Heart
around the heart
Pericardium
allowes heart to beat without friction, provides room to expand, yet resists excessive expansion
anchored to diaphragm inferiorly and sternum anteriorly
Fibrous Pericardium
outer wall, not attached to heart
Serous Pericardium
Parietal layer
lines fibrous pericardium
Visceral Layer (Epicardium)
covers heart surface
Pericardial cavity
space filled with pericardial fluid
Percarditis
painful inflammation of membranes, can put dangerous pressure on heart
Heart Wall
Endocardium
Adipose in thick layer in some places
Coronary blood vessels travel thru this layer
smooth inner lining of heart and blood vessels
covers valve surfaces and is continuous with endothelium of blood vessels
Myocardium
layer of cardiac muscle
spirals around heart producing wringing motion, vortex of heart
fibrous skeleton of the heart, framework of collagenous and elastic fibers
structural support and attachment for cardiac muscle and anchor for valve tissue
electrical insulation between atria and ventricles, important in timing and coordination of contractile activity
double-walled sac that encloses the heart
Coronary Circulation
5% of blood pumped by heart is pumped to the heart itself
click to edit
250 mL of blood per minute
needs abundant O2 and nutrients
features I am less familar with
4 Valves
between R/L atria and their R/L ventricle (respectively)
Atrioventricular valves
each ventricle and its great arteries
Tricuspid
Semilunar valves
Pulmonary Valve
opening between right ventricle into pulmonary trunk
Aortic Valve
opening between left ventricle into Aorta
Bicuspid
Chordanae Tendonae
Trabecula Carnae
Papillary Musles
2 main types of Heart Cells
1%
Pacemaker Cells
99%
Contractile Cells
Electrophysiology
Voltage
difference in electrical potential between 2 points
membrane potential
voltage difference across membranes of all cells
resting membrane potential
membrane potential of excitable cell at rest (not stimulated) averages between -60 and -90 mV
difference in concentration of ions across plasma membrane
electrical signature
Rapid Depolarization due to Na+ inflow
Plateau due to Ca2+ inflow when voltage gated slow Ca2+ channels open and K+ outflow when some K+ channels open
Repolarization from closure of Ca2+ channels and K+ outflow as more K+ channels open
allows for refilling of heart chambers
electrical signature
Pacemaker potential - slow depolarization is due to both opening of Na+ channels and closing of K+ channels
Depolarization - begins when pacemaker potential reaches threshold, then Ca2+ influx thru Ca2+ channels
Repolarization - Ca2+ channels inactivating, K+ channels opening allowing K+ efflux and return to most negative voltage
ECG
Electrocardiogram
Dysrhythmia or arrhythmia
disturbance in electrical rhythm)
Bradycardia
less than 60 bpm
Tachycardia
more than 100 bpm
atrial fibrilation
not as serious, p wave wonky
ventrical fibriliation
very serious, life-threatening, must treat with defibrilator