The Cardiovascular System

labeled human cardiovascular system
Generally, blue means deoxygenated blood moving toward the heart and red means oxygen-rich blood moving away from the heart.

Combined with the lymphatic system, the cardiovascular system makes up the human circulatory system. This post focuses on the cardiovascular system.

While the cardiovascular system in some animals is open, the human system is closed, meaning the blood remains within the network of blood vessels. Oxygen and nutrients that are transported throughout the body via those vessels are able to cross the vessel layers and enter interstitial fluid and, eventually, to certain cells.

Waste and carbon dioxide are then carried through the same system in the opposite direction, away from the target cells and eventually out of the body.

The main organ of the cardiovascular system is, of course, the heart. The heart has four chambers: left and right atria and left and right ventricles. The organ has two main functions: pump deoxygenated blood to the lungs and pump oxygenated blood throughout the rest of the body.

The power to do all of this work comes from the myocardium, or heart muscle. Valves are in place to keep the blood flowing in one direction – the right direction.

The circulatory system is broken into three divisions.

labeled parts of the human heart1. The coronary circulatory system is how the blood circulates within the heart. Two coronary arteries branch into the aorta, the heart’s main artery that pumps blood throughout the body via three vessels. After oxygen and nutrients are depleted from the body, the blood is returned to the heart through the pulmonary veins – superior vena cava from the top and the inferior vena cava from the bottom.

2. The pulmonary circulatory system pumps deoxygenated blood away from the heart and to the lungs where it can be resupplied with oxygen. In the lungs, carbon dioxide is released from the blood and oxygen is absorbed. This is called gas exchange. Once the blood is oxygen-rich, it is returned to heart to be pumped throughout the body.

3. The systemic circulation system is how the blood is circulated to every inch of the body, except for the lungs. Human cells need oxygen and nutrients and they get them from systemic circulatory system.

Blood consists of plasma, red blood cells, white blood cells, and platelets.