Cardio Physiology Flashcards
role of circulation
-provide nutrients to all cells in an organism
-provide oxygen to all cells
-remove waster products of cell metabolism that are otherwise toxic
-maintain constancy of the internal environment of cells (homeostasis)
what factors are involved in circulation?
-you need carriers to ship out the good stuff and take away the bad stuff
-you need transportation force (aka a pump) to transport this stuff everywhere in the body
-you need a route system you can follow to transport the stuff
-you need to be able to control how much stuff you deliver to your end-users (aka organs and cells)
-you need some way to know that your end users need more of the stuff when they need it and make changes so they get it
-if some of your end users suddenly need a lot of stuff, you need to be able to deliver this to them without compromising the supply of the stuff to others
significance of parallel circuit
-all organs are receiving blood with the same composition
-relative flow to one organ can be adjusted as required without necessarily compromising flow to another
-some organs can withstand having flow lowered far more than others as they serve blood conditioning functions well in excess of their metabolic need
-only organs in series are the heart and lungs —> everything goes through the lungs
carotid baroreceptors
-carotid baroreceptors sit at the base of the brain and they measure strain —> they will trigger the brain to change pressure
-solve cross species problems with this concept since scaling at level of capillaries is the same
example of giraffe baroreceptors
giraffe has head close to the ceiling and heart close to the ground and the heart has to pump against gravity —> generates big pressure
what causes vessels to dilate during exercise?
more CO2 buildup, which leads to acidosis and the pH drops —> a local vasodilator is activated when the chemoreceptors sense the change and trigger response from the brain
what is the one organ that doesn’t dilate with less O2?
lung- block off blood flow to an airway of lung and you ventilate to send blood —> pulmonary vessels constrict to match profusion with ventilation
distribution of blood volume, pressures, resistances and flow rates
-most blood is in veins and very little in arteries
-increase blood volume acutely, constrict veins
-very little blood in capillaries
-in large arteries, the BP is fairly constant
-as you get into smaller arterioles, the resistance increases and the pressure goes down —> speed of flow declines
-if the pressure went down completely, you would have a force to move the blood back up to the heart —> need pressure gradient otherwise blood will pool from gravity
macro hemodynamics
-need a pump to generate flow —> cardiac output
-you have large arteries to transport the blood to the organs (no resistance here)
-you have smaller local arteries in the organs that get small enough to cause resistance to flow
-you have tiny capillaries and by the time the blood gets there, flow is no longer pulsatile and goes much more slowly
-you then regroup at the other end into large veins (minimal resistance) to get it back to the pump
-need compliance of 120/80 —> no flow then you don’t have pressure
relationship between cardiac output, pressure, and vascular resistance
cardiac output = mean blood pressure/vascular resistance
what determines resistance in small arterioles?
-resistance = 8/pi * viscosity * length/radius^4
-every time the radius decreases, the resistance increases
-very sensitive when you get to smaller organs
what can increase the viscosity of blood?
proteins in the plasma can increase the viscosity
multiple myeloma
cancer of the plasma cells that produce abnormal antibodies, or immunoglobulins, and make it harder to push blood through
how can we increase red blood cells
smoking- body produces more red blood cells to compensate for the lack of oxygen and you end up getting big bubbles in the lungs
what allows us to not need a very high blood pressure to get through the resistance?
parallel vessels —> 1/Rtotal = sum of 1/Ri
heart failure
-imbalance of starling’s forces —> water gets trapped in tissues in between and can’t get back into the capillaries
-in radiography, lung should be dark on both sides but in dilated heart failure you see wispy white parts
interstitial edema (pitting edema)
-fluid overload in peripheral tissues since gravity is pooling the fluid
-usually a problem with the ectotic pressure
liver disease
-liver produces albumin, which can decrease the amount of proteins in the blood and water gets trapped
-often you see edema in the belly
renal disease
kidney is a filter and pees out the proteins in your blood
wet sponge lung
space for gas exchange in the capillaries is filled with water and makes it difficult to diffuse gases
acute respiratory distress syndrome (ARDS) from covid-19
-total breakdown of membranes in the lung —> profusion of it leaks into the airways
-in heart failure, you can reduce pressures and move fluid out of lungs but in this the membrane is no longer impermeable and everything gets out
-ventilate a person and blow in O2 but when lungs transfer capacity doesn’t work
-extracorporeal oxygenation- often you have to take out the blood, put it in machine and put O2 in it then put it back in
structure of the heart
-consists of four valves
-blood from the periphery —> goes to the right atrium through the superior and inferior vena cava
-tricupsid valve allows the blood to flow from the right atrium to the right ventricle then to the lungs through the pulmonary valve
-oxygenated blood from lungs goes to the left atrium then the left atrium
-mitral valve connects the left atrium to the left ventricle —> brings oxygenated blood through the aortic valve to the aorta
basic cardiac cycle
- filling phase (diastole)
- start contraction and the valves are all closed still
- continue contraction- valves open and heart ejects into both lungs and arteries
- heart muscle relaxes, valves remain shut
- heart starts filling again
-once you have two chambers without a gradient —> atrium contracts
atrial fibrillation
-chaotic heart rhythm activation pattern with no concerted beating
-atrium is always quivering and individual activation are not getting to the ventricle
-we all experience this, however, those with heart disease, heart failure, hypertension are less tolerable since the atrium has to continue to pump more
