As important at it is for circulatory system anatomy and physiology, your heart is only about the size of your closed fist. It consists of four chambers through which blood will flow in a defined pathway through your blood vessels. The two upper chambers are called atria. The lower and larger chambers are called ventricles. Blood flow is directed through your heart through a series of valves which will lead deoxygenated blood into your lungs.
Blood is received in your heart in its right atrium. From there it will flow into your right ventricle. Blood will leave your heart briefly through the pulmonary trunk which will branch into two blood vessels to direct blood flow to each of your lungs where it will receive oxygen.
Next, blood will return to your heart through your pulmonary veins to the left atrium. Blood then enters your left ventricle which will lead your heart through the aorta, found on the top of your heart. Then, it will be on its journey to provide your cells with oxygen and help remove waste products.
The primary purpose of your circulatory system is to deliver oