main function: transportation, bloods is the means of transportation, it carries O2, digested foods, cell wastes, electrolytes, and many substances vital to the body's homeostasis to and from the body cells. it's propulsive force is the contracting heart.
cone-shaped organ approximately the size of a fist, located in the mediastinum (thorax).
the apical pulse may be heard in the 5th intercoastal space at the Point of Maximal Intensity
the double-walled fibroserous sac around the heart, the thin epicardium, or visceral pericardium is closelyt applied to the heart muscle.
the outer, loosely applied layer,
produced by heart layer membranes allow the heart to beat with little friction
lines the loosely fitting superficial fibrous pericardium composed of dense connective tissue.
(2 superior chambers) lined by serous endothelium called endocardium, function: receive blood and are ineffective as pumps. blood goes into atria under low pressure from the veins of the body.
Right side: receives oxygen-poor blood via the superior & inferior venae cavae and coronary sinus
Left side: four pulmonary veins deliver oxygen-rich blood from the lungs
(2 inferior chambers) lined by thin serous endothelium called endocardium, bulk of the heart, discharging chambers, force blood out of the heart into the large arteries,
Right: pumps blood into the pulmonary trunk, routes blood to the lungs to be oxygenated.
left: discharges blood into the aorta, which all systemic arteries of the body diverge to supply the body tissues.
Interatrial or Interventricular Septum
divides the hear longitudinally (depending on which chamber it partitions)
discussion of the heart's pumping action
Atrioventricular (AV) valves
enforce a one-way blood flow through heart chambers, located between the artial and ventricular chambers, prevents backflow into the atria when ventricles are contracting.
Mitral or bicuspid valve (left AV)
consists of 2 cusps or flaps of endocardium
Tricuspid valve (right AV)
has 3 cusps
tiny white collagenic cords (heart strings), anchor the cusps to the ventricular walls. originate from papillary muscles
small bundles of cardiac muscles, project from the myocardial wall
when blood is flowing passively into the atria and then into the ventricles (ventricle filling), the AV valve flaps hang limply into the ventricular chambers then are carried passively toward the atria by the accumulating blood.
when ventricles contract and compress the blood in their chambers, the intraventricular blood pressure rises, causing the valve flaps to be reflected superiorly, which closes the AV valves.
Pulmonary & Aortic (seminlunar, SL) valves
second set of valves, each composed of 3 pocketlike cusps, guards the bases of the 2 larger arteries leaving the ventricular chambers. the valve cusps are forced open and flatten against the wall of the atery as the ventricles discharge their blood, closing the semilunar vlaves and preventing arterial blood from reentering the heart.
Pulmonary Circulation pump
the right side of the heart, shunting the carbon dioxide-rich blood entering its chambers to the lungs to unload carbon dioxide and pic up O2, then back to the left side. function: gas exchange
carries O2 rich blood from the left heart through the body tissues and back to the right side of the heart, function: blood supply to all body tissues
blood supply of the heart
right and left arteries
issue from the base of the aorta just above the aortic semilunar valve and encircle the hear in the coronary sulcus at the junction of the artia and ventricles. the cover the hearts surface, the right: supplys the posterior surface of the ventricles and the lateral aspect of the right side of the heart largely into the interventricular and right marginal artery branches. the left: supplies the anterior ventricular walls and the laterodorsal part of the left side of the heart via its 2 major branches, the anterior interventricular artery, and the circumflex artery.
these arteries are compressed during systole adn fill when heart is relaxed.
is largely drained by the great, middle, ad small cardiac veins, which empty into the coronary sinus
in turn, empties into the right atrium. in addition, several anterior cardiac veins empty directly into the right atrium
major systemic artery; arises from the left ventricle of the heart, carries oxygen rich blood
carries oxygen poor blood, below aorta
Superior Vena Cava
carries oxygen poor blood, to the right the aorta, vein that returns blood from body regions superior to the diaphragm
Apex of the Heart
bottom tip of the heart
the medial cavity of the thorax containing the heart, great vessels, and trachea
layer of heart wall composed of cardiac muscle
pacemaker of the heart, sinus rhythm ~75 bpm
junctional rhythm ~ 40-60 bpm
Bundle of His
atrioventricular bundle, in interventricular septum, specialized fibers that conduct impulses from the AV node to the right and left ventricles