rapid depolarization of the cell (i.e., the cell membrane potential increasing or becoming more positive as compared to its surroundings) followed by repolarization (i.e., the cell membrane potential decreasing back to the resting voltage)
afterload
the amount of systemic pressure that the heart must overcome to eject blood during systole
arteries
blood vessels that carry oxygenated blood away from the heart and to the tissues for perfusion; singular, artery
atria
the two upper chambers of the heart; singular, atrium
automaticity
a process by which a spontaneous action potential forms, allowing a tissue to act as the pacemaker of the heart
bundle of His
part of the electrical system of the heart
capillaries
small blood vessels that run between arteries and veins and allow oxygen perfusion and nutrient exchange; singular, capillary
cardiac output
the amount of blood pumped from the left ventricle per unit of time
contractility
the strength of the force of left ventricular contraction
depolarization
a process by which a cell’s negative baseline resting membrane potential increases and becomes positive
diastole
the phase of the cardiac cycle in which a chamber is relaxing or filling
dysrhythmias
irregularities in the heart rate or rhythm; singular, dysrhythmia
electrocardiography (EKG, ECG)
a common diagnostic tool that allows health care professionals to monitor various aspects of a client’s heart including rate, rhythm, or the presence of ischemia.
membrane potential
the voltage (i.e., ionic charge) of a cell as compared to its surroundings
preload
the volume of blood that fills the left ventricle at the end of diastole
pulmonary arteries
the blood vessels that carry deoxygenated blood from the right ventricle to the lungs for gas exchange; singular, artery
pulmonary veins
blood vessels that carry oxygenated blood from the lungs back to the left atrium of the heart; singular, vein
Purkinje fibers
special muscle cells that allow coordinated contraction of the heart
systemic vascular resistance
the resistance to blood flow within the artery, determined by the arterial diameter
systole
the phase of the cardiac cycle in which a chamber is contracting or pumping
veins
blood vessels that carry deoxygenated blood back to the heart
ventricle
one of the two lower chambers of the heart
waveforms
the upward and downward deflection on an electrocardiogram