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Cardio IV Blood Volume
microcirculation & fluid exchange
21
Physiology
Undergraduate 3
10/13/2014

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Cards

Term
What is the role of capillaries?
Definition
site of exchange of water/nutrients/gases/waste between interstitial fluid and tissues
Term
Where do capillaries receive blood from?
Definition
smallest arterioles and metarterioles
Term
What are metarterioles? Describe their structure/function
Definition
connection between the arteriole & capillary network

-have ring of smooth muscle which can open and close depending on the demands of the tissue
Term
True or False

Density of capillaries is consistent throughout all tissues
Definition
false

it varies depending on the metabolic activity of the tissue
Term
Describe the different diffusion abilities of lipid soluble substances, lipid insoluble molecules and water soluble macromolecules
Definition
Lipid soluble substances e.g. O2, CO2
exchange freely across all membranes

Water/Lipid Insoluble Molecules
most capillaries have pores to allow transfer of Na+, Cl-, glucose, AAs etc.

Water & Water Soluble Macromolecules
-some capillaries are perforated, vesicles fuse to form large gaps allowing these molecules to cross
Term
What is the term for the movement of water & dissolved substances across the capillary walls, towards the interstitial fluid?
Definition
filtration
Term
What is the term for the movement of water & dissolved substances across the capillary walls, toward the intravascular fluid (blood)?
Definition
absorption
Term
What factors affect the bulk flow of fluid between the blood and interstitial fluid?
Definition
-hydrostatic & osmotic pressure
-permeability of the vessel
-size of the diffusion surface
-blood flow
Term
Another term for hydrostatic pressure is....
Definition
filtration pressure
Term
What does hydrostatic pressure do? What is the normal measurement of hydrostatic pressure?
Definition
pushes fluid out of the blood vessel

normally close to 0
Term
Another word for osmotic pressure is....
Definition
oncotic pressure
Term
What generates osmotic pressure?
Definition
large proteins remain in the blood vessel, will encourage water to flow back into the vessel from the interstitium due to the concentration gradient
Term
If hydrostatic pressure is less than osmotic pressure, will fluid move in or out of the vessel?
Definition
in
Term
True or False

Osmotic pressure decreases along the length of the capillary
Definition
False

it remains constant along the length of the capillary
Term
True or False

Hydrostatic pressure is stronger at the first portion of the capillary
Definition
true
Term
What happens to the fluid that has been pumped into the interstitial tissue?
Definition
it will be picked up by the lymphatic system, drained into large veins
Term
What happens if the lymphatic system cannot keep up with draining fluid?
Definition
edema formation (excessive accumulation of fluid in interstitial tissues)
Term
What is the physiological significance of bulk flow?
Definition
stabilizing blood volume using interstitial fluid as a buffer
Term
If protein levels in blood plasma are low, will osmotic pressure be low or high? Will fluid move in or out of the blood vessel?
Definition
osmotic pressure will be low, fluid will move out of the blood vessel into the interstitium
Term
What mechanisms might cause edema? (4)
Definition
-increased hydrostatic pressure
-increased interstitial protein concentration
-decreased oncotic pressure
-obstruction of lymphatic vessels
Term
What effect would right sided heart failure have on venous pressure?
Definition
venous pressure would inrease, increasing hydrostatic pressure in blood vessels, leading to edema
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