Cardiovascular Regulation Flashcards
Cardiodynamics
The movement and the forces of the heart during contraction
End diastolic volume
the amount of blood within the ventricles after complete relaxation (diastole)
End systolic volume
The amount of blood found within the ventricles (remaining) after a complete contraction
stroke volume
the amount of blood taken away from the heart (pumped) per heartbeat (EDV-ESV)
Ejecton fraction
How much of the blood that is pumped from the heart (precentage) - calculated by SV/ EDV
Preload
the degree of stretching that can be produced by the heart in order to acoomodate the blood during ventricular dialstole. it is directly proportional to the EDV - the higher the preload, the higher the end diastolic volume will be.
Afterload
is the tension created by the ventricular systole - enough to be be able to open the semi lunar valves.
Cardiac output
Stoke volume x heartrate
Stoke volume is dependent on
the end diastolic volume - end systolic volume
What two factors increase the preload? (starlings law)
The venous filling time and the venous return
what does preload do?
increases energy of contraction - more preload, more stronger contraction.
allows stretching of the myocytes to increase the area for the blood to fill the ventricles.
what 3 factors affect the end systolic volume?
The preload - the amount of stretching of the myocytes, allows more volume of blood in which then increases the tension of the myocytes - as more the filling of the ventricles, more myocyte tension generated thus more force of contraction.
The Contractibility - the ability and the force within the left ventricles in order to contract the heart with a certain amount of preload - autonomic intervention and hormones.
The Afterload - the amount of tension created by the contraction, enough to open up the semilunar valves.
what is the pressure in the aorta? what is the pressure in pulmonary artery
Aorta= 80mmHg PA= 20mmHg
what happens if the afterload increases but the preload remains the same?
Stroke volume will decrease as the heart contractions are too rapid to be able to remove all the blood from the atria.
Factors that increase contractility? POSITIVE INOTROPIC AGENTS
Beta adrenergic agonists, neurtotransmitters, sympathetic hormones,
Factors that decrease contractility?
parasymathetic hormones and neurotransmitters, beta blockers, vrampril, calcium channel blockers, muscarininc agonists, increase in pottasium, increase in anoxia or acidosis.
Factors that influence heartrate?
Autonomic regulation, hormones