FINAL EXAM - Lecture 2 Flashcards
Fluid moving out of the capillary is called
filtration
Fluid moving into the capillary is called
re-absorption
As blood moves further through vascular resistance, the pressure is
reduced
When youre taking a blood pressure, youre looking at pressure in
large arteries
When are you measuring a low pressure area as a bedside nurse
CVP
As blood is getting further from the heart, it is going through _________ cross-sectional areas.
More and more
The main drop in blood pressure between large arteries and capillaries is due to
high vascular resistance, not because of the multiple pathways it takes.
Resistance blood vessels in the systemic circulation is
arterioles
If you have a pressor that can constrict ______, that drives up blood pressure.
Arterioles
The blood vessels that contract and relax, doesnt usually happen in ______, but more in the ___ and _____.
Large arteries; small; arterioles
Flow equals
delta pressure divided by resistance
How many capillaries do we have in the body?
10+ BILLION
Capillaries are the primary place for
nutrient, waste product exchange to occur
Blood flow through the capillaries is controlled by
arterioles
What kind of muscle are arterioles?
Smooth muscle
Dilation of the arterioles will result in
increased blood flow for downstream tissues
How much surface area do we have of capillaries?
500-700 square meters
Small arteries have how many layers of smooth muscle cells?
4 layers
What controls the blood flow of capillaries? (not the physical reason of contracting)
metabolic rate
Total cross-sectional surface area of aorta is
4.5cm2
Velocity of aorta is _____. why?
High. Low surface area with a ton of cardiac output
Vena cavae surface area
18cm2
2 vena cavae’s that are 3cm each.
internal diameter of arterioles is
30um (micrometers)
Discuss the internal diameter vs wall thickness of arterioles
30um internal diameter with 20um of wall thickness. The walls are extra thick because there is lots of smooth muscle and they can contract and relax to adjust blood flow through tissue bed and adjust SVR.
Discuss internal diameter vs wall thickness of capillaries
5um internal diameter vs only 1um wall thickness, because theyre only 1 epithelial cell layer thick, and allows for products to exchange between the wall.
If norepinephrine comes in contact with capillaries, what happens?
Nothing. They don’t have smooth muscle to contract and relax.
What vessel has the fastest, and slowest velocity of blood flow?
Aorta, and veins(?, might be capillaries?)
How much total cross-sectional surface area of capillaries?
4500cm2. We dont need to know so much the exact number, but understand the trend.
This is the most surface area of any vessel in the body.
What has more total cross-sectional surface area: Aorta + small arteries + arterioles — OR — Venules, small veins, venae cavae
Venous side, much more.
Arteries have less surface area and higher velocity.
Veins have more surface area and lower velocity.
Delta P of capillary beginning and end
20
Arterial end of the capillary will be called
arteriolar
Venous end of the capillary will be called
venous end
For this class, a normal MAP will be
100mmHg
What is driving flow from one end of the tube to the other?
pressure difference.
Moving fluid from inside of the capillary, to the outside of the capillary, is called?
Filtration, on the arterial end
Moving fluid from outside of the capillary, the inside of the capillary, is called?
Re-absorption
Forces will favor _______ at the arterial end, and will favor _____ at the venous end.
Filtration; re-absorption
the four capillary starling forces are
Pcap (Pc), Pisf (Pif), PIEcap (PIEp), PIEisf (PIEif)
Pcap is also called
Hydrostatic pressure
Capillary pressure
Whats the physical fluid pressure?
Pcap/hydrostatic pressure in capillary/capillary pressure/Pc/hydraulic pressure in capillary
30 arterial end, 10 venous end
Interstitial fluid pressure names
Pif/Pisf/hydrostatic pressure in ISF
Interstitial fluid is
all the fluid outside the vasculature and outside the cells
A high Pif/Pisf around the capillary should do what to filtration and reabsorption?
Oppose filtration and promote reabsorption.
If Pif/Pisf is 10, it will oppose
filtration
In an entirely healthy patient, a normal Pif/Pisf is
negative 3mmHg
Why is Pif/Pisf negative?
Lymphatics pull excess fluid out of interstitium and causes a negative pressure.
