Moon:

MCAT Biology Tutorial: Blood Pressure & Flow

3 months ago
Moon:

3 months ago
Moon:

$${\bf{Measuring~Blood~Pressure:}}$$ systole: the contraction of the blood vessels, highest pressure diastolic: relaxation of ventricles, lowest pressure flow = (delta P)/R where P = pressure and R is resistance can also use Poiseuille's Law (see hydrostatics tutorial) highest in the aorta and lowest in veins blood does not perfectly follow bernoulli's b/c it's not ideal fluid $${\bf{Regulating~Blood~Pressure:}}$$ - blood pressure must be maintained to exchange nutrients/waste in the capillaries - total peripheral resistance: resistance of the entire circulatory system - changed by changing the output level of the heart & the muscle lining of arterioles - two methods: > baroreceptor reflex (quick). - changes cardiac output and resistance - activates SNS or PNS (depending on whether the pressure needs to be raised or lowered) - uses baroreceptors in arteries > renin-angiotensin-aldosterone: (will refer to this as angiotensin system from now on) - changes volume of plasma - uses mechanoreceptors to signal to kidneys to secrete hormones - renin --> increase blood volume through water intake --> increase in blood pressure

3 months ago
Moon:

$${\bf{Fluid~Exchange~in~the~Capillaries:}}$$ - low overall pressure - two ends of a capillary (arteriole end and venule end) - at arteriole end, hydrostatic pressure is high compared to osmotic, so blood diffuses out - at venule end, the hydrostatic pressure is lower b/c of the fluid that has exited, and now the fluid will flow back into the capillary - throughout this process the osmotic pressure is relatively constant so the exchange is governed by the hydrostatic pressure differential blood is not ideal but can be approximated w/ continuity Q = Av where velocity is inversely proportional to cross-sectional area assuming constant flow

3 months ago
Moon:

Anyway, that's the end of my tutorial, I hope it was a helpful resource. Source material is the 9th Edition ExamKracker's Biology 2 Prep book for the new MCAT

3 months ago