Anatomy and Function of the Heart

• The heart is a complex organ containing several parts, each with specific functions carried out intricately.
• The heart receives deoxygenated blood from the body, pumps it to the lungs for oxygenation, and then pumps oxygenated blood back out to the body.

Heart Components

• The human heart comprises chambers, valves, layers, and blood vessels working together.

Sections of the Heart

• The heart pumps blood containing oxygen through the body to the organs.
• The heart has four hollow chambers: two on top (atria) and two on the bottom (ventricles), with two on the right and two on the left.
• The top right chamber is the right atrium, which receives deoxygenated blood and its muscles relax as blood flows in.
• The right atrium contracts once full, sending blood to the right ventricle.
• The bottom right chamber is the right ventricle, which is larger than the atrium.
• The right ventricle contracts to send deoxygenated blood to the lungs for oxygenation.
• Blood re-enters the heart from the lungs into the top left chamber, the left atrium.
• The left atrium contracts once full to send blood to the chamber directly below it.
• The bottom left chamber is the left ventricle, the largest and thickest chamber.
• It's large size is necessary to pump blood out of the heart and through the body.

Heart Valves & Septum

• Valves are located at the exit of every chamber.
• The tricuspid valve has three cusps and is located at the exit of the right atrium and entrance to the right ventricle.
• The tricuspid valve opens and closes to allow or stop fluid flow.
• The pulmonary semilunar valve is shaped like a half-moon leading to the lungs.
• When the right ventricle is full, it contracts which forces the pulmonary semilunar valve open allowing blood to flow through.
• The bicuspid or mitral valve has two cusps and is located at the exit from the left atrium into the entrance of the left ventricle.
• The aortic semilunar valve connects to the aorta and is shaped like a half-moon. The aortic semilunar location of this valve exits the left ventricle and enters the aorta.
• The septum divides the heart into right and left sides, separating deoxygenated and oxygenated blood.
• Separating the blood ensures that it sends fully oxygenated blood to the body.

Layers of the Heart

• The heart is composed of three distinct layers: the epicardium, myocardium, and endocardium.
• The outermost layer is the epicardium, protecting the heart from damage.
• The epicardium has fluid on its surface to reduce friction during contractions and contains blood vessels that supply oxygen to the heart muscle.
• The middle layer is the myocardium, the muscular layer responsible for heart contractions.
• The myocardium is the thickest layer of the heart.
• The innermost layer is the endocardium, the thinnest layer resembling a membrane.
• The endocardium covers the inside surface of the chambers and valves, protecting the inside surface of the heart and providing a smooth surface for blood flow.

Arteries and Veins

• Arteries, veins, and capillaries exist in the body.
• Arteries and veins facilitate blood flow.
• The main blood vessels connected to the heart are the vena cava, pulmonary artery, pulmonary vein, and aorta.
• The vena cava is a large vein bringing deoxygenated blood to the right atrium.
• The vena cava is divided into superior (top) and inferior (bottom) sections.
• The pulmonary artery runs from the right ventricle to the lungs, carrying deoxygenated blood.
• The pulmonary semilunar valve is located at the pulmonary artery's entrance.
• The pulmonary vein is located between the lungs and left atrium, carrying oxygenated blood from the lungs to the left atrium.
• The aorta is the largest artery in the body, carrying oxygenated blood from the left ventricle to the body and the aortic semilunar valve is at its entrance.

Pathway of Blood Through the Heart

• Deoxygenated blood flows through the superior and inferior vena cava into the right atrium.
• Once full, the right atrium contracts, forcing the tricuspid valve open and allowing blood to flow into the right ventricle.
• After the right ventricle is full, the tricuspid valve closes, the right ventricle contracts, and the pulmonary semilunar valve opens, allowing blood to enter the pulmonary artery.
• Blood flows through the pulmonary artery to the lungs, picks up oxygen, and enters the pulmonary veins on its way to the left atrium.
• Once full, the left atrium contracts, forcing the bicuspid valve open, letting blood flow into the left ventricle.
• When the left ventricle is full, the bicuspid valve closes, and the left ventricle contracts, forcing the aortic semilunar valve open, letting blood flow into the aorta for transport to the body.