17.5 Cardiac Output and Regulation Flashcards
What is cardiac output? How can it be calculated?
Cardiac output is the amount of blood pumped out by each ventricle in 1 minute.
It is equal to the heart rate multiplied by the stroke volume.
CO = HR x SV
What is stroke volume? How can it be calculated?
Stroke volume is the amount of blood ejected from the right or left ventricle with each beat, and is equal to the end diastolic volume* minus the end systolic volume*.
SV = EDV - ESV
What are the three factors that stroke volume is determined by?
Stroke volume is determined by
- preload, the degree of stretch imposed on the cardiac muscle cells;
- contractility, the effectiveness with which the heart pumps;
- afterload, the force against which the ventricles must pump.
Heart rate is influenced by _____________ such as the ____ and _______ system.
Heart rate is influenced by chronotropic agents such as the ANS and endocrine system.
Cardiac output is regulated primarily by _________ and ________
Cardiac output is regulated primarily by the endocrine and nervous systems.
The endocrine system releases chronotropic and inotropic hormones, and other hormones that regulate water balance and preload.
Epinephrine and norepinephrine are positive ________ and _______ agents.
Epinephrine and norepinephrine are positive chronotropic and inotropic agents.
Acetylcholine is primarily a ______ ______agent.
Acetylcholine is primarily a negative chronotropic agent.
What largely determines preload?
end-diastolic volume (EDV)
Inotropic agents affect:
M/C
contractility.
depolarization.
stroke volume.
heart rate.
Inotropic agents affect:
contractility.
depolarization.
stroke volume.
heart rate.
Which hormone decreases cardiac output by decreasing blood volume and preload?
antidiuretic hormone
atrial natriuretic peptide
aldosterone
norepinephrine
Which hormone decreases cardiac output by decreasing blood volume and preload?
antidiuretic hormone
atrial natriuretic peptide
aldosterone
norepinephrine
