Ch 18 Flashcards
Pericardium
double walled sac enclosing the heart
Fibrous pericardium
dense connective tissue layer, protects heart, anchors to surrounding structures, prevents overfilling of heart
Serous Pericardium
Thin, slippery, 2 layer membrane forming closed sac around heart
Parietal layer of serous pericardium
lines internal surface of fibrous paricardium
Visceral layer of serous pericardium
Aka epicardium, covers external heart surface
Myocardium
Middle layer, mostly composed of cardiac muscle, forms bulk of heart
Endocardium
Lines heart chambers and covers fibrous skeleton of valves
Atria
Receive blood returning to heart.
Right atrium receives blood from sup. and inf. vena cava, and coronary sinus.
Left atrium receives blood from 4 pulmonary veins.
Ventricles
Thicker walls propel blood out
Atrioventricular (AV) valves
present backflow from V to A.
Tricuspid and bicuspid (mitral) valves
Chordinae tendinae anchor cusps to papillary muscles
Semilunar (SL) valves
As bases of large arteries from ventricles
Pressure causes open and close
Pulmonary SL valve
Aortic SL valve
Path of blood
Blood returns to heart via coronary sinus, sup. and inf. vena cava, into right atrium, thru tricuspid valve into right ventricle, out pulmonary SL valve into pulmonary trunk. Travels to lungs via pulmonary artieries, blood is reoxygenated, returns to heart by 4 pulmonary veins into left atrium. Thru bicuspid valve into left ventricle, out aortic SL valve into aortic arch, dist. to body tissues.
cardiac muscle
Short, fat, branched, interconnected cells. Impulses are transmitted across entire heart.
Heart contracts as a unit, refractory period is as long as contraction.
P wave
Atrial depolarization
QRS complex
Ventricular depolarization
