Heart details Flashcards
CO and right atrial pressure relationship
-increase in venous return -> increase right atrial pressure (to a point), end-diastolic volume and end-diastolic fiber length
-Increases in end-diastolic fiber length -> increases CO
-volume of blood leaving the LV (cardiac output) = the volume it receives in venous return
-*more venous return -> more pressure in right atrium since more blood is accumulating
-too much pressure in right atrium -> pressure gradient that drives venous blood into right atrium is decreased
-Decreased pressure gradient = less venous return to the right atrium
mean arterial pressure
-pressure that would be measured throughout the cardiovascular system if the heart were stopped
-2 factors that influence MAP- blood volume and distribution of blood between stressed and unstressed volume
stressed vs unstressed
-Unstressed: volume of blood in the VEINS; volume that produces no pressure
-Stressed: volume in the arteries; volume that produces pressure by stretching elastic fibers in blood vessels
-When blood volume is 0-4 L -> all blood in the unstressed volume (the veins) -> producing no pressure -> MAP = 0
-When the blood volume is greater than 4 L -> some blood will be in stressed volume (the arteries) -> produce pressure
-when blood volume increases past 4 L unstressed volume remains the same (max) -> stressed increases
-Redistribution of blood -> changes MAP
-decrease in venous compliance= venoconstriction= the veins can hold less blood= blood shifts from the unstressed to stressed volume= increase cardiac output= increase in right atrial pressure
-increase in venous compliance= venodilation= the veins can hold more blood= blood shifts from stressed to UNSTRESSED volume= decrease cardiac output= decrease right atrial pressure
total peripheral resistance
-total blood volume is unchanged during shift of blood -> but it increases the mean systemic pressure and the vascular curve shifts to the right
-If there is venodilation -> unstressed volume will increase -> stressed volume and mean systemic pressure will decrease and the vascular curve shifts to the left
-decrease in TPR= easier for blood to flow from arteries to veins
-Decrease in atrial pressure= decrease in afterload
-Decrease in TPR= increased venous return= increases atrial pressure (increase flow back into the heart
-**The higher the right atrial pressure, the higher the cardiac output
-increase in TPR= more difficult for blood flow from arteries to veins
positive ionotropic agents
-increase in contractility, increase in stroke volume, and increase in CO for any level of right atrial pressure
-CO is increased and right atrial pressure is decreased-> more blood is leaving the heart on each beat due to the increased contractility and increased SV -> less pressure in the atrium
negative ionotropic agents
-decrease in contractility and a decrease in CO for any level of right atrial pressure
-CO is decreased and right atrial pressure is increased-> less output= more pressure
-less blood is leaving the heart on each beat, due to decreased contractility and decreased stroke volume
effects of increase/decrease of blood volume
-Increase in blood volume -> increase in amount of blood in stressed volume (arteries) -> increase the mean systemic pressure -> shifts the curve right in a parallel manner (right means increase in right atrial pressure) -> CO increased and right atrial pressure is increased
-Decrease in blood volume -> decreases the amount of blood in the stressed volume and mean systemic pressure -> vascular function curve is shifted to the left in a parallel manner -> CO is decreased and right atrial pressure is decreased
effects of changes in venous compliance
-Decreases in venous compliance -> shift of blood out of unstressed and into stressed volume -> increase mean systemic pressure -> shifts the curve right in a parallel manner (right means increase in right atrial pressure) -> CO increased and right atrial pressure is increased
-increases in venous compliance -> shift of blood into the unstressed -> decrease mean systemic pressure -> vascular function curve is shifted to the left in a parallel manner -> CO is decreased and right atrial pressure is decreased
increase/decrease TPR
-increase in TPR -> restricting flow of blood out of arteries -> increase in BP and decrease in venous return
-BP increase bc resistance is “holding” blood in arteries -> increases pressure
-increase in afterload (arterial blood pressure) -> decrease CO
-decrease venous return
-Decreases TPR -> decrease arterial pressure -> decrease in afterload -> increase venous return -> increases CO -> decreases right atrial pressure (more blood is pumped out of the heart)
-decrease in TPR increases venous return, which increases right atrial pressure (increased flow back to the heart)
-Depending on relative magnitude of the effects, right atrial pressure can be slightly increased, slightly decreased, or unchanged.
starling
-know everything
-know all laws -> finks, etc.
how much blood in your system
-5L
-1 L of blood loss -> no BP -> heart has no blood
-stressed volume is 0 -> unstressed has 4 L
-volume depleted -> baroreceptors alerted -> HR and contractility is higher -> hearts trying harder (BP might not be high bc ur depleted still
-volume depleted -> kidneys alerted -> renin angiotensin system (anti-diuretic) -> increase volume -> increase Na retention -> water follows -> compensation
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baroreceptors and aortic arch receptors
-sinus baroreceptors -> glossopharyngeal gives feedback to increase parasympathetic tone -> HR slow
-aortic arch only looks at if your hypertensive (baroreceptors detect low and high pressure)
-aortic arch -> CN X -> slows cardiac accelerator + vasodilation -> slows HR, contractility, decrease pressure in arteries and veins
kidney BP regulation
-ACE inhibiotor - angiotensin 2 blocker -> decrease BP
-increase aldosterone -> increase Na reabsorption -> increase ECF volume
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starlings force - cont.
-capillary permeability
-closed loop circuit system
-hydrostatic pressure- arterial pressure at capillary bed
-osmotic pressure- protein at level of capillary
-net filtration- pressure in
-remaining fluid- lymphatic drainage
increase capillary hydrostatic pressure
-arteriolar dilation
-venous constriction
-increased venous pressure
-heart failure
-extracellular fluid volume expansion
