Pathways of the Heart: A Visual Guide

The heart is a complex organ with four main chambers and several important structures.The upper chambers, called atria, receive blood returning to the heart.Below the atria are the ventricles, which pump blood out of the heart.The septum is a thick muscular wall that separates the right and left sides of the heart.The left ventricle has particularly thick muscular walls, as shown by these layers, because it needs to pump blood to the entire body.The tricuspid valve, with its three leaflets, controls blood flow between the right atrium and right ventricle.The mitral valve, also called the bicuspid valve because it has two leaflets, controls flow between the left atrium and left ventricle.The left ventricle's wall is approximately three times thicker than the right ventricle, allowing it to generate the high pressure needed for systemic circulation.Deoxygenated blood returns to the heart through two major veins.The superior vena cava brings blood from the upper body, while the inferior vena cava returns blood from the lower body.Blood flows from the right atrium through the tricuspid valve into the right ventricle.The right ventricle contracts, pushing blood through the pulmonary valve into the pulmonary arteries.The blood travels to the lungs where it picks up oxygen.In the lungs, the blood releases carbon dioxide and picks up oxygen through tiny air sacs called alveoli.The now oxygen-rich blood returns to the heart through the pulmonary veins, completing the pulmonary circuit.Now let's follow oxygen-rich blood through the systemic circulation.Oxygenated blood from the lungs enters the left atrium.The mitral valve opens, allowing blood to flow into the left ventricle.The powerful left ventricle contracts, forcing blood through the aortic valve into the aorta.Blood travels through the aorta and into a complex network of arteries.In the capillaries, oxygen and nutrients are delivered to body tissues.Now deoxygenated, blood returns through veins back to the right atrium.This completes our journey through the systemic circulation, where oxygen-rich blood is delivered to the entire body and returns deoxygenated to begin the cycle again.Thanks for learning about the circulatory system with Spark.E!