Physiology Flashcards
Cardiac output
Stroke volume x Heart rate
- volume ejected per minute (mL/min)
Stroke volume
Volume ejected in one beat (mL)
Percentage breakdown of cardiac output to specific organ systems
Cerebral = 15%
Coronary = 5%
Skin = 5%
Renal = 25%
GI = 25%
Skeletal muscle = 25%
Fick’s principle
Equation used to calculate cardiac output
O2 consumption/ (o2 pulmonary venous) - (o2 pulmonary arterial)
What circulatory unit is the most abundent?
Capillaries
Veins are second
What circulatory is least abundant?
Aorta and vena cava
Arteries are 2nd
What circulatory unit has the most blood volume in it at anytime?
The veins as a whole
Arteries are 2nd
Where is the largest pressure drop occurring in the circulatory system?
From small arteries -> arterioles
Why do the aorta and arteries have undulating pressures?
Heart beat (systole vs diastole)
- also referred to the pulse pressure
Two phases of cardiac cycle
Systole (contraction)
Diastole (relaxation)
Isovolumetric phase of systole
Phase right before contraction where blood pressure is increasing while ALL valves are closed
Ejection phase of systole
Pressure is high enough to open the pulmonary and aortic semilunar valves and initiate blood ejection.
At the same time, the atria are filling with blood
Isovolumetric phase of diastole
Atria are filling with pressure as all valves are closed
Ventricle filling phase of diastole
Pressure in atria are high enough to open bi/tricuspid valves to fill ventricles
End of diastolic volume (EDV)
Volume in the ventricles during isovolumetric phase of systole
- typically 120 mL but can range
