Chapter 13 (Part 3) Flashcards
what is the opposite of arterial contraction?
vein smooth muscles contract to increase blood flow rate back to the heart.
why is venous contraction like putting my thumb over a garden hose?
if veins constrict, the same amout of blood delivered by the arteries needs to move faster through the smaller venous diameter
veins serve as a… what?
blood reservoir
which has higher compliance: veins or arteries?
veins
what does higher compliance mean?
can be expanded easier to hold more blood
why do veins have higher compliance than arteries? (2)
- more blood is held in veins than arteries
- veins are more elastic due to thinner walls
name two causes of lower stroke volume / pulse pressure / pulse value
- trauma
- congestive heart failure
why does trauma result in lower pulse value?
blood loss = lower BP = lower pulse value
what causes congestive heart failure?
fluid around the heart limits pumping
what two things influence MAP? and what does MAP even stand for?
Mean Arterial Pressure:
1. CO
2. TPR
what is CO?
cardiac output; how hard your heart is working
what is TPR?
total peripheral resistance;
combination of constriction in one place and dilation in another can result in what?
no change, or even a decrease in TPR
carotid and aortic baroreceptors are…. what kind of receptors?
tonic sensory receptors
name two kinds of tonic sensory receptors
carotid and aortic baroreceptors
where are baroreceptor APs sent, and where is that located?
cardiovascular control center in the medulla oblongata of the brain stem
what is the primary way to change TPR?
depends on radius of peripheral arterioles
vasodilation = decreased TPR
vasoconstriction = increased TPR
what is orthostatic hypotension? how does it lead to lower blood volume?
- when lying flat, blood gets evenly distributed throughout your body
- standing causes blood to pool in lower extremities
- bedrest or zero gravity = blood is evenly distributed all the time = no more blood pooling = greater venous return all the time
- body responds by triggering the kidneys to excrete what is perceived as excess fluid to lower blood volume
why doesn’t MAP increase a lot during light exercise?
because total peripheral resistance decreases
why can a stressed-out life lead to hypertension?
increased CO without a physical need to do so
vasodilation does not occur in muscles
end result is increased TPR
over time, this can lead to high BP
baroreceptors reset to higher baseline BP and treat it as normal rather than respond to try and lower BP
what is the cause of renal failure?
kidney glomeruli ruptured by high BP
why would kidney glomeruli rupture by high BP?
long term hypertension
