1. Heart Structure 13(b)

5. Overview of the Heart – The heart is composed of cardiac muscle tissue. – The heart is about the size of a human fist. – Throughout your life, the heart beats an estimated 2-3 billion times.

6. Structure of the Heart – The heart is composed of: – Four chambers – Four valves – Two nodes. – Chambers: Fill with blood. The right side is low-oxygen and the left side is high in oxygen. – Valves: Build pressure in the heart and prevent backflow from the chambers. – Nodes: The SA and AV nodes generate the electric impulse that causes heart contraction.

12. 1.Blood comes to the heart via the superior & inferior vena cavae. 1.Collects in the right atrium. 2.Passes through the tricuspid valve to the right ventricle. 3.Passes through the pulmonary valve to the pulmonary artery. 2.Blood exchanged oxygen and carbon dioxide in the lungs. 3.Blood returns to heart via the pulmonary veins. 1.Collects in the left atrium. 2.Passes through the mitral valve to the left ventricle. 3.Passes through the aortic valve to the aorta.