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base of heart

posterior surface

Pericardium- fibrous pericardium

tough, inelastic, dense irregular connective tissue
prevents overstretching, protection, anchorage

Pericardium-serous pericardium

thinner, more delicate membrane-double layer (parietal layer fusted to fibrous pericardium, visceral layer also called epicardium)

epicardium

outer (external) layer
visceral layer of serous pericardium
smooth, slippery texture to outermost surface

myocardium

95% of heart is cardiac muscle

endocardium

inner layer-smooth lining for chambers of heart, valves and continuous with lining of large blood vessels

2 atria chambers

receiving chambers
auricles increase capacity

2 ventricle chambers

pumping..larger and muscular

sulci grooves

contain coronary blood vessels
coronary sulcus
anterior interventricular sulcus
posterior interventricular sulcus
sulcus surrounds the chambers

artrioventricular valves

tricuspid (between right atrium and ventricle) and bicuspid (between left artrium and ventricle)

right ventricle

pumps (deoxygentated) blood to lungs
shorter distance, lower pressure, less resistance

left ventricle

pumps (oxygenated) blood to body
longer distance, higher pressure, more resistance
works harder to maintain same rate of blood flow as right ventricle

semilunar valves

aortic and pulmonary valves
opens when pressure in ventricle exceeds pressure in arteries
as ventricles relax, some backflow permitted, blood fills valve cusps closing them tightly

systemic circuit

left side of heart...receives blood from lungs.. ejects blood into aorta..systemic arteries, arterioles..gas and nutrient exchange in systemic capillaries..sytemic venules and veins lead back to right atrium

pulmonary circuit

right side of heart...receives blood from systemic circulation...ejects blood into pulmonary trunk then pulmonary arteries...gas exchange in pulmonary capillaries...pulmonary veins takes blood to left atrium

coronary circulation

myocardium...own network of blood vessels, coronary ateries branch from ascending aorta-anastomoses provide alternate routes
allows heart muscle to receive sufficient oxygen even if artery is partially blocked
coronary capillaries, coronary veins-collect in coronary sinus and empires into right atrium

depolarization

contractile fibers have stable resting membrane potential

plateau

period of maintained depolarization..time for atria to contract

repolarization

recovery of resting membrane potential

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