Heart chambers

Myocardium

-composed mainly of cardiac muscle and forms the bulk of the heart -layer of the heart that contracts

left atrium

-receives oxygen-rich blood form four pulmonary veins -acts as a holding chamber for blood returning from the lungs -walls are thicker on the left atrium due to the functionality

layers of the heart wall

1. Epicardium 2. Myocardium 3. Endocardium

right atrium

1. two distinguishing parts -smooth-walled posterior -rigid-walled anterior portion made of bundles of muscle tissue called pectinate muscles 2. crista terminalis separate the posterior and anterior regions of the right atrium 3. receives oxygen poor blood from the venous system

Two atria are superior to two ventricles. Which of these forms the most posterior surface of the heart?

Left atrium -The left atrium is the most posterior chamber. -The left ventricle composes part of the inferior surface. -The right atrium forms the right border. -The right ventricle is immediately behind the sternum and is, therefore, typically the most anterior surface of the heart.

Two atria are superior to two ventricles. Which of these contains the thickest wall?

Left ventricle The left ventricle is thicker than the right ventricle due to its need to withstand the force required to propel blood throughout the body. Atria are relatively thinner structures.

Two atria are superior to two ventricles. Which of these characteristically contains the crista terminalis?

Right atrium -The right atrium characteristically contains the crista terminalis. -The left atrium contains the interatrial band and the septoatrial bundle. -The right and left ventricles contain trabeculae.

Epicardium

layer that covers the external surface of the hear and is in contact with serous layer of the pericardium

Endocardium

lines the heart chambers and covers the fibrous skeleton of the valves

chambers of the heart

right atrium, right ventricle, left atrium, left ventricle

inferior ventricles of the heart

these two ventricles collect and expel blood toward the peripheral beds whiting the body and lungs.

superior atria of the heart

two upper chambers that receive blood from pulmonary and venous circulation and moves it to the heart ventricles