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cardiovascular system
consists of the heart and blood vessels, whose function is to circulate blood around the body, contributing to homeostasis
right and left atrioventricular (AV) valves
separated the atrium and ventricle on the respective sides, preventing backflow of blood from the ventricles into the atria during ventricular emptying
tricuspid valve
the right AV valves consisting of 3 cusps (flaps)
bicuspid or mitral valve
the left AV valve consisting of 2 cusps
chordae tendineae
the edges of the AV valve cusps are attached by thin chords of tendon-like tissue to small papillary muscles arising from the inner ventricular walls
aortic and pulmonary valves (also called semilunar valves)
located where the major arteries (pulmonary trunk and aorta) leave the ventricles and prevent backflow of blood into the heart
endocardium
thin inner layer of endothelium, a type of epithelial tissue which lines all of the circulatory system
myocardium
cardiac muscle; makes up most of the heart wall
epicardium
thin external membrane covering the heart
pericardial sac
double-walled and encloses the heart
pericardial fluid
provides lubrication as the heart moves
right and left coronary arteries
supplies heart with arterial blood and arise as branches of the ascending aorta
coronary sinus
large vein that collects deoxygenated blood at the back of the heart, which empties into the right atrium
autorhythmicity
action potentials generated by the heart itself
conduction system
specialized muscle fibers which do not contract but are specialized for initiating and conducting action potentials
sinoatrial node (SA node)
serves as the normal pacemaker of the heart
atrial systole
atria contract as a single unit
ventricular systole
depolarization and contraction of the ventricles
systole
phase of contraction (ventricles contract)
diastole
phase of relaxation (ventricles relax)
cardiac cycle
a complete heartbeat that consists of atrial systole and ventricular diastole occurring simultaneously, followed by ventricular systole and atrial diastole occurring simultaneously
relaxation period
last 0.4 seconds of the cardiac cycle where all chambers are in diastole
plateau phase of action potential
the membrane potential reversal to +30 mV as a result of opening of Na+ channels is maintained at this value for several hundred milliseconds
"slow" calcium channels
activation of these cause the plateau phase to occur
Electrocardiogram (EKG or ECG)
the recording of the electrical changes that accompany the heartbeat
P wave
small upward wave indicating atrial depolarization
QRS complex
slight downward deflection followed by a large upright triangular wave, representing ventricular depolarization
T wave
ventricular repolarization (atrial repolarization is obscured by the QRS complex)
stroke volume (SV)
the amount of blood ejected by a ventricle during each contraction
