Blood flow (exam 3) Flashcards
(41 cards)
BP should linearly inc. with inc. work loads, but if it’s not behaving correctly, when do u stop exercise?
if systolic decreases by 20 mmHG
or if diastolic inc. by 10 mmHG
formula for BP/ MAP
BP= Q (SVxHR) x TPR
does Max BP change with training?
no, ur max is ur max
Nervous control of BP: long term solution
kidneys and fluid balance (through blood volume)
Nervous control of BP: short term
CV system (HR slows or speeds up to control BP)
what role do the atria play in controling BP?
stretch receptors in the atria (barroreceptors-mechanical stretch), detect stretch in atria walls due to inc. blood volume and they signal the brain, whoa hello too much volume/pressure here, so the brain triggers vasodilation in the vv of the legs to decrease the amount coming back to the heart to fast while simultaneously inc. ADH release to make sure it doesn’t decrease too much all at once.
what does the vasomotor center of the medulla do?
uses a pressor and depressor to regulate BP
where does the vasomotor sensor receive stim. from?
input from sensors all over the body (chemoreceptors, baroreceptors, mm afferent receptors) and from cortex and hypothalamus
what does stim of the pressors/ depressors do?
pressor- inc. HR and force of contraction, constricts vascular smooth mm in arterioles and what little their is in vv
depressor= exact opp. of all that- dec. HR, dec. force of contraction, vasodilates, etc.
what happens to end diastolic filling with age?
it decreases
define velocity
rate, speed at which blood is traveling
define flow
volume, amount of blood/time
types of flow
laminar- linear, smooth
turbulent- bubbly, going all diff. directions (happens at divergences,tears/flaps in vessel walls, plaques)
Darcy’s law
Q (flow this time)= [(P1-P2)/R]
what vessels have the lowest velocity of flow in order to allow for blood product exchange between them and their target tissues?
capillaries
in what vessels is vascular resistance highest?
arterioles (tiny holes, makes cells get down to one lane, and they have mm walls- think traffic going from three lane highway to one lane walled off bc of construction)
what is defined as the total vascular resistance from the aorta to the R atrium
TPR
what vessels have lowest vascular resistance to flow?
veins
velocity of flow is _______ proportional to the cross sectional area of the vessel
inversely (think, big pipe= flows slower, tiny pipe= must flow faster)
if length of tube doubles, what happens to flow?
decreases by 50% (duh, can now only move halfway thru in the same amount of time)
if tube radius doubles, what happens to flow?
increases 16 fold! (pouring a gallon of milk through a PVC pipe or through a drinking straw)
if viscosity of the liquid doubles, what happens to flow?
it decreases by half (think pouring water through a funnel or pouring honey through the same funnel)
where is blood flow the fastest? when does this principal become a problem?
fastest in center of vessel bc encounters no resistance there, around the sides of the vessel it has friction from the vessel walls. this becomes problematic if vessels aren’t elastic enough (due to connective tissue disorders like marfan’s syndrome, or due to plaque buildup) to vasodilate when pressure is too great and they tear or break
what does the shearing forces of the blood friction on the vessel walls trigger to be releases?
nitric oxide–>tells brain to vasodilate
