LEFT ATRIUM • general features: lies to the left of and slightly posterior to the right atrium; receives blood from the pulmonary blood circuit via the pulmonary veins; • right and left pulmonary veins: total of _________________ vessels; drain into the left atrium; return oxygenated blood to the heart from the _______________; • auricle of the left atrium: similar in structure to the auricle of the right atrium; only part of left atrium to contain pectinate muscles; LEFT VENTRICLE • general features: walls are thickest in this chamber; receives blood from the left atrium; drained by the aorta; trabeculae carneae are muscle bundles that line the ventricular walls; • left atrioventricular valve: also known as the ___________________ or __________________ valve; consists of 2 cusps; made up of dense connective tissue covered by endothelium; • papillary muscles of the left ventricle: are ____________ in number; internal projections of the myocardium; each attaches to a separate cusp of the bicuspid valve via the chordae tendineae; • aorta: drains the left ventricle; carries blood to most parts of the body within the systemic blood circuit; • aortic semilunar valve: similar in structure to the pulmonary semilunar valve, consisting of 3 cusps; made up of dense connective tissue covered by endothelium.

Chambers of the heart RIGHT ATRIUM • general features: thin-walled chamber that lies superior to the right ventricle; receives blood from the systemic blood circuit; • orifice of the superior vena cava: located in the superior region of the right atrium; • orifice of the inferior vena cava: located in the inferior region of the right atrium; backflow of blood is prevented by the presence of the Eustachian valve; • auricle of the right atrium: ear-shaped pouch/extension of the right atrium; projects to the left from the root of the superior vena cava; • pectinate muscles: also called musculi pectinati; parallel muscular ridges on the internal wall of the majority of the right atrium and the right auricle; • interatrial septum: partition between the ___________________________ and the ________________________________; • fossa ovalis: shallow depression in the interatrial septum; remnant of the foetal _________________________________; • coronary sinus opening: located internally in the wall of the right atrium; lies between the orifice of the inferior vena cava and the right atrioventricular opening; receives all blood draining from the heart itself; protected by a semilunar fold of the endothelium of the heart called the coronary valve

From what structure/vessel do the left and right coronary arteries arise?Multiple choice question.pulmonary trunkleft atriumright atriumaorta

RIGHT VENTRICLE • general features: wall thickness is less than that of the left ventricle; receives blood from the right atrium via the right atrioventricular orifice; • trabeculae carneae: criss-crossing muscular ridges on the internal walls of the ventricle; composed of myocardium; • right atrioventricular valve: also known as the _______________________ valve; consists of three triangular-shaped flaps called cusps; consists of dense connective tissue covered by endothelium; • papillary muscles of the right ventricle: internal cone-shaped projections of the myocardium; each attaches to a separate cusp of the tricuspid valve via the chordae tendineae; • chordae tendineae of the right ventricle: fibrous cords that attach the cusps of the tricuspid valve to the papillary muscles; function to maintain closed state of right atrioventricular valve; • interventricular septum: thick muscular partition that separates the ___________________________ from the __________________________; • pulmonary trunk: carries all blood from the right ventricle into the pulmonary circuit where the blood receives oxygen from the lungs (become oxygenated); • pulmonary semilunar valve: found in the origin of the pulmonary trunk; consists of three cusps; made up of dense connective tissue covered by endothelium; functions to prevent backflow of blood.

What structure empties blood into the left ventricle?Multiple choice question.left atriumpulmonary veinsright ventricleaorta

Which of the following structures is found between the right atrium and the right ventricle in a mammal?Multiple choice question.The SA nodeThe aortic valveThe tricuspid valveThe bicuspid valve