- change in wall tension = stretch cell membrane
- membrane depolarization
- inc intracellular Ca
- enhance myosin-actin interactions
- contraction and dec lumen
metabolic regulation on vessels
by products of metabolism = vasodilators
i.e. adenosine, hydrogen ion, potassium ion, krebs cycle intermeds, hypercapnia
vascular SM relaxation
NO generated in endo cell then diffuses to smooth muscle to inhibit contraction and elicity vasodilation
if endothelial dysfunction from systemic disease then too much constriction not enough dilation
starling forces describe
how fluid moves in/out of capillaries and tissues
filtration favored when
fluid moves out of cap
inc hydrostatic pressure/ fluid pressure
dec oncotic pressure
reabsorption favored when
fluid moving into cap
inc osmotic pressure
dec hydrostatic pressure
hydrostatic pressure
aka fluid pressure so more fluid more pressure
i.e. vasodilation
osmotic/oncotic pressure
aka concentration pressure from solutes in fluid (proteins)
greater concentration of solutes = greater osmotic pressure
dehydration bc higher con of proteins in smaller volume
why lymph system drains fluid
bc not much fluid in interstitium so pressure neg
= filtration
