Exam 3: cardiac output Flashcards
How many phases of cardiac cycle are there?
4 phases
what happens during the first phase of the cardiac cycle?
Ventricular filling
- Blood flows to atria through AV vales and into ventricles
- semilunar valves are closed
- atrial contraction drives more blood inot the ventricles
what happens during the second phase of the cardiac cycle?
isovolumetric contraction
- pressure in the ventricle exceeds in the atria
- AV valves are closed
- pressure isnt great enough to open semilunar valves, no blood flow in or out of ventricles
What generates sound generates the first heart beat?
The AV vales closing
what happens during the third phase of the cardiac cycle?
ventricular ejection
- ventricular pressure rises and blood is pushed though SLV
- ventricular pressure drops, SLV shut
- ends systole
What generates sound generates the second heart beat?
Semilunar valves closing
what happens during the fourth phase of the cardiac cycle?
isovolumertric relaxation
- pressure is still to high to allow AV valves to open also too low to push SLV open
- all valves closed and no blood is moving through the ventricles as they relax
what is diastolic pressure?
the pressure of the aorta is at its min
what is systolic pressure?
as the ventricular pressure rises, the semilunar valves open, aortic pressure rises to its max
what causes the semilunar valves to close?
when ventricular pressure is down, aortic pressure drops but remains higher. The diffrence causes the closure
what does MAP stand for?
mean atrial pressure
what is the equation for MAP?
(SP+ [2xDP]/2)
what happens during the first phase of ventricular volume?
ventricular diastole
ventricular volume is increasing and reaches its max (EDV)
what happens during the second phase of ventricular volume?
ventricular systole
ventricular volume is decreasing and eventually reaches min (ESV)
what is stroke volune?
amount of blood ejected from the ventricle during on heart beat
what is the eqaution from SV
stroke volume= EDV-ESV
how many mL of blood does the heart hold when its relaxed?
130mL
what is cardiac output?
the amount of blood pumped by the heart in one minute
what is the equation for cardiac output
CO= SV x HR
what system is the heart controlled by?
ANS
what do neurons in the sympathetic NS release and what do they bind to?
- epinephrine and norepinephrine which bind to adrenergic recpetors on the pacemaker cells
what do neurons in the parasympathetic NS release and what do they bind to?
- neurons release Acetylcholine which bind to muscurinc cholinergic receptors
what response does to the release of epinephrine cause?
- relaseaed when under stress and increases HR
what response does to the release of thyroid hormone, glucagon, and insulin cause?
- increase force of contraction
