1. Four chambers of the heart
Description:
RIGHT ATRIUM
▪ Forms the right border of the heart and receives blood from three veins:
➢ the superior vena cava
➢ inferior vena cava
➢ coronary sinus
▪ Is about 2–3 mm (0.08–0.12 in.) in average thickness
▪ It is also called the right atrioventricular valve.
LEFT ATRIUM
▪ Is about the same thickness as the right atrium and forms most of the base
of the heart. It is also called the left atrioventricular valve.
RIGHT VENTRICLE
▪ Is about 4–5 mm (0.16–0.2 in.) in average thickness and forms most of the anterior
surface of the heart
LEFT VENTRICLE
▪ Is the thickest chamber of the heart, averaging 10–15 mm (0.4–0.6 in.) and forms the
apex of the heart

Function:
RIGHT ATRIUM
▪ The right atrium receives blood low in oxygen from the body and then empties the blood into the right ventricle.
LEFT ATRIUM
▪ The left atrium receives blood full of oxygen from the lungs and then empties the blood into the left ventricle.
RIGHT VENTRICLE
▪ The right ventricle passes the blood on to the pulmonary artery, which sends it to the lungs to pick up oxygen.
LEFT VENTRICLE
▪ The left ventricle connects nearly all organ systems through its function to pump oxygenated blood to the body.

2. Structure of three layers of the heart
Description:
EPICARDIUM- outermost layer of the heart; the visceral layer of serious pericardium; comprised of mesothelial cells and fat and connective tissues.
MYOCARDIUM- muscle layer/ cardiac muscle tissue that forms the heart; comprised of cardiomyocytes
ENDOCARDIUM-thin layer of endothelium overlying a thin layer of connective tissue’ innermost layer of heart

Function:
EPICARDIUM- protects the heart; produces factor that help the cardiac cells properly develop; ensures proper response to the cardiac cell injury
MYOCARDIUM- responsible for keeping the heart pumping blood around the body
ENDOCARDIUM- keeps the blood flowing through the heart separate from the myocardium; lines the valves, which opens and close to regulate blood flow through the chambers of heart