microcirculation Flashcards
what is the arteriole at the end of arteriovenous anastomoses called
terminal arteriole
after terminal arteriole what is the arteriole that follows
metarteriole
what come off of metaarterioles
true capillaries
how many true capillary per capillary bed
10-100 true capillaries per capillary bed
what is the structure after true capillaries after gaseous exchange
thorough fare channel
what is the distance between meta arteriole and thorough fare channel
vascular shunt
what drains thorough fare channel
post capillary venule
what is the smooth muscle rings that covers the true capillaries
sphincter- controls blood flow to true capillaries to take it to the tissue cells
what do the sphincters on the true capillaries do
control blood flow to true capillaries to take it to the tissue cells
what are the sphincters on the true capillaries called
pre capillary sphincter
what is the pre capillary sphincter
a ring of smooth muscle tissue if it constricts, no blood can come out to the capillaries, if it dilates blood can be delivered to the true capillaries
what are the pre capillary sphincters controlled by
sympathetic nervous system
how many litres is the intracellular fluid
28 litres
how many litres in the intersitial fluid
10.4 litres
how many litres in the transcellular fluid
0.8 ml
how many litres are in the plasma fluid
2.8 litres
what two components is blood made from
cells and plasma
what does hpc mean
hydrostatic pressure within the capillaries. pressure designed to push fluid out of capillary bed
what is the usual hydrostatic pressure in the capillary at the arteriole end of the vascular shunt
35 mmhg
if the systolic pressure drops what happens to the hpc
also decreases
what is osmotic pressure
the pressure exerted by albumin and plasma proteins to pull water into the bloodstream
what is the standard osmotic capillary pressure
25-26mmhg
what is the standard hp if hydrostatic pressure of interstitial fluid
0mmhg
what does the hydrostatic pressure of the interstitial fluid do
pushes the if into capillary bed but ususlly 0 so no change
what is standard osmotic pressure of interstitial fluid
1mmhg as usually has some solutes
what does osmotic pressure of the interstitial fluid do
pull fluid from capillary bed into interstitial space
what does the hydrostatic pressure of the capillary drop to at the venous end
17mmhg
what happens to the osmotic pressure of the capillary at the venous end
it is retained remains 25-26mmhg unless albumin is lost
what happens to the hydrostatic pressure of the interstitial fluid at the venule end
remains 0mmhg
how is net filtration pressure of arteriole end calculated
(35mmhg+1mmhg)-(25+0)=11mhg
out - in
(hydrostatic pressure of capillary+osmotic pressure of interstitial fluid) -(osmotic pressure of capillary+hydrostatic pressure of interstitial fluid)
net flow out
how is net filtration pressure of the venule end carried out
(17mmhg+ 1) - (25+0)
hydrostatic pressure at the venule end of the capillary+ osmotic pressure of intersitial fluid) - (osmotic pressure at venule endof capillary+ hydrostatic pressure of interstitial fluid)
-7 mmhg
net flow in
what can lead to severe oedema
hypoalbuminaemia can lead to severe oedema
hypoproteinaemia
diseases such as glomerulonephritis can cause albumin proteins to be lost this decreases oncotic pressure what will this do to the fluid going in and out along the vascular shunt
more fluid pushed out and less fluid pushed in causing oedema
if someone develops cancer (hodgkins lymphoma or non hodgkins ) and an occlusion is produced within lymphatic vessel this impairs the ability of the lymphatic vessel to drain causing backflow what can this lead to
area swells and oedema is caused
backflow of lymph causes hydrostatic pressure of interstitial fluid to rise above 0 causing more fluid to be pushed out. leads to stagnation
what is an anastomoses
alternative or collateral channels for blood to flow through
what are the three types of anastomoses
arterial anastomoses
venous anastomoses
arteriovenous anastomoses
what anastamoses are the most common
venous anastomoses
arteriovenous anastamoses from where to where in the vascular shunt
metaarteriole to thorough fare channel
arterial anastomoses what is the most important one
circle of willis
circle of willis
if there is a clot in the posteriorcommunicating arteries , there is an alternative route for blood flow in the circle of willis between anterior communicating arteries and posterior communicating arteries
when someone is exercising they might be producing co2 and lactic acid high co2 in the bloodstream causes high hydrogen ions and high amounts of lactic acid what does this do to blood vessels
localised/active active hyperaemia
if mean arterial pressure is high what does this lead to
vasoconstriction to prevent smaller cerebral vessels from rupturing,
what happens when there is a decrease in map
vasodilation to increase blood flow
if mean arterial pressure is not high enough what can it cause symptoms wise
syncopy and fainting
if for example there is an obstruction in the lung the area cannot be oxygenated what will happen to ensure sufficient oxygenation of blood
vessel vasoconstricts to divert blood to area with more oxygen
during fight or flight what happens to vessels around the gi tract and skin and kidney s
vasoconstriction to divert blood away from git and skin and divert it to heart skeletal muscle, lungs and brain
arteriovenous malformation what is it
people do not have true capillaries, capillaries dampen pressure but in a av malformation high pressure from artery goes straight to vein leading them to become coiled up and can cause ruptures. common in brain but rare condition
how is av malformation treated
embolous is created to divert blood flow to prevent rupturing
what is ascites
water belly
what is elephentatis or bancroftians filariasis
caused by nematode infection. blocked lymph nodes
