Cardiovascular Part One

bottom of heart

top of heart

mediastinum, lungs

double walled sac around heart: outer fibrous portion (protects/anchors/prevents overfilling), inner serous portion (parietal peritoneum/visceral peritoneum or epicardium)

filled w/ serous fluid to prevent friction

epicardium, myocardium, endocardium

often infiltrates w fat

autorrhythmic, compresses chambers

smooth to prevent clotting, folds make up valves

cardiac mm cells held together by ct fibers, arranged in spiral bundles to link parts of heart, reinforces myocardium, anchors cardiac mm, decreases stretch on vessels/valves, limits spread of APs to certain pathways

r: smooth posterior wall, ridged anterior wall (pectinate mm), l: mostly smooth, pectinate mm only in auricle

small appendages that increase atrial volume

trabeculae carnae (mm on internal walls), papillary mm (project into ventricles), chordae tendinae (anchor av valves to pap mm during contraction)

prevent blood backflow, respond to differences in bp

short low pressure circulation of deoxygenated blood to lungs

long pathway that encounters lots of resistance, oxygenated blood from lungs to body

receives blood from vena cava, moves blood to r ventricle thru tricuspid valve (coronary sinus: drains blood from myocardium)

receives blood from r atrium, pumps blood to lungs thru pulmonary semilunar valve/pulmonary artery

receives blood from lungs/pulmonary veins, moves blood to l ventricle thru bicuspid valve

receives blood from l atrium, pumps blood to body thru aortic semilunar valve/aorta

functional blood supply to myocardium, coronary vessels in epicardium send branches to myocardium, deliver blood when heart relaxed

alternate routes for blood, not strong enough to provide adequate blood supply if blocked

sequence of events in 1 beat

regulated by intrinsic conduction system, non-contractile, allows rapid ap conduction thru heart via gap jcts, unstable resting potential that continuously depolarizes (pacemaker potential)

sinoatrial node, atrioventricular node, bundle of His, Purkinje fibers

natural pacemaker, intrinsic rhythm ~100bpm, in r atrium near svc, impulse travels to av node causing atrial contraction

small mass of special mm in lower interatrial septum, slows impulse to allow for contraction of both atria, slower d/t smaller fibers/fewer gap jcts

speeds up impulse/transmits in to r/l bundle branches in upper interventricular septum, only bundle of his has gap jcts not atria/ventricles

extend to pap mm/ventricle walls, receives impulse from bundle branches/transmits it to ventricular myocardium causes almost simultaneous contraction

pacemaker activity shifts (ectopic pacemaker), slower firing of impulses