cardio 2.2 Flashcards
what is the Ohm equation for flow
Q=DP/R (diastolic pressue, resistance)
how is blood flow driven
pressure differences (gradients)
what is poiseuille’s law
R=8VL/pr^4 V=velocity L - vessel length r= vessel radius p=Pie
what has the greatest infuence on resistence
Radius
define blood pressure
the force with which the blood is pushed against the walls of the blood vessels
why does the blood pressure decrease through the curculation
distance from the heart
systolic pressure
highest amount of pressure reached during ventricular constriction (first sound heard when measuring BP)
Diastolic pressure
minimum amount of pressure just before ventricular ejection begins (last sound when checking blood pressure)
what is the wind kessel effect
Storing of potential energy in the arterial wall to allow a more continuous blood flow as the heart is relaxing (diastolic runoff)
Formula for Mean arterial Pressure and define
pressure that propels blood into tissue (avarage pressure in the cardiac cycle
MAP=2/3 DP + 1/3 SP
what is Total periperal resistance
the sum of all resistance in the vasculature
what are three factors that increase resistance in a single vessel
- blood viscosity
- -vessels length (only constant
- vessel Diameter
what does blood viscosity depend on
- concentration of suspended meduim (formed elements)
- velocity of flow
- radius of the vessel
what occurs in low hematocrit states (ie Anemia)
high state?
viscosity decreases and
vascular resistance decreases
what could the RBC do to increase viscocity
aggregate into stacks called rouleaux formation (thick blood)
how much will the blood flow increase if the vessel dialates twice its radius
16 Fold (4x increase radius = 256 fold increase flow)
what occurs in Venoconstriction
pressure increses more then resistance —->blood flow increases—–>venous return increases
where are bororeceptors placed
in th carotid sinus and aortic arch (measure pressure)
can bororeceptor change to BP
not, they do participate in baroreceptor reflex (tell the body what the blood pressure is)
Baroreceptor communicate with what
CNs IX and X, which carry the signal to the medullarty cardiovasular (aka cardioregulatory) center in the brain
how does the medullary cardiovasular center function
- consist of individual muni-center such and the vasomotor are and cardioinhibitory area
- makes desisions about what to do about hypertension and hypotension
- and then employs services using SNS and ParaNS
what occurs when the blood pressure is to high
deacrease in SNS activity and increase in PNS activity to lower HR
what occurs when the blood pressure is to low
Increase in SNS activity and decrease in PNS activity to rais HR
what occurs to blood pressure when you get out of bed
blood pressure rises
what are the limitation to baroreceptors
Can not correct extreem hypo and hypertension issues
what is a common example of a baroreceptor reflex slowing down
orthostatic hypotension, slow baroreceptor reflex
