Preload	The amount of blood entering the ventricles when they are relaxed
Afterload	The pressure of blood already in the arteries, which the ventricles must push against when they try to force new blood out during systole. Called ‘after’ because it is located after the ventricles in the path of blood flow.
Starling principle or Frank-Starling principle	When ventricle muscles are stretched by a larger preload, they are able to contract more strongly (unless they are stretched way too far)
Atrial natriuretic hormone/factor/peptide	A hormone secreted by the atria when they are stretched too far; it causes the body to release Na+ and water in the urine, decreasing blood volume and reducing the workload on the atria.
B-type natriuretic hormone/factor/peptide	Similar to ANH, but released from the ventricles when they are stretched.
Intrinsic regulation of heart function	The things that happen in the heart itself to regulate its function
Extrinsic regulation of heart function	The ways the rest of the body influences the heart, to keep it supplying the body with enough blood
Baroreceptors	Blood pressure-sensing cells in the carotids and the aorta
Baroreceptor reflex	The reflex in which the baroreceptors detect a change in blood pressure and the heart rate adjusts to bring it back to normal
Cardioregulatory center	The part of the medulla oblongata that controls heart rate
Precapillary sphincters	The rings of smooth muscle that can close off the blood from entering a capillary bed
Vasodilation	When the precapillary sphincters open. Lowers PR and BP
Vasoconstriction	When the precapillary sphincters close. Raises PR and BP
Local control of blood flow	When compounds that build up in a tissue or are formed by the lining of blood vessels cause the precapillary sphincters to open or close (what compounds would do this?)
NO	Nitric oxide – a vasodilating compound formed in blood vessels and tissues
Endothelin	A vasoconstricting compound formed in the lining of blood vessels

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