Check out the Respiratory System series, https://www.youtube.com/watch?v=GfR7zxwjmFQ&t= Which chamber of the heart pumps blood into the pulmonary artery? a. the left atrium b. the right atrium c. the left ventricle d. the right ventricle Which chamber of the heart pumps blood into the systemic circulation? a. the left atrium b. the right atrium c. the left ventricle d. the right ventricle Which chamber of the heart receives blood from the pulmonary circulation? a. the left atrium b. the right atrium c. the left ventricle d. the right ventricle Which layer of the heart is composed of tough fibrous tissue? a. the endocardium b. the myocardium c. the epicardium d. the pericardium The endocardium is composed of a. tough fibrous tissue b. cardiac muscle c. smooth, squamous endothelial cells d. ciliated, cuboidal epithelial cells Which layer of the heart is composed of cardiac muscle? a. the endocardium b. the myocardium c. the epicardium d. the pericardium