Microcirculation Flashcards
the microcirculation is important b/c it is the site of
waste product removal, transport of nutrients to tissues
arteries branch into more arteries which branch into
nutrient arteries
nutrient arteries branch into
arterioles
arterioles branch to
terminal arteriole
off of terminal arteriole are
capillaries
b/w arterioles and capillaries are
precapillary sphincters
precarpillary sphincters regulate what
where blood goes in microcirculation
as you go to smaller arteries what happens to blood flow
it is slow
do capillaries have smooth muscle cells
no
capillary structure
single layer epithelial cells w/ basement membrane, small diameter
b/w endothelial cells in capillaries are
intercellular clefts
what are intercellular clefts
basically pores - space b/w cells
how do solutes and water move across capillary wall
intercellular cleft or plasmalemma vesicles
what kind of “pore” in brain
blood brain barrier
blood brain barrier, the endothelial cells have
tight junctions
tight junctions in brain allows
water to move but pretty much nothing else
liver pores, describe
very wide b/w endothelial cells
why are the pores in liver so wide (b/w endothelial cells)
liver job is to detoxify stuff, so you want everything to be able to get into liver
describe capillary endothelial in GI
pretty big pores, not as big as liver, not as small as muscle
kidney arrangement of pores for capillaries
fenestrated pores that penetrate to middle of endothelial cells
only system in body to have two capillary systems
kidney
kidney microcirulation allows filtering of: what and no filtering of
filtering of water, small molecules like glucose, but not proteins
you shouldn’t have what in your urine
proteins
all capillaries in body are not always
open
capillaries open and close depending on
tissue needs
vasomotion:
intermittent bloodflow through individual capillaries
when do capillaries open
when a lot of oxygen is being used up, the capillaries sense it and the sphincters open
b/c some capillaries are open and some closed, when we talk about capillary flow we talk about
the average of it all - so average blood flow, average pressure, etc
how do substances move from capillaries into interstitial (or vice versa)
diffusion
what is diffusion
random movement
what is net diffusion
goes from high concentration to low concentration
how do lipid soluble substances diffuse through capillaries
they just go right through the cell membrane
how do water soluble substances cross the capillaries
they have to go through the pores in the capillaries
the lower the permeability, how do they cross membrane
the harder it is for them to cross the membrane
how easily can water cross capillary and why
easily, it has a higher permeability
how easily can albumin cross capillary and why
difficult time, it is bigger than pore, they have low permeability
for water soluble the net rate of diffultion is proportional to what three things
concentration difference b/w the two sides of the membrane
size of the molecule
size of the pore
space b/w cells is called
interstitium
what fills the interstitium
interstiial fluid
what solid structures is in interstitium
collagen and proteoglycan
what is in proteoglycan
hyaluronic acid
proteins
interstitial fluid has same constituents as plasma except for:
lower concentrations of proteins
if you change ionic concentration of extracellular fluid (like making plasma hyperkalemic, high potassium) what will happen to potassium concentrations in interstitial fluid
it will also increase
what makes the extracellular fluid gell-like
the fluid is trapped in space among proteoglycan filaments
edema formation, you will increase what
free fluid in interstitial fluid
why does area swell, like with bee sting
fluida re moving into insterstitial fluid causing pockets of free fluid
in add’n to diffusion, what else is there in regards to movement across capillaries
filtration
what do you need to filter something
pressure
what four forces determine which way fluid moves
hydrostatic forces: capillary pressure & interstitial fluid
osmotic forces: plasma colloid osmotic pressure & interstitial fluid colloid osmotic pressure
what are the hydrostatic forces
capillary pressure
interstitial fluid pressure
capillary pressure is what
pressure of blodo in capillary
capillary pressure tends to move fluid which direction
out of capillary through the pores
interstitial fluid pressure if positive
pushes fluids into capillary
interstitial fluid pressure if negative
pulls fluids out of capillary
what are the two osmotic pressures
plasma colloid osmotic pressure
interstitial fluid colloid osmotic pressure
plasma colloid osmotic pressure:
pressure inside the capillary opposing filtration
colloid means
substance is bigger than what will just go through membrane
interstitial fluid colloid osmotic pressure:
trying to pull fluids out of the capillary
net filtration pressure depends on
average of all four of the forces acting on the capillary
what is the net filtration pressure equation
NFP) = Pc +/- Pif - pi p + pi if
what does NFP stand for
net filtration pressure
what does Pc stand for
capillary pressure
what does Pif stand for
interstitial fluid pressure
whatdoes pi p stand for
plasma colloid osmotic pressure
what does pi if stand for
interstitial fluid colloid osmotic pressure
all edema formation is
more fluids are filtered out than can be taken away, and they accumulate
what determines net filtration, how much totally filters out has to do with:
NFP and Kf
what is Kf
capillary filtration coefficient
what is capillary filtration coefficient, what does it tell you?
how many capillaries are open
number and size of pores in each capillary
if more capillaries are open, what happens to filtration
more filtration
liver vs kidney what will be easier to filter stuff out of
liver - big gaps are bigger
Kf is higher in kidney, skin, muscle, or liver
liver
where would you have the greatest net filtration: muscle, or in the liver?
