 | Term | Definition |
| |
afterload |
the work the heart does while ejecting blood; a function of the arterial blood pressure, as well as the diameter and thickness of the ventricles |
| |
artioventricular node |
region at base of right atrium near interventricular septum, containing specialized cardiac muscle cells through which electrical activity must pass to go from atria to ventricles |
| |
artiventricular valve |
valve between atrium and ventricle of heart; AV valve on right side of heart is the tricuspid valve, and that on left side is the mitral valve |
| |
automaticity |
capable of spontaneous, rhytmical self-excitation |
| |
biscuspid valve |
another term for the left atrioventricular valve, also called the mitral valve |
| |
bundle of His |
nervelike structure composed of modified heart cells that carries electrical impulses from the atrioventricular node down the interventricular septum |
| |
cardiac cycle |
one contraction-relaxation sequence of heart |
| |
cardiac output |
blood volume pumped by each ventricle per minute (not total output pumped by both ventricles) |
| |
chordae tendineae |
strong, fibrous cords, that connect papillary muscles to the edges of atrioventricular valves; they prevent backward flow of blood during ventricular systole |
| |
conducting system |
network of cardiac muscle fibers specialized to conduct electrical activity between different areas of heart |
| |
contractility |
force of heart contraction that is independent of sarcomere length |
| |
coronary artery |
vessel deliverign oxygenated blood to the muscular walls of the heart |
| |
coronary blood flow |
blood flow to heart muscle |
| |
cusp |
a flap or "leaflet" of a heart valve |
| |
diastole |
period of cardiac cycle when ventricles are relaxing |
| |
ECG Lead |
combination of a reference electrode (designated negative) and a recording electrode (designated positive) that are place on the surface of the body and provide a "view" of the elctrical activity of the heart |
| |
ejection fraction |
the ratio of stroke volume to end-diastolic volume; EF=SV/EDV |
| |
electrocardiogram |
recording at skin surface of the electrical surrents generated by cardiac muscle action potentials |
| |
end-dialostic volume |
amount of blood in ventricle just prior to systole |
| |
endothelium |
thin layer of cells that lines heart cavities and blood vessels |
| |
end systolic volume |
amount of blood remaining in ventricle after ejection |
| |
epicardium |
layer of connective tissue closely affixed to out surface of the heart |
| |
Frank-Starling mechanism |
the relationship between stroke volume and end-diastolic volume such that stroke volume increases as end-diastolic volume increases; also called Starling's law of the heart |
| |
F-type sodium channel |
the "funny" sodium-conducting channel mainly responsible for the inward flow of positive current in autorhythmic cardiac cells |
| |
heart rate |
number of heart contractions per minute |
| |
heart sounds |
noise that results from vibrations due to closure of atrioventricular valves( first heart sound) or pulmonary and aortic valves (second heart sound) |
| |
intercalated disk |
structure connecting adjacent cardiac myocytes, having components for tensile strength (desmosomes) and low-resistance electrical patheways (gap junctions) |
| |
interventricular septum |
the muscular wall separating the right and left ventricles of the heart |
| |
isovolmetric ventricular contraction |
early phase of systole when atrioventricular and aortic valves are closed and ventricular size remains constant |
| |
isovolumetric ventricular relazation |
early phase of diastole when atroventricular and aortic valves are closed and ventricular size remains constant |
| |
laminar flow |
when a fluid flows smoothly throught a tube in concentric layers, without any turbulence |
| |
L-type calcium channel |
voltage-gated channel permitting clacium entry into heart cells during the action potentail; L denotes the long-lasting open time that characterizes these channels |
| |
mitral valve |
valve between left atrium and left ventricle of heart |
| |
myocardium |
cardiac muscle which forms heart walls |
| |
P wave |
component of electrocardiogram reflecting atrial depolarization |
| |
pacemaker potential |
spontaneous gradual depolarization to threshould of some nerve and muscle cells' plasma membrane |
| |
papillary muscle |
muscular projections from interior of ventricular chambers that connect to atrioventricular valves and prevent backward flow of blood during ventricular contraction |
| |
pericardium |
connective-tissue sac surrounding heart |
| |
preload |
the amount of filling of ventricles just prior to contraction; the end-diastolic volume |
| |
pulmonary valve |
valve between right ventricle of heart and pulmonary trunk |
| |
Purkinje fiber |
specialized myocardial cell that constitutes part of conducting system of heart; conveys excitation from bundle branches to ventricular muscle |
| |
QRS complex |
component of electrocardiogram corresponding to ventricular depolarization |
| |
refractory period (of cardiac muscle) |
time during which excitable membrane will produce action potential, but only to a stimuls of greater strength that the usual threshould strength |
| |
sinoartial node |
region in right atrium of heart containing specialized cardiac muscle cells that depolarize spontanesouly faster than other cells in the conducting system; determines heart rate |
| |
stroke volume |
blood volume ejected by a ventricle during one heartbeat |
| |
systole |
period of ventricular contraction |
| |
T-type calcium channel |
channel that carries inward calcium current that briefly supposrt diastolic depolarization of cardiac pacemaker cells |
| |
T wave |
component of electrocardiogram corresponding to ventricular repolarization |
| |
tricuspid valve |
valve between right atrium and right ventricle of heart |
| |
venous return |
blood volume flowing to heart per unit time |
| |
ventricular filling |
phase of the cardiac pump clecy during which the ventricles are resting and blood enter through the atrioventricular valves |
| |
ventricular function curve |
relation of the increase in stroke voulme as end-diastolic volume increases, all other factors being equal |
| Add or remove terms from this set |
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