Term
| What is the role of capillaries? |
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Definition
| site of exchange of water/nutrients/gases/waste between interstitial fluid and tissues |
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Term
| Where do capillaries receive blood from? |
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Definition
| smallest arterioles and metarterioles |
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Term
| What are metarterioles? Describe their structure/function |
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Definition
connection between the arteriole & capillary network
-have ring of smooth muscle which can open and close depending on the demands of the tissue |
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Term
True or False
Density of capillaries is consistent throughout all tissues |
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Definition
false
it varies depending on the metabolic activity of the tissue |
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Term
| Describe the different diffusion abilities of lipid soluble substances, lipid insoluble molecules and water soluble macromolecules |
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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 |
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Term
| What is the term for the movement of water & dissolved substances across the capillary walls, towards the interstitial fluid? |
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Definition
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Term
| What is the term for the movement of water & dissolved substances across the capillary walls, toward the intravascular fluid (blood)? |
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Definition
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Term
| What factors affect the bulk flow of fluid between the blood and interstitial fluid? |
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Definition
-hydrostatic & osmotic pressure
-permeability of the vessel
-size of the diffusion surface
-blood flow |
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Term
| Another term for hydrostatic pressure is.... |
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Definition
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Term
| What does hydrostatic pressure do? What is the normal measurement of hydrostatic pressure? |
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Definition
pushes fluid out of the blood vessel
normally close to 0 |
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Term
| Another word for osmotic pressure is.... |
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Definition
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Term
| What generates osmotic pressure? |
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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 |
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Term
| If hydrostatic pressure is less than osmotic pressure, will fluid move in or out of the vessel? |
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Definition
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Term
True or False
Osmotic pressure decreases along the length of the capillary |
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Definition
False
it remains constant along the length of the capillary |
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Term
True or False
Hydrostatic pressure is stronger at the first portion of the capillary |
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Definition
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Term
| What happens to the fluid that has been pumped into the interstitial tissue? |
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Definition
| it will be picked up by the lymphatic system, drained into large veins |
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Term
| What happens if the lymphatic system cannot keep up with draining fluid? |
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Definition
| edema formation (excessive accumulation of fluid in interstitial tissues) |
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Term
| What is the physiological significance of bulk flow? |
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Definition
| stabilizing blood volume using interstitial fluid as a buffer |
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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? |
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Definition
| osmotic pressure will be low, fluid will move out of the blood vessel into the interstitium |
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Term
| What mechanisms might cause edema? (4) |
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Definition
-increased hydrostatic pressure
-increased interstitial protein concentration
-decreased oncotic pressure
-obstruction of lymphatic vessels |
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Term
| What effect would right sided heart failure have on venous pressure? |
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Definition
| venous pressure would inrease, increasing hydrostatic pressure in blood vessels, leading to edema |
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