Cardiovascular - Physiology Flashcards
What is the equation for cardiac output?
Stroke Volume(SV) * Heart Rate(HR)
What is Fick’s Law(Equation)
CO = rate of O2 consumption/(arterial O2 content - venous O2 content)
What is the equation for mean arterial pressure?
MAP = 2/3rd diastolic pressure + 1/3rd systolic pressure
What is the equation for pulse pressure?
systolic pressure - diastolic pressure
What is the relationship between pulse pressure and stroke volume?
directly proportional
What is the relationship between pulse pressure and arterial compliance?
inversely proportional
What is the equation for stroke volume (SV)?
EDV - ESV
During the early stages of exercise, CO is maintained by what physiological factors?(2 points)
stroke volume and heart rate
During the late stages of exercise, CO is maintained by what physiological factors?(2 points)
Increased HR
Why doesn’t stroke volume maintain the CO during late stage of exercise?
The SV plateaus
How is the time for diastole affected with increased heart rate?
diastole is shortened
How does increased heart rate affect the filling time during diastole?
It decreases the filling time
Diastole is preferentially shortened with increase HR; which leads to less filling time. How does this affect CO? What type of phenomena could cause this?
There is a decrease in Cardiac Output. Ventricular tachycardia
How is pulse pressure affected in hyperthyroidism?
increased pulse pressure
How is pulse pressure affected with aortic regurgitation?
increased pulse pressure
How does arteriosclerosis affect pulse pressure?
it increases
How does obstructive sleep apnea affect pulse pressure?
increase pulse pressure
How does exercise affect pulse pressure?
increase pulse pressure but transiently
How does aortic stenosis affect pulse pressure?
decreases pulse pressure
How does cardiogenic shock affect pulse pressure?
decreases pulse pressure
How does cardiac tamponade affect pulse pressure?
decreases pulse pressure
How dose advanced heart failure affect pulse pressure?
decreases pulse pressure
What does the nemonic SV CAP tell you?
There is increased stroke volume with increase contracility, decreased afterload and increased preload
How do catecholamines affect contractility?
Catecholamines increase contractility and stroke volume
How do catecholamines increse stroke volume and contractility?(general mechanism)
increased activty of Ca2+ pump in sacroplasmic reticulum)
How does an increase in intracellular Ca2+ affect contractility?
it increases contractility
How does increased activity of the Na+/Ca2+ affected contractility?
The sodium calcium antiport removes calcium from the cell, therefore, decreasesing contractility. Decrease activty of this antiport is going to increase the intracellular calcium levels promoting more calcium and troponin interactions leading to increase contractility
Why does decreased extracellular sodium increase contractility?
It decreases the activy of the sodium/calcium exchange. which results in an increase of intracellular calcium
What is the main mechanism of action of digitalis?(4 points)
it blocks the sodium potassium pump leading to an increase in intracellular sodium leading to a decrease in the sodium/calclium exchange leading to a intrease in the intracellular calcium leading to an increase in contractility and SV
How does digitalis affect contractility?
it increases contractility
How is contratility affected with β-blockers?
decreased
Why do β-blockers result in a decrease in contractility and stroke volume?
β-adrenergic receptors are coupled to Gs proteins which activate adenylate cycle to form cAMP from ATP. Increase in cAMP activates PKA that phosphorylates L-type calcium channels, which causes incrase calcium enry into the cell. Therefore increase contractility. Inhibiting this process is going to decease contractility.
How do catecholamines affect stoke volume
increase
How does an increase in intracellular Ca2+ affect stoke volume?
increase
How does increased activity of the Na+/Ca2+ affected contractility?
It’s going to decrase contractility. The sodium calcium antiport removes calcium from the cell, therefore, decreasesing contractility. Decrease activty of this antiport is going to increase the intracellular calcium levels promoting more calcium and troponin interactions leading to increase SV
How does decrease extracellular sodium affect SV?
increases stroke volume
Why does increase intracellular sodium increase contractility and SV?
it decreases the activity of the sodium/calcium exchange which increases the intracellular calcium
Why does decrease extracellular sodium increase contractility?
Decrease extracellular sodium decreases the activity of the sodium calcium exchange which increases the activity of the intracelular calcium ion which induces calcium induced calmodulin release which increases muscle contractility
How does decreased extracellular sodium affect contractility?
increases contractility
How does digitalis affect SV?
increases it
How is stroke volume affected with β-blockers?
It decreases stroke volume
How do β-blockers affect contractility?
decreases it
Why do β-blockers decrease contractility?
The βlockers decrease the synthesis of cAMP. cAMP activate protein kinase A. PKA phospharlyates the L-type cacium channels, which casues increase calcium entry into the cell.
Why do β-blockers decrease contractility?
The βlockers decrease the synthesis of cAMP. cAMP activate protein kinase A. PKA phospharlyates the L-type cacium channels, which casues increase calcium entry into the cell.
