Chapter 19- Heart

carries blood to the lungs for gas exchange and returns it to the heart; supplied by right side of heart - pumps oxygen-poor blood to the lungs via the pulmonary trunk which divides into the left and right pulmonary arteries (deoxygenated blood)

– supplies blood to every organ of the body including other parts of the lungs and the wall of the heart; supplied by left side of heart - Pulmonary veins return oxygen-rich (oxygenated) blood to the heart; blood heart leaves via the aorta and returns via the inferior and superior vena cavae

systemic - oxygenated pulmonary - deoxygenated

systemic - deoxygenated pulmonary - oxygenated

Heart located in mediastinum, between lungs Base—wide, superior portion of heart, large vessels attach here Apex—tapered inferior end, tilts to the left

-double-walled sac that encloses the heart -Allows heart to beat without friction, provides room to expand, yet resists excessive expansion - Anchored to diaphragm inferiorly and sternum anteriorly

outer wall, not attached to heart

-Parietal layer—lines fibrous pericardium -Visceral layer (epicardium)—covering heart surface

space between parietal and visceral layers of serous pericardium, filled with 5 to 30 mL of pericardial fluid

painful inflammation of the membranes

epicardium, myocardium, and endocardium

• Serous membrane covering heart • Adipose in thick layer in some places • Coronary blood vessels travel through this layer

• Smooth inner lining of heart and blood vessels • Covers the valve surfaces and is continuous with endothelium of blood vessels

• Layer of cardiac muscle proportional to workload -Muscle spirals around heart which produces wringing motion, vortex of the heart • Fibrous skeleton of the heart: framework of collagenous and elastic fibers -Provides 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

-L and R atria -The atria are receiving chambers that receive blood returning to the heart.

– L and R ventricles -R ventricle wraps around the L ventricle in a C-shape, but both ventricles have the same volume. -The ventricles are the “pumps” that eject blood.

Regulate the openings between the atria an the ventricles

three cusps; tricuspid valve

two cusps; mitral valve

attach the valves to the papillary muscles on the floor of the ventricle and stop valves from flipping inside out or bulging into the atria when the ventricles contract

Regulate blood flow from the ventricles into the great arteries; both have three cusps aka. =Aortic valve, Pulmonary valve

controls opening from L ventricle to the aorta

controls opening from R ventricle to the pulmonary trunk

5% of blood pumped by heart is pumped to the heart itself through the coronary circulation to sustain its strenuous workload * 250 mL of blood per minute * Needs abundant O2 and nutrients