1.4 Regulation of the Cardiovascular System Flashcards
Define cardiac output.
Volume of blood pumped into the aorta.
Define end diastolic volume.
The total volume of either ventricle at the end of diastole.
Define end systolic volume.
The total volume of either ventricle at the end of systole.
Define stroke volume. (Formula if possible)
The volume of blood ejected into the aorta during systole.
SV = EDV - ESV
Ejaction fraction = … / …
Ejection fraction = stroke volume / end diastolic volume
Define venous return.
The volume of blood that comes back to the right atrium.
Cardic output = … x …
Cardiac output = stroke volume x heart rate
What is cardiac output equivalent to?
Cardiac work.
What are muscaranic antagonists?
Molecules that bind to muscarinic cholinergic receptors on myocytes to prevent acetylcholine from binding, increasing the heart rate. (M2)
What are beta-receptor blockers and what is their function?
Molecules that bind to beta adrenergic receptors on myocytes to prevent adrenaline/noradrenaline from binding, decreasing the heart rate. (β1)
Define myocardial contractility.
A measure of force generated by cardiac myocytes.
Which myocytes are innervated by sympathetic and parasympathetic fibres respectively?
Sympathethic - Atrial and ventricular.
Parasympathetic - Atrial.
Name three things that are essential for the heart to pump effectively
Coordinated transmission of excitation.
Coordination of excitation-contraction coupling.
Precise regulation of input-output.
How does the sympathetic system affect ventricular contractility? (What receptors are involved?)
Neurones release noradrenaline which binds to beta adrenergic receptors, increasing contractility.
(The same mechanism as used to increase heart rate)
How does the parasympathetic system affect ventricular contractility?
Neurones release acetylcholine which binds to presynaptic receptors on sympathetic neurones, inhibiting noradrenaline release and decreasing contractility.