If Pif/Pisf is -10, what is happening?
more filtration and less reabsorption
Osmotic effects of dissolved proteins is referring to
Colloid osmotic pressure
If the capillary cell wall is not permeable to blood proteins, but it is permeable to fluid and small molecules, this results in
Plasma colloid osmotic pressure
Plasma colloid osmotic pressure is the long way of saying
plasma oncotic pressure
Oncotic is the same as
plasma osmotic
Plasma colloid osmotic pressure abbreviations are
PIEp and PIEcap
a normal plasma oncotic pressure is
28mmHg
What proteins make up the plasma osmotic pressure
albumin, fibrinogen, immunoglobulin
If we hemorrhage or have liver failure, why does fluid leak out of the vascular system?
We dont have the colloids needed to maintain pressure and keep them in the capillaries.
If we have something that makes the walls of the capillaries more porous than normal?
Vessel loses osmotic pressure
Osmotic pressure is dependent on
a semi-permeable membrane where fluid can move but dissolved substances cant.
Why can’t you just give septic patients albumin?
Primarily, it doesnt matter if cells are permeable to proteins. Secondarily, the capillaries are permeable to the proteins and the albumin can just leak out of the vascular space causing more damage
a reduced PIEp/PIEcap would result in
difficulty in keeping fluid in CV system
PIEisf/PIEif proteins are ____ and what are the names of them
matrix proteins that hangout in ISF.
Largest is Proteoglycan filaments, another large one is Hyaluronic acid, usually dont move in/out of capillary very easy.
Collagen is also present.
PIEisf/PIEif has more or less proteins than PIEp/PIEcap
PIEp/PIEcap has way more
What is the normal pressure for PIEif/Pisf
8mmHg
PIEisf/PIEif will act just a little to _____ fluid movement in the interstitium, but this is _________ by the fact that there is __________ colloids inside the capillary.
favor; outweighed; more
What can cause an increased amount of colloids in the PIEif/PIEisf? why?
trauma, sepsis.
Trauma: If we destroy our cells unplanned, all the stuff within the cell will be scattered into the ISF.
Sepsis: if our capillaries turn into swiss cheese, the colloids within the vessel that arent normally permeable will leak into the ISF.
If we have trauma, whats going to be the fluid shift?
The cells die due to trauma, and release tons of proteins into the ISF, increasing PIEif/PIEisf, which draws fluid into the ISF and causes swelling.
During sepsis, we’ve established that proteins can leak into the ISF. What about when sepsis is corrected, what can we do about the increased proteins in the ISF?
They’re going to continue to be a headache for you because there is no easy way to get them back into the vasculature. Thats why there is swelling and edema.
Eventually, the lymphatics will pick them up, but the rate is very slow, because lymphatics normally just absorn excess fluid. Even slower if the patient is bed bound and not moving around!
the lymphatics job in the ISF
absorb excess fluid out of the ISF
NOT proteins, normally!
What is the only way for the proteins to get back into the plasma?
Through the lymphatic system
What makes the lymphatics work faster?
Moving around! Slower when bed bound
How fast can the lymphatic system pick up the pace?
20-40x faster for fluid! But cant really speed up for proteins, thats super slow.
What are the 2 circulatory systems in the body?
Cardiovascular and lymphatic system!
Surgeons need to know the topography of the _________
lymphatic system
Secondary to all the other pressure factors of the capillaries is the _______ and what is it related to?
Kf
Capillary filtration coefficient!
It’s related to how permeable the capillaries are, more referring to fluid rather than proteins/other compounds. It also takes into account surface area.
3 main proteins that make up the total capillary oncotic pressure
Albumin, globulins, fibrinogen. It totals up to 28mmHg PIEp
Whats the largest capillary protein contributing to overall PIEp pressure?
Albumin, 21.8mmHg
Globulins and fibrinogen contributions to total PIEp pressure are?
Globulins - 6.0mmHg
Fibrinogen - 0.2mmHg
Lymphnodes are
areas of collection of lymphatic system
Where does the lymphatic system empty into?
Via lymphatic ducts at top of thorax, returning it into the CV.
What do one way valves look like for lymphatic system? (insert picture!!!!)
If we increase activity, what will increase?
lymphatic flow
what is the range for lymphatic flow?
