Blood Flow through the Heart – Pathophysiology
Blood Flow Through the Heart
The heart is the muscular organ that pumps blood through the circulatory system and the rest of the body. It is vital for carrying oxygenated (i.e. oxygen-rich) blood from the lungs to the different tissues of the body, as well as for taking the waste products and deoxygenated (i.e. oxygen-poor) blood away from the tissues. This article will discuss the normal blood flow through the heart and will provide descriptions for each part of the circulatory system that is involved in this pathway.
Types of Blood Vessels
Learning the normal blood flow pathway of the circulatory system starts with having a basic understanding of the three main types of blood vessels. These include:
- Arteries. These blood vessels carry oxygenated blood away from the heart and towards all the tissues of the body. Because of their role, arteries contain higher pressure levels compared to veins. This is why the arterial blood flow is one directional and do not have valves. The easiest way to remember their function is: A in “arteries” means “away” from the heart.
- Veins. These blood vessels bring deoxygenated blood and waste products from the body’s tissues and back to the heart. Veins contain valves which keep the venous blood flow in one direction.
- Capillaries. These small and thin blood vessels are known as “bridges” between arteries and veins. Capillaries have thin walls that are required to exchange the oxygen and nutrients to sustain the cells, as well as waste products and carbon dioxide that cells excrete.
Blood Flow Pathway
Below is the summary of the blood flow pathway through the heart:
Body –> Inferior/Superior Vena Cava –> Right Atrium –> Tricuspid Valve –> Right Ventricle
–> Pulmonic Valve -> Pulmonary Arteries –> Lungs –> Pulmonary Veins –> Left Atrium
–> Mitral or Bicuspid Valve –> Left ventricle –> Aortic valve -> Aorta –> Body
Let us discuss the blood flow pathway in detail.
The Right Side of the Heart
- Vena Cava. Vena cava, which literally means “hollow vein”, is the largest vein in the body and serves as the entry port of the deoxygenated blood from the body tissues to the heart. The two vena cava are the superior vena cava, which brings blood from the brain, arms and other parts of the upper body, and the inferior vena cava, which carries the blood from the abdomen, legs, and other parts of the lower body. These two large veins deliver the blood to the right atrium.
- Right Atrium. The heart is divided into four chambers. The top two chambers are called atria, while the bottom two chambers are known as the ventricles. The right atrium pumps the deoxygenated blood from the vena cavas to the right ventricle, via the tricuspid valve.
- Tricuspid valve. One of the four heart valves, the tricuspid valve allows the blood to flow from the right atrium to the right ventricle. Once it has brought the blood to the right ventricle, it shuts to prevent the blood to back up the right atrium. The tricuspid valve is one of the two “atrioventricular” (AV) valves, which are valves that connect an atrium and a ventricle.
- Right Ventricle. This chamber of the heart pumps the deoxygenated blood to the pulmonary artery via the pulmonic valve.
- Pulmonic valve. One of the semilunar valves, this half-moon shaped valve prevents the blood to flow back up to the right ventricle once the blood has been delivered to the pulmonary arteries.
- Pulmonary Arteries. These arteries deliver deoxygenated blood from the right ventricle to the lungs. In the lungs, the process of blood oxygenation occurs.
- Pulmonary Veins. The pulmonary veins bring the oxygenated blood from the lungs to the left atrium of the heart.
The Left Side of the Heart
- Left atrium. From the lungs, oxygenated blood enters the left atrium. Then, the left atrium pumps the blood to the left ventricle via the mitral valve.
- Mitral valve. Also known as bicuspid valve, the mitral valve is another AV valve that functions as a link between the left atrium and the left ventricle.
- Left ventricle. The left ventricle pumps the oxygenated blood to the aorta via the aortic valve.
- Aortic valve. Another semilunar valve, the aortic valve prevents the blood to back up the left ventricle.
- Aorta. Aorta is known as the largest artery of the body. It pumps the oxygenated blood to the rest of the body through the systemic circulation. The aorta has thick, elastic walls in order to maintain blood pressure.