lecture 7: chapter 16 Flashcards
what does the term microcirulation refer to
functions of the capillaries and the neighboring lymphatic vessels
what percetange of blood is present in the capilarries at ayn given time
5%
TRUE or false; sicne there is only 5% of blood in criualtion in capilaries it is not imporant
false, it is imporatntfor all gaseous exhanges
what is good about having 3-10 billion capitlies
there is a larger surface area which allows them to perform the function of solute and fluid exchange
=alot of plcaces to move places around
what are the 4 functions of the microcirculation
Ensures constant plasma and interstitial fluid communication
Accelerates distribution of nutrients, hormones, and dissolves gases through tissues
Transports insoluble lipids and tissue proteins that cannot cross capillary walls
Flushes bacterial toxins and chemicals to immune system tissues
what is the capillary bed/plexus
it connects 1 arteriole to 1 venule
are vascular anastomoeses more common in veins or arteries
veins
what do arterial anatomsoes provide
altherate pathways (collateral channels) for blood to reach a body region
explain how arterial anastomoses provide altherane channels
If one branch is blocked, the collateral channel can supply the area with adequate blood supply
what is an example of arteriovenous anastomoese
thouroughfare channels
where are vascular anastomese common
joints, in skin, abdominal organs, brain, heart
what is the trajectory of blood in microcirculation
arteriole
meta arteriole
capillaries
venules
what is the composition of arterioles
one mono layer or endothelial cells and 1 layer of smoothe muscle
what is the compostion of meta arteriole
one mono layer of endothelial cells with occasional smooth muscle
what is the composition of capillaries
1 layer of endothelial with no smooth muscle cells at all
what is the composition of venules
1 mono layer of endo thelial and some smooth muscle
where is the pre capillary sphincter
present at the junction where the capilarie arises from the meta arteriole
what to sphincters respond to
local metabolytes
nerological signals
what is the function of the sphincters
regulate flow direction into true capillaires or throu0gh channels
guard the entrance to each capillary
what allows blood flow to be changed by sphincters
vasomotion-contraction and relation cycle of capillaruy sphinctets
what causes blood flow in capillary beds to constantly change routes
spinhcters
wht is blood flow regulated by and what does that mean
regulated by vasomotor nevres and local chemical condition, so it can either bypass or blood the cpillaries
true or false: blood always floods and flows through the enter capillary bed
no , it can be rediceted dependant on tissue needs
what are the 3 types of capillaries
continous
fenestrated
sinosoidal
where are continous capilaries usually found
in skin and muscles
true or false: continous capillaries are not efficent at moving substances in and out beacuse the endothelial cells are so close together
true
what is characteristic of endothelial cells in contious capilaries
the endothelial cells are so close so they provide an uninterupted lining
what are adjeacent cells held together with
tight junctions
what allows the passage of fluids in continous capillaries
interceullular clefts
where is an example of continous capillaries of the brain and why its used there
in the brain
there are tight junctions completely around the endothelium
constitute tje blood-brain barrier to make a protective agaisnt toxins
where are fenestrated capillaries found
where thers is active capilaru absoptions or filtrate formation occurs
(ex: small intestine, endocrine glands, kidneys
explain the endothelium in fenestrate capilarries
riddled with pores (fenestrations)
which type of capillarires have the greatest permeabilty to solutes anf fluids
fenestrate capiaires
true or false: since fenestrated capillaries have pores they dont have intercellular clefts
false, they do have
what are sinusoid (discontinous) capilaries
highly modified, leaky, fenestrated capillaries with large lumens
where are sinusoid (discontinous) capilaries
found in the liver, bone marrow, lympohid tissue and some endocrine organs
which capillaries have the biggests pores
discontinpous
what is the function of discontious capilaries
allow large molecules (proteins and blood cells) to pass between the blood and surronding tissues
true or false: has blood passes from conitnous to discontious is becomes more slugglish/less laminar
true
what are capillarys composed of
unicellular layer of endothelial cells surrounded by basement membrane
how does solute and water move accross capillar wall
intercellular cleft (space between cells) or by plasmalemma vesicles.
what is the dimater of capillaries
4-9 microns
what is the main passage of substances through capilary to tissue
through clefts
what are the smallest blood vessels
capillaries (allow only 1 single RBC to pass at a time)
what is the width of capillary intercullular slit pores
6-7 nanometers
what does the The permeability of the capillary pores for different substances varies according to
their molecular diameters.
true or false and why: The capillaries in different tissues have no differeces in their permeabilities
The capillaries in different tissues have extreme differences in their permeabilities
because of fenestrations
give an example of how different tissues have different permabiality
liver takes large molecules so their capilaries will habe a higher fenestration
how does water, ions, small molecules (gluocse) get diffuse
diffuse between adjacent endothelial cells
or through fenestrated capillaries
how do some ions like NA+, K+ ca2+ and Cl- diffuse through
though channels in cell membranes
how do large, water solluble compounds pass through/diffuse
pass thru fenestrated capillaroes (and occsionally though endothelial cells)
how do lipids and lipid solluble materials (o2 and co2) diffuse through
through endothelial cell membranes
how to plasma proteins diffuse through
cross endothelial lining in sinusoids (really large pores)
the larger the side the harder/easier to permeate
harder to [ermeate
true or false: since hemoglogin and albumin have the same molecular weight, they have the same permeability
false, albumin has a harder time permeating
why is albumin harder to permeat than hemoglobin
gibbs donnan effect
albumin have a greater osmotic force
explain why albumin has a greater osmotic force
albumin has a negative charge (attracts sodium inions)
albumin binds a small number of chloride ions (attracts more sodium ions)
explain why albmin has a hard time permeating
because of its greater osmotic force is pulls liquid towards it
Most important means by which substances are transferred between plasma and interstitial fluid is by wht
diffusion
since salt has a high osmptic force what does that do for diffusion
it attracts fluid in the capillary (pulls water out)
what is the space between cells called
interstitium
what is the fluid in the interstitium called
intersticial fluid
what is the consistency of interstiaual fluid
gel
what are the two major types of solid structures in the interstitium called
collagen fibers and proteoglycan filaments (coiled molecules composed of hyaloronic acid)
true or false: there is very little free fluid under normal conditions in interstitium
true
the collagen bundle fibers in the interstitium provide what
structure
explain the capillaru exhange at the arterial end of the capillary
fluid moves OUT of the capillaru
into the itnersticial fluid
explain capillary exchange at the venous end of cpailliar
fluid moves INTO capilary
OUT OF THE INTERSTICUAL FLUID
what are the 2 hydrostatic forces
capillary hydrostatic pressre
interstitial fluid hydrostatic pressure
where is capillary hydrostatic pressure higher and why
higher at the arteriolar end than venule
*because of ressitance)
where does capillary hydroststic pressure force fluid
forces fluid outward through capillary membrane
pushese fluid from cap to interstitium
Normally interstitial fluid hydrostatic pressure is negative or postive
negative
what is the negative pressure in the interstitual fluid hydrostrate pressure caused by
pumping action of lymphatics
the fluid is being constantly drained and leaking out of intstitum which helps push more fluid in
where does interstial fluid hydrostatic pressure force fluid
usually pushes fluid from cap to interstitcium (excep for when pressure is postive)
when interstitial fluid pressure is postivie what happens
it opposes filtration
capillary hydrostatic pressure is good for absoptin or filtration
filtration
interstial fluid hydrostatic pressure is good for filtration or absoprtion
reabsoption (when pos)
what are the osmotic forces
plasma colloid osmotic pressure
interstitial fluid osmotic pressure
what is another name for plasma colloid osmotic pressure
plasma oncotic pressure
what is the major determinants of oncotic oressure
plasma prteins
what is the most abundant plasma protein and what dos it generate
albumin, tgenerates 70% of oncotic oressure
plasma colloid osmotic pressure/plasma oncotic pressure tends to cause what
INAWARD (INTO CAPILLARY) MOVEMENT OF FLUID
WHAT IS another name for interstitial fluid osmotic poressure
interstitial fluid oncotic pressure
what is interstitual fluid osmotic pressure caused by
small amount of plasma proteins that leak into the interstial space
interstiaial fluid osmotic pressure tends to cause inward or outward movement of fluid
outward movement
plasma colloid osmotic pressure opposes what and what does that cause
opposes filtration, causing osmosis of water inward through the membrane
interstittial fluid colloid pressure promotes what and why
promotes filtration by causing osmosis of fluid outward thourgh membrane
what is filtration
The sum of the hydrostatic and osmotic forces favors the net movement of water from the capillary to the interstitial space
what is reabsorption
The sum of the hydrostatic and osmotic forces favors the net movement of water from the interstitial space to the capillary
what is the filtration rate
the net filtration pressire (NFP) multiplied by coefficent filtration
what is the NNFP formatila
NFP= PC - Pic - Pip + Piif
what is the filtration ocefficent
Kf
product of surfeace area times the hydraulic conductiveity of memberan
know the determinatnts of net fluid movement across capillaries
diagram of capt=illary and 4 pressures
what is the starling equilibrium
The Starling equation describes the net flow of fluid across a semipermeable membrane. It describes the balance between capillary pressure, interstitial pressure, and osmotic pressure.
what is the normal capillary hydrostatic oressure
approx 17 mmHg
what is the normal interstitial fluid pressure in most tissues
-3
what type of organs have positive interstitial pressueres
encapsultated organs
what is the negative interstitial fluid pressire caused by
pumping of lymphatic system
what os colloid osmotic pressure caused by
large proteins
what incrases the colloid osmotic effect of proteins
presence of negative ions on proteins (gibbs donnan)
whatis the reflection coeffiecent of capillaries
it quantitates the amount of protein that is reflected away from capillary nmemberna
what does a reflection coeeficent of 1 mean
all proteins are reflectted and none pass throg=ugh pores
what does a reflection coeefficent of 0 mean
it is permable to all proteins
true or false: physiologically you can neevr have a coeefiction of 1 or 0
true
go over the 3 slides about forces causing filtration, reabsorption ect
f
what is the net filtration pressure and what does that cause
0.3 mmHG which causes a net filtration rate pf 2 ml/min for entire body
(this means we are constantly moving more fluid from capilliary to interstirum than oppsoite)
even tthough the is a net outward force (moving fluid from cap to interticiun) do the vessels swell
no because of the draining from lympatic systems
where is the transition point
it is a point between filtration and reabsoption where there is equilifrium
is the transition point closer to venous end or arterial end
closer to venous
true or false: capillaries filter more than they reabsord
true
is the transition point always the same? give example
no it changes depending on the needs of the tissue (whether they need more filtration or reabsoprtion)
ex: in skeletal we need a lot of filtration so it wil, be cloed to venous side
during filtration, are we only moving fluid
no also moving oxygen, gluocse ect
during reabsorption are we only moving fluind?
no also waste products