How does heart failure with systolic dysfunction affect contractility?
decreases it
How does heart failure with systolic dysfunction affect SV?
decrease
How does acidosis affect SV?
decrease
How does acidosis affect contractility?
decrease
How does hypoxia/hypercapnea affect contractility?
decrease
How does hypoxia/hypercapnea affect SV?
decrease
How does nonhydropyridine calcium channel blockers affect contractility?
decrease
How does nonhydropyridine calcium channel blockers affect SV?
decrease
Preload is approximated by what type of volume?
EDV
Preload depends on what?(2 points)
Preload depends on venous tone and circuating blood volume
How do VEnodilators affect preload?
they decraese preload
What is an example of a venodilator?
nitroglycerin
The afterload is approximated by what?
MAP
What does Laplace’s law relate?( 2 points)
Left Ventricular Size and afterload
What is Laplace’s Law?
Pressure * Radius/(2* Wall Thickness)
How does the left ventricular wall compensate for increase afterload?(2 points)
increased thickening of the left ventricular wall in an effort to decrease the wall tension
What type of drug is hydralazine?
vasodilator
How does ACE inhibitos and ARBS affect preload and afterload?
They decrease preload and afterload
How does chronic hypertension lead to increase Left Ventricular hypertrophy?
it increases MAP
How does chronic hypertension affect MAP?
It increases it
What is the equation(s) for Ejection Fraction?(2 points)
SV/EDV = (EDV - ESV)/EDV
Left ventricular EF is an index of what?
ventricular contractility
What is the normal value for the EF?
It is much greater than 55%
How is the ejection fraction affected in systolic heart failure?
there is a decrease in the ejection fraction
Is the EF normal or abnormla in systolic heart failure?
abnormal
Is the EF normal or abnormal in diastolic heart failure?
normal
How is SV affected during anxiety?
It is increasd during anxiety
How is SV affected during exercise?
increased
How is SV affected during pregnancy?
increased
A failing heart has what affect on SV?
decrease
What type of dysfucntion of the heart do you see in heat faiulre?
systolic and diastolic dysfunction
The myocardal O2 demands is increased with what?(4 points)
increased afterload, increased heart rate, increase contractility, increae in ventricular diamter(increase in wall tension)
How does an increase in the afterload affect the myocardial oxygen demand?
increase
How does an increase in the ventricular wall diameter affect the myocardial oxygen demand?
increase
How does an increase in contactility affect the myocardial oxygen demand?
increase
What is the relationship between force of contraction and end diastolic length of cardiac muscle fiber?
proportional
How does digoxin affect contractility?
it increases contarctility
A loss of myocardium affect contractility in what manner? What is an example of a phenomena that causes this?
decreases contractility. An example is a myocardial infarction
What is Ohm’s Law?
ΔV = IR
What is Ohm’s law in the cardiovascular system?
ΔP = Q*R
What is the equation for Resistance in the cardiovascular system?
(ΔP)/Q = 8ηL/πr4
What is the total resistance of vessels in series?
TR = R1 + R2 + R3+…
What is the total resistance of vessesls in parallel?
1/TR = 1/R1 + 1/R2 + 1/R3…
The viscosity of blood mainly depends on what?
the hematocrit
How does blood viscosity change with polycythemia?
increases
How does blood viscosity change with hyperproteinemic states? What is an example of a disease state that is hyperproteinemic?
The blood viscoity incresaes. Multiple Myeloma is one example
How does aHereditary spherocytosis affect blood viscosity?
It increases blood viscosity
How does anemia affect blood viscosity?
It decreses blood viscosity
An increase in RA pressure has what affect on CO?
increase
What is the relationship between RA pressure and preload?
they’re synonomous
An increase in EDV has what affect on venous return?
It decreases venous return
What is a example of something that cause negative inotropy?(2 points)
drug overdose or uncompensated heart failure
When consider the venous function curve, the mean systemic pressure is what value on the cruve?
x-intercept
When considering the venous function curve, the mean systemic pressure changes with what?
it changes with the circulating volume/venous tone
What are examples of things that can cause an increase in venous tone or circulating volume?(2 points)
fluid infusion or sympathetic activity
What are examples of things that can cause a decrease in circulating volume/venous tone?(2 points)
Acute hemorrhage or spinal anesthesia
How does a change in the total peripheral resistance affect the mean systemic pressure?
no change
How does a change in the inotropy affect the venous function curve?
no change
What are vasopressors?
they’re anti-hypotensive agents that act to raise reduced blood pressure
What is an example of something that could increase the total peripheral resistance?(drug group)
vasopressors
What can cause a decrease in the total peripheral resistance?
exercise or an AV shunt
During exercise, how does inotropy and TPR change to maximize CO?
There is an increase in inotropy and a decrease in TPR
During compensatory heart failure, what does the body genreally due when considering the vasculature and circulating blood volume?(2 points)
there is an increase in preload and an increae in fluid rention to retain the CO
1: isovolumetric contraction; 2: systolic ejection; 3: isovolumetric relaxation; 4: rapid filling; 5: reduced filling
period between aortic valve opening and closing
systolic ejection
period just before mitral valve close
reduced filling
period between mitral valve closing and aortic valve opening; period of highest O2 consumption
isovolumetric contraction