Exam 1, kaplan USMLE topics Flashcards
How do you calculate CO
HR x SV
How do you calculate MAP with just BP levels
DBP+ 1/3(SBP-DBP)
what is formula for MAP
CO x TPR
Which level of heart volume is the best representation of preload
EDV
how do we measure increased preload of L ventricle
rise in pulmonary capillary wedge pressure
What is the formula for ejection fraction
SV / EDV
What can cause an increase in afteroload
increased MAP
increased TPR
aortic stenosis
describe effects of increased afterload on SV and ESV
decreased SV
increased ESV
describe changes with CHF on preload
loss of contractility which decreases ejection fraction and so increases preload
describe changes in preload with hemorrhage
decrease preload, lose venous return
SAN responds to increases contractility
what occurs with preload when you lay supine after standing
increased VR will increase performance and CO which inc BP so reflex is decreased SAN and reduced contractility
What is the formula for SV
EDV-ESV
what can cause an increase in ESV
abrnormal reduction in ventricular emptying due to impaired contractility or excessive afterload
what can cause a an decrease in EDV
decrease in ventricular compliance during filling
tissue stiffness or impaired ventricular relaxation
describe the process from which HTN can lead to L ventricular hypertrophy
at the begining the heart just increases contractility, over time preload increases, and decreased CO occurs. The ventricle then starts to hypertrophy to normalize wall tension
how does radius affect the wall tension and ventricular pressure
as radius increases, more wall tension is needed to maintain pressure
how do we calculate blood flow
Change in pressures over capillary bed (MAP-Venous Pressure) divided by Resistance
where is the lowest pressure drop in vasculature of the body
over the arterioles
how does blood viscosity affect resistence and how do we measure that? give clinical examples of dec viscosity and increased
increased viscosity increased Resistance
Hct!!
dec- anemia
inc- polycythemia vera
how does length of a vessel affect R
proprtionate
2x length= 2x resistance
what does a bruit indicate
turbulent flow
what are factors that can increase turbulent flow
increased tube diameter, increased velocity and decreasing blood viscosity
vessel branching and stenosis
how are afterload and CO paired
increased afterload usually causes a decrease in CO
Right atrial Pressure is an indicator of what
preload
