Circulatory System Flashcards
(51 cards)
What are the three methods of exchange between capillaries and the body cells?
- Diffusion (Concentration)
- Transcytosis (Awkward molecule movement)
- Bulk flow (Pressure gradient)*
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How does the rate of diffusion compare to the rate of bulk flow.
Diffusion is slower due to its delicate and particular nature.
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_________ is usually present in arterial blood in higher concentrations and ________ is usually found in higher concentrations in the interstitial fluid.
Oxygen , Carbon Dioxide
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What qualities of capillaries found in the brain block many substances from passing through the BBB?
- Very tight junctions
- Endothelial cells very closely packed together
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Which parts of the brain lack BBB and allow capillary exchange to occur more freely?
- Hypothalamus
- Pineal gland
- Pituitary gland
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Method of movement used to transport large lipid insoluble molecules across capillary walls.
Transcytosis
- Insulin
- Antibodies
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Passive process by which large amount of fluid moves into and out of capillaries rapidly
Bulk Flow
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What are the two pressure driven mechanisms of Bulk Flow
- Filtration
- Reabsorption
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Pressure driven movement of fluid and solutes from blood within the capillaries into interstitial fluid
Filtration
- Blood hydrostatic pressure (BHP)
- Interstitial fluid osmotic pressure (IFOP)
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Pressure driven movement of fluids and solutes from the interstitial fluid/space into blood
Reabsorption
Blood colloid osmotic pressure (BCOP)
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Balance of the filtration and reabsorption pressures
Net filtration Pressure (NFP)
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What does the NFP measure?
Determines whether volumes of blood and interstitial fluid remain steady or change on BOTH the arterial and venous end of the capillary
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Volume of fluid and solutes reabsorbed is near the volume of fluid and solutes filtered.
Frank Starling’s law of the capillaries
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NFP Formula
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(BHP + IFOP)
Promotes filt.
minus
(BCOP + IFHP)
Promotes reab.
What value will a NFP that promotes filtration have?
S98
Positive
What does a negative NFP promote?
S98
Reabsorption
Pressure blood exerts against blood vessel walls.
“pushes” fluid/certain solutes out of capillaries into interstitial space
S99
Blood Hydrostatic Pressure.
Usually 35mmHg at arterial end
Usually 16mmHg at venous end
Where is fluid pulled due to IFOP?
Out of capillaries into interstitial fluid.
Normally small pressure, 1mmHg
small amounts of protein in interstitial fluid
S#99
“Pull” fluid/certain solutes from interstitial spaces into capillaries
S100
Blood Colloid Osmotic Pressure
Usually 26mmHg
“Pushes” fluid/certain solutes out of interstitial spaces back into capillaries
Interstitial Fluid Hydrostatic Pressure
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What is indicative of a IFHP > 0 mmHg?
Pathological process
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Fluid moves out of capillary and into interstitial spaces
Arterial end
Filtration
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Fluid moves from interstitial fluid into capillaries
Venous end
Reabsorption
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Concerning bulk flow, what percentage of fluids/solutes filtered out of the capillaries are reabsorbed?
On average ~ 85%
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