Chp 18: Cardiovascular system: the heart Flashcards
Heart location and orientation
Heart is enclosed within mediastinum of thoracic cavity, btwn 2nd rib and 5th intercostal space. FLanked by lungs, Rests on diaphragm, base directed toward R shoulder. Apex points to left hip.
Pericardium
stabilizes, protects, confines heart while still allowing free movement
Layers of heart wall
Epicardium: superficial; visceral layer of serous pericardium; smooth, slippery texture
Myocardium: middle layer, forms 95% of the heart
Endocardium: inner layer, lines heart chambers
Average mass adult heart
M: 300 g
F: 250 g
4 chambers
Atria: 2 upper receiving chambers
Ventricles: 2 lower discharging chambers
R vs L heart
R heart: 02 poor blood
L heart: 02 rich blood
Cardiac muscle
striated, short, branched, interconnected
Intercalated discs
Anchor cardiac cells together, allow passage of ions and synchronization of contraction
Heart microanatomy
Large # of mitochondria ensure continuous aerobic respiration
lack of 02 causes what?
myocardial infarction and heart attack
Vessels returning blood towards the heart
Superior and inferior venae cavae return O2 poor blood from body cells
Coronary sinus returns O2 poor blood from heart muscle (coronary veins)
R and L pulmonary veins return O2 rich blood from lungs
Vessels carrying blood away from heart include
Pulmonary trunk: carries deoxygenated blood from R ventricle to lungs
Ascending aorta carries oxygenated blood from L ventricle to body organs
Ventricular Diastole
Coronary vessels receive blood
Anastomoses
Connections between arteries supplying blood to same region, provide alternate routes
Coronary arteries
branches of aorta above aortic semilunar valve