1-20+
What do SCDs do?
simulates normal movement of fluids in the leg for a bed bound patient and increases lymphatic flow
What forces contribute to filtration?
PCap/Pc arteriolar end being 30, and Pif/Pisf being -3mmHg, and PIEif/PIEisf being 8mmhg
What forces oppose filtration?
the plasma oncotic pressure (PIEp/PIEcap) of 28mmHg
What is the Net filtration Force/pressure (NFF) on the arteriolar end if all pressures are normal?
Pc of 30+ Pif of 3 (positive 3 even tho its -3) + PIEif of 8 = 41mmHg
subtract PIEp of 28
NFF is 13mmHg
What is the NFF on the venular end if all pressures are normal?
Pc of 10 + Pif of 3 + PIEif of 8 = 21
subtract PIEp of 28
NFF = -7mmHg
NFF of arteriolar end
13mmHg, promoting filtration.
NFF of venular end
-7mmHg, promoting reabsorption.
What is the NFF in the MIDDLE of the capillary vessel?
+3mmHg, possibly.. Idk if he would ask this. But thats the middle of two ends.
If the NFF of the arteriolar end is 13, and the NFF of the venular end is -7.. this seems slightly imbalanced with excess fluid being filtered but not reabsorbed. What corrects that?
lymphatic system absorbs it!
What would you say the NFF of the lymphatic system is?
-6mmHg, possibly. idk if he would ask this. But this is what would balance out the NFF to zero.
What is the net capillary pressure?
You would think its 20, since delta P is 20, and thats halfway between 30 and 10.
But, the net capillary pressure is actually 17.3mmHg.
Why is the net capillary pressure below 20mmHg?
Capillaries get larger as we go from arteriolar end to venular end, so the net capillary pressure leans closer to 10 than 30.
What is the net filtration pressure (NFF/NFP) on average?
0.3mmHg
While this is super low, the amount of capillaries around the body makes that pretty significant, and thats where the lymphatic system comes in.
General Capillaries are most permeable to
water, 1.0
General Capillaries are how permeable to NaCl?
most permeable of all the ions/molecules, 0.96
Openings in between endothelial cells in the capillaries allow
real small molecules like NaCl and water.
Where does NaCl not get in in between epithelial cells?
Blood brain barrier, super tight.
What is least permeable to the capillaries?
Albumin, its huge.
What is the trend for capillary permeability
larger the molecule weight, the less permeable, but this is tissue specific.
MAP of blood pressure going into renal artery is
100mmHg
Why does the renal vein have such a low blood pressure?
It drops as it moves throughout the kidney due to vascular resistance. The pressure is directly related to how much VR.
Afferent arteriole in kidney are located
immediately upstream/infront of glomerular capillaries
Glomerular capillaries
First capillary set in series of 2 capillary beds
What is in front/upstream of afferent arteriole?
Couple larger arteries that split a bunch of times from renal artery
What controls the blood pressure of glomerular capillaries? And what does the pressure determine?
Afferent arterioles, which will end up determining how much filtration we have in glomerular capillaries.
Glomerular capillaries specialized and set up to
have a lot of filtration
GFR is
the rate of fluid from the glomerular capillary bed into a compartment where we can process whats been filtered
The glucose that gets filtered usually
gets reabsorbed cause the body wants to keep it
The afferent arteriole has alot of what?
resistance to control blood flow to glomerular capillaries
What is the blood pressure of glomerular capillaries?
60mmHg on average.
What is the delta P of the afferent arteriole?
40
Why is the blood pressure of the glomerular capillaries 60mmHg on average?
The renal arterial pressure is 100, and it dropped to 60 due to the resistance in the afferent arteriole.
The glomerular capillary is ____ the pressure of a general typical systemic capillary.
twice
the reason that glomerular capillaries have a much higher pressure, is because the body wants to
create more filtration. Higher pressure = higher force of filtration
All of the glomerular capillaries totaled together, will have a total filtration rate of
125mL’s/minute
We don’t filter _____ and ______ in the glomerular capillaries unless something is really wrong.
Red blood cells and large proteins
only small compounds should be getting filtered.
If we have 1000 glomerular capillaries, what is the GFR of each capillary?
0.125mL’s/minute