liver
Net filtration = ? (equation)
NFP x Kf
capillary pressure is very
low
capillary presure at venous end is
10 mm Hg
capillary pressure at arterial end is
30 mm Hg
interstitial fluid pressure is always negativ with respsect to
tissue that surrounds it
interstitial fluid pressure is always
negative
osmosis is
net movement of water
higher concentration of solute dissolved in water, the more
osmotic pressure is going to exert
under normal conditions plasma protein concentration s about
7.3 g/dL
in capillary have the oncotic agents drawing water in b/c most proteins can’t
fit through the membrane/pores
plasma colloid osmotic pressure is about
28 mm Hg
to stop water moving into capillary you would have to
push out at 28 mm Hg
80% of collois osmotic pressure proteins is due to
albumin
average concentration of interstitial fluid colloid osmotic pressure is
3 g/dl
is average colloid osmotic pressure higher in liver or muscle
liver
arterial end of capillary, capillary pressure is about
30 mm Hg
what kind of interstitial pressure in arterial end of capillary
negative
total outward force in arterial end of capillary
41
forces moving fluid inward in arterial end of caiplary is
plasma colloid osmotic pressure
arterial end of capillary, ther eis net
filtration - fluids are filtered out
venous end of capillary, what is only thing that changes from arterial end
capillary pressure is much less, 10 instead of 30
what is capillary pressure at venous end of capillary
10
in venous end of capillary there is net
reabsorption
filtered vs reabsorption in capillary
morst filtered in arterial end most reabsorbed in venous end
excess fluid and proteins are picked up by
lymph vessels
not all fluid is reabsorbed by venous end, the excess is picked up by
lymph vessels
what could increase the netfiltration of fluids in tissue?
increase capillary pressure
anything that increases capillary pressure will increase
the forces moving fluids out
what would increase capillary pressure (generally)
more blood through a capillary
if right side of heart begins to fail what happens to venous pressure
increases (check)
if right atrial pressure is 20, is venous end capillary pressure 10?
no b/c then there would be no blood flow, all the capillary pressure has to increase
anything that affects venous pressure will also affect
capillary pressure
if pressures get higher what happens to filtration ratio in capillaries
increase
if pressures get higher what happens to filtration ratio in capillaries what does it do regarding fluid
extra - might get edema
left side heart failure and tries to exercise, and left heart can’t keep pumping out enough blood for body and eight heart pumps out a lot, how do they die?
fluid going out so much they have pulmonary edema
what else might increase filtration besides capillary pressure (body wise)
if the proteins decrease (albumin) then you wouldn’t be able to keep the fluids int he vessel
if you lose protein in urine and protein concentrations start to fall, say it goes from 28 to 15, what happens to fluid movement?
they will increase everywhere in body, they will move out of vessel and will get edema everywhere
bodywise if you take pressure from capillaryes everywhere in body what will you see
total outward force is about 28.3 and total inward is a little less, 28, so:
net outward force everywhere in body
net outward force everywhere in body means
there is net filtration everywhere in body
how much net filtration per minute
2 ml/min
how much per minute is filterting out of all blood vessels in body
2 ml /min
when blood circulates throughout your whole body there is excess filtration of about
2 ml /min
2 ml/min has to be picked up or else it will
accumulate
what picks up the excess filtration, drains the tissues?
lymphatic system
accessory route through which fluid, proteins and large particulate matter can flow from the interstitial spaces into the blood: what is this
lymphatic system
only what are reabsorbed back into vessles (liek venuous end)
only fluids, not proteins
if proteins are filtered out of capillaries they can’t be
reabsorbed
only way proteins can be reabsorbed back into system are through
lymphatics
lymph flows ____ from a tissue
away
lymph goes where
right lymphatic durct or thoracic duct
what is the largest lymph vessel in body
right lympahtic
lymph vessles drain into
right and left subclavian veins
if lymph vessel gets clogged you will see
edema formation in that leg b/c the edema is not drained
endothelial cells of lymph have
flaps on them
the flaps (endothelial valves) on the lymph can
open and allows large proteins to enter
permeability of lymph capillaries
very high
what tissues have greatest amount of lymph flow
liver and intestines
what tissue has most concentration of proteins in lymph
liver
as there is more water in interstitial fluid, what happens to lymph flow
increases
the more stuff is filtered out, the more lymph
flow increases
what happens at lymph plateau if we continue to increase filtration?
edema
when lymph becomes saturated,any further increase in filtration out of capillaries produce
edema
review pg 32
32
understand why elecated capillary presure would increase lymph flow, etc
hemorrhage how would that change lymph flow
capillary pressure decreased so lymph flow will change to net reabsorption to try to make up for lost fluid and try to increase blood volume so individual can live
severe dehydration does what to lymph flow
changes from net filtration to net reabsorption
vasodilator will do what to caipllary pressure
increase
histamine does what
increase permeability of capillary & is vasodilator
what does EPI do
open airways, consstrict vessels, increase pumping of heart
lymphatics have ___ and ____ Just like veins
pumps and valves
review pg 34
34
