5.1 Heart Layers, Valves, and Chambers

Endocardium layer

Innermost, squamous epithelium, lines chambers and valves, smooth surface that reduces friction as blood flows

myocardium layer

middle, thickest, cardiac muscle, heart pumping actions, left ventricle thickest as generates high pressure to pump blood

epicardium layer

outer, connective tissue, visceral layer of pericardium (serous)

Pericardium layer

protective fluid filled sac surrounding heart, two layers (1. fibrous - prevents heart expanding too much, tough, outermost, 2. serous - inner, produces pericardial fluid that lubricates heart as it beats)

Right atrium chamber

receives deoxygenated blood from superior vena cava, inferior vena cava, and coronary sinus. Thin-walled

right ventricle chamber

receives blood from right atrium, pumps deoxygenated blood to lungs through pulmonary trunk and arteries, wall is thicker than atria but thinner than left ventricle

left atrium chamber

receives oxygenated blood from lungs through four pulmonary veins, acts as reservoir before blood enters left ventricle

left ventricle chamber

receives blood from left atrium, pumps oxygenated blood into aorta and systemic circulation, has thickest myocaridum

tricuspid valve (atrioventricular)

separates right atria and right ventricle

bicuspid/mitral valve (atrioventricular)

separates left atria and ventricle

pulmonary valve (semi-lunar)

separates left ventricle and pulmonary trunk

aortic valve (semi-lunar)

separates left ventricle and aorta