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Basic property of VEINS
balloon-like, have much lower pressure (than arteries)
they are main STORAGE of blood
blood distribution - 64% in veins
Basic property of CAPILLARIES
How is blood exchanged at capillaries? (what controls movement in/out of capillary)
What solutes can NOT diffuse via capillaries?
*Result is that blood mirrors solute environment (except for proteins)
Basic property of ARTERIES
PRESSURE. they are elastic
Basic property of ARTERIOLES
How to change blood vessel flow?
Q= ΔP / R
- ΔP -- change of pressure
- R --- resistance
- Q-- flow (at a given time)
What direction does pressure go? WHat does it depend on?
- ALWAYS from GREATER to a LOWER pressure!
- Depends on: 1. blood volume 2. size of vessel (structure & tone)
*originates from the heart, pressure drops along the way.
What changes resistance most?
the change in SIZE of the blood vessel (just a small adjustment to radius will increase flow)
IN TERMS OF SOLUTE CONCENTRATION
Arteries reflect what part of the body?
Veins reflect what?
- arteries reflect LUNGS
- arteries=away from the heart
- vein reflect TISSUES
- veins=towards the heart
Describe the two forces of pressure in
"Colloid Osmotic Pressure"
In vessel: the plasma contains many proteins (b/c they can't escape), thus makes plasma hypertonic. THis attracts WATER and PULLS IN. (H20 moves from HYPO TO HYPER regions).
The blood pressure pushes back, PUSHING OUT.
*this does not effect sugar or oxygen levels-- NO EFFECT ON COMPOSITION, just effects fluid distribution
So if BP is higher than COP, then fluid is....
If BP is same at COP....
If COP is higher than BP....
leaking out of vessel (edema)
fluid is oozing in
What does lymphatic capillaries do?
returns excess fluid to circulation
What are baroreceptors?
- sensors located in the blood vessels. neurons that become that is excited by stretch of the blood vessel.
- Thus, increases in the pressure of blood vessel triggers increased action
- potentials and provides information to the central nervous system. This sensory information is used primarily in autonomic reflexes that in turn influence the heart cardiac output and vascular smooth muscle to influence total peripheral resistance
Hypotension will cause increase in _________ stimulation
Hypertension will cause decrease in _________ stimulation
low BP = increased sympathetic system!
high BP = decreased sympathetic system!
kidney's act as a drain, they magically turn blood into urine!
High BP = more _____ than _____
Low BP= less _____
- High BP = More PLASMA THAN URINE
- Low BP= less urine
Low BP= Less urine..... then what gets released?
- Renin is an angiotensin, which causes vasoconstriction (subsequently increases blood pressure b/c constricted vessels increases resistence of blood flow).
- Renin also causes kidneys to retain salt & water (directly via aldosterone)
ΔPressure is controlled by:
- capillary exchange
Resistance is controlled by:
- the tissues according to need, nerve override
- ie vasoconstriction (esp arterioles)
What is the formula for determining blood flow?