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Phys2 Card&Vasc Fnc

Phys2 Car&Vas Fnc

QuestionAnswer
Equation for mean arterial pressure (MAP) MAP = DP + 1/3(Pulse pressure) **Pulse pressure is SP-DP
Ohm's Law and how it applies to CO? E=IR, or I=E/R. CO (I)= Paorta-Pra (E)/TPR (R). **Since Pressure in R atria is negligable, CO=Paorta/TPR
What is the equation for Aortic Pressure (AP or MAP)? AP = CO X TPR **SVR (systemic vascular resistance) and PVR (peripheral vascular resistance) are often used instead of TPR.
Where would you find BL vessels with high density of B2 receptors? what will happen there in response to Symp? 1.Liver. 2.Skeletal muscle. 3.coronary. 4.Cerebral. **They will cause vasodilation due to Epi released from chromaffin cells in the adrenal medulla.
2 ways parasympathetics can stimulate BL vessels? 1.Direct: Cause endothelial cell to release NO into smooth muscle causing vasodilation (occurs in: salivary glands, GI, erectile tissue). 2.Indirect:ACh binds to M2 receptors on postsynaptic adrenergic neurons (symp) and prevent NE release.
Do veins contribute to MAP? NO
Do veins contribute to Preload? YES
Do veins contribute to EDV? YES
What type of receptors to veins have? Alpha1. NE binds here and makes floppy veins taut to help increase the rate of venous return to the heart and thus Inc preload.
Can an arteriole dilate/relax even in the presence of NE binding to A1 receptors? Yes, either with a higher percentage of B2 receptors responding to Epi, OR vasodilator metabolites (dec O2, Inc CO2, Acidosis)
Are veins more compliant than arteries? YES, 20x more compliant.
What all is included in the Central BL volume? (holds 20-25% of BV) 1. Superior (central) Vena Cava. 2.Intrathoracic portion of Inf vena Cava. 3.R Atrium. 4.R Ventricle. 5.Pulmonary arteries and veins. 6.L Atrium.
What are the ONLY 2 ways to alter Central BV? 1.change total BV. 2.Redistribute BV.
3 Ways to increase total BV 1.Infuse Fluid. 2.Retain Na+ and thus water. 3.Shift fluid from interstitial into plasma (Increase COP or THP).
3 ways to decrease total BV 1.Hemorrhage. 2.Sweat. 3.Shift fluid from plasma into interstitium (Inc CHP or TOP).
How does Right Atrial Pressure (Pra) effect VR (venous return) and CO? Pra determines VR because the lower the pressure, the more BL that will move into the right atria and thus the more BL that will be able to contribute to SV. **Pra and VR are INVERSELY related
How does CO effect Right Atrial Pressure (Pra)? CO directly effects Pra b/c the higher the CO, the more BV removed from the heart, and the greater the pressure change experienced in the Right atrium, pulling more BL out of it.
Why are Pra and VR inversely related? b/c VR is dependent on the driving force pushing BL into the right atria (remember bp in veins is minimal). If the Pra is NOT negligable as it usually is, it will decrease the driving force and thus VR into the R atrium.
What is Pmc? mean circulatory filling pressure. It measures the Pra when CO is 0, measures the "Fullness of the system" **usually 7mmHg.
At what pressure does CO and VR not affect Pra? 2mmHg
What happens to VR and CO as Pra Increases above 2mmHg? Decrease linearly on the vascular function curve.
What happens to VR and CO as Pra Decreases from 10mmHg? Increase linearly until 2mmHg on the vascular function curve.
At what Pra is CO and VR the highest? 2mmHg
What happens to Pra as CO Increase? DECREASES b/c it is pulling more BL out of the right atrium
What 3 things affect the Vascular Function Curve? 1.BV (will determine the Pmc, Inc will raise line upwards due to higher Pmc). 2.VT the system (how tight). 3.TPR or SVR (changes the slope of the curve.
What causes a parallel upward shift in the venous fnc curve? 1.Inc Vol. 2.Inc VT (sympathetic activation of veins, making them taut. ALSO, external muscular compression).
What causes a parallel downward shift in the venous fnc curve? 1.Dec Vol. 2.Dec VT (Less sympathetic inflow. ALSO, less external muscular compression).
Does Pmc change with Vol & VT changes? YES. It is directly related in that it increases when they increase, and decrease when they decrease.
How can BV be increaseed? 1.Inc COP>CHP (pulls fluid from interstitium into the plasma). 2.Kidney's retention of Na+ and water (antidiuretic). 3.Transfusion (directly adds fluid into plasma).
How can BV be decreased? 1.Diuretics (Kidney excretes Na+ and thus more water). 2.Hemorrhage (BL loss). 3.Diarrhea (cha cha cha). 4.Vomitting. 5.Excess sweating.
If a patient was hemorrhaging, what would happen to their Pmc? CO? Both would DECREASE
If Pra is 2mmHg, what is VR? 5L/min in a normal patient.
What would cause an INCREASE in SLOPE of venous function curve? 1.Decreasing SVR/TPR (decreased sympathetic tone to arterioles). This will Inc CO & VR for a given Pra. **Dec SVR/TPR is the same as VASODILATION
What would case a decrease in SLOPE of venous function curve? Inc in SVR/TPR (Increased sympathetic inflow and tone). This will Dec CO & VR for a given Pra. **Inc SVR/TPR is same as VASOCONSTRICTION
For a given Pra, how will Inc Vol and VT affect CO and VR? INCREASES
For a given Pra, how will Dec Vol and VT affect CO and VR? DECREASES
with Inc/Dec arteriole resistance (SVR or TPR), does Pmc change? NOOOO. You aren't changing the BV at all so the "fullness" at 0 CO is the same.
4 possible changes seen to vascular function curve? 1.Parallel shift upwards: Inc Vol & VR. 2.Parallel shift downwards: Dec Vol & VR. 3.Increase slope: Dec SVR/TPR (vasodilate). 4.Decrease slope: Inc SVR/TPR (vasoconstrict).
On the Frank Starling/ Cardiac function curve, what value is interchangable with Pra? Ventricular Filling Pressure (mmHg).
What would Enhance cardiac function curve? 1.Dec Afterload (dec MAP). 2.Inc Inotropy. 3.Inc HR. **Both 2&3 are direct symp responses, however symp contradict 1, but the graph is more sensitive to 2&3.
What would depress the cardiac function curve? 1.Inc Afterload (inc MAP). 2.Dec Inotropy. 3.Dec HR.
What happens when the venous function curve and cardiac function curves intersect? does this always happen? The CO=VR. YES this will always happen somewhere along the two lines (changes if either curve is altered)
What effect will exercise have on the equilibrium point of the venous and cardiac function curves? At the same Pra, you get a much higher CO: 1.Inc HR and Inotropy will enhance cardiac curve. 2.Inc VT (inc symp tone) will shift venous curve parallel upwards. 3.Vasodilation (Dec SVR/TPR) due to metabolites (inc CO2 & H+) will inc slope of venous curv
What effect will HF have on the equilibrium point of the venous and cardiac function curves? Compenstion: 1.Depression of cardiac curve immediately (less inotropy b/c tissue is dead). 2.Intial compensation: Inc Vol & VT parallel shifts venous curve upwards. 3.Vasoconstriction (Inc SVR/TPR) will decrease venous curve slope. **2&3 work to rai
What will happen in a patient with heart failure as a result of the compensatory mechanisms that raise CO? Pra with increase drastically. Could lead to HTN
What effect will a hemorrhage have on the equilibrium point of the venous and cardiac function curves? 1.Dec Vol will parallel shift venous curve down. 2.Inc inotropy and HR (inc symp) enhances the cardiac curve. 3.Inc VT (inc symp) parallel raises venous curve. 4.Vasoconstriction (Inc SVR/TPR due to symp) will dec slope of venous curve
Created by: WeeG