2D regulatin of cardiac output via stroke volume Flashcards
what are the three factors effecting stroke volume
preload (frank starling mechanism)
intropism
afterload
what is the frank starling law of the heart
within physiological limits, the more the ventricles are filled during diastole, the more blood they will eject during systole
what is preload
the stretch on the ventricular cardiac muscle before it contracts
what is heterometric regulation
the controle of SV with preload
what heart will have a greater cariac contractility (inotropism)
positive inotropic effect (increased contractility of results in more complete ejection of blood)
list the rout by which cardiac contractility proceeds
SNS stimulation bie Beta1 receptors —> incresese the force of contraction by by 2 mechanisms
what are the two mechanisms that SNS stimulation via beta1 receptores induces
- increases the inward Ca+ during plateau phase
- increases the activity of the SERCA pumps (more Ca+ is accumulated by the SR and more Ca+can be used on the next stroke
what is afterload
the load the heart must overcome after (and while) it contacts (back pressure on aoric and pulmonary semilunar valves)
what happens when afterload increases
ventricles must pump blood against a higher pressure, results in a lower stroke volume
when afterloads decreases
pumps blood against a lower pressure, resulting in and increased stroke volume
what are some examples of increased afterloads
- vasoconstriction
- increased blood volume of viscosity
what is normally used to treat afterloads
vasodialators
cardiac output or perfomance is inhanced by
- increased preload
- increased inotropy
- increased heart rate
- deacreasing afterload
what depresses cardiac output
decreased preload
-decreased inotropy
-decreased heart rate
increased afterload
