5 Flashcards
(61 cards)
what side of the heart goes to pulmonary circulation
right side
what side of the heart goes to systemic circulation
left side
is the CO in both sides of the heart the same
yes sinon accumulation
what are the two main differences entre pulmonary and systemic circulation
Pressure and VASCULAR RESISTANCE
SC requires high pressure to deliver o2 and blood to all organs.
PC not as much bc delivers to both lungs same amount.
SC has high total vascular resistance (flow controlled by arterioles that constrict and dilate)
PC has low total vascular resistance (flow controlled by oxygen)
what is the pressure in the SC and the mean ARTERIOLE pressure
120/80
MAP: 100
what is the pressure in the PC and the mean ARTERIOLE pressure
25/8
15
what are arterioles
small branches of arteries that lead to capillary beds
pressure drops before and after capillary bed. in SC the drop goes from what in artery to what in veins to what in RA to what in RV to what in PC
what does the drop in pressure correspond to
30 in artery –> 10mmHg in vein –> 2 in RA –> 25/0 –> 25/8
drop in pressure corresponds to water effusion to neighbouring tissues
pressure drops before and after capillary bed. in PC the drop goes from what in artery to what in veins to what in LA to what in LV to what in SC
what does the drop in pressure correspond to
12 in artery –> 8mmHg in vein –> 5 in LA –> 120/0 –> 120/80
low drop in pressure bc you don’t want water effusion to leave and enter air chambers.
what’s starlings law of the heart
Force of contraction of ventricle increases w increased end diastolic volume
–> blood will pump out as much blood as is delivered to it by vena cava and atria.
what’s end diastolic volume (EDV)
amount of blood in ventricles before ejection (before systole)
how do ventricles cope with increased EDV according to starlings law
increase diameter and increase force of contraction
what’s preload
degree of stretching of ventricles in diastole
its proportional to end diastolic volume
what’s stroke volume
the volume of blood pumped out by one contraction
what’s cardiac output
the volume of blood pumped out per unit of time
high preload has what implication on EDV
high EDV
high preload has what implication on SV and CO
high SV and high CO
when would EDV be increased
during exercise
what pathology results from too high preload?
heart failure.
limit to starlings law.
if preload keeps increasing above limit, ventricles WEAKEN and heart contractions will eventually start to weaken and CO will fall
same goes for too high atrial pressure, too high EDV too high ED fibre length, too high EDP
so eventually, high EDV –> low SV and low CO and MORE RESIDUAL VOLUME AT THE END OF SYSTOLE
theory underlying starlings law
actin and myosin are the contractile mechanisms of cardiac muscle. At rest they actually overlap.
so upon contraction, the overlap increases
in heart failure there’s no overlap
why is an enlarged heart problematic
if enlarged heart is not corresponding to increased ventricular wall thin¡canes than force of contraction will be reduced bc muscle fibres are stretched to a point where starlings law is no longer applicable.
what kinds of people have bigger hearts
athletes (Nadal)
what’s the normal value for stroke volume
70mL
what’s the normal value for EDV
120 mL
