week 8 capillaries Flashcards
what happens at the capillaries
exchange of blood and tissue of gases, nutrients and wastes
what controls the supply to the capillary bed
capillary sphincters
when the capillary beds are closed what does the blood continue to flow through
metarterioles
why are capillaries good for diffusion
- small diffusion distance - thin wall single layer of cell
- large surface area available exchange
- slow blood flow
what happens in solute exchange in the capillaries (diffusion)
moves down conentration gradient active tissue (exercise) increases concentration gradients therefore increasing diffusion
what is bulk flow
the movement of fluid (blood plasma) out of the capillary to create interstitial fluid and then is pulled back in the venous end
filtration = pushing fluid out
absorption = drawing fluid back in
what is capillary hydro-static pressure (CHP)
pressure of the blood flowing into the capillaries
pushes fluid out of the capillaries
what is blood colloid osmotic pressure (BCOP)
due to there being more solutes at venous end in blood then interstitial fluid
osmosis occurs which causes fluid back into the capillaries
what is net filtration pressure
is the difference between capillary hydostatic pressure and blood colloid osmotic pressure
what is the control centre for the cardiovascular system
located in the medulla oblogata
- receive sensory information from baroreceptors which respond to stretch of vessels
where are the baroreceptors
aortic arch
carotid sinuses
what happens if there is a INCREASE in blood pressure what happens to the sympathetic cardiac nerve activity, Sympathetic vasoconstrictor nerve activity, parasympathetic nerve activity
- decrease sympathetic cardiac nerve activity,
- Derease sympathetic vasoconstrictor nerve activity,
- increase parasympathetic nerve activity
what happens if there is a DECREASE in blood pressure what happens to the sympathetic cardiac nerve activity, Sympathetic vasoconstrictor nerve activity, parasympathetic nerve
- INcrease sympathetic cardiac nerve activity,
- INcrease sympathetic vasoconstrictor nerve activity,
- DEcrease parasympathetic nerve activity
what happens when there is a hemorrhage until something happen to lead response of kidneys (part 1)
- hemorrhage occurs
- blood volume decreases
- venous return decreases
- stroke volume then decreases
- cardiac output decreases
- arterial pressure decreases
- firing of baroreceptors in aortic arch and carotid sinus
label diagram haemorrhage part 2 what happens after baroreceptors fire
look at last slide
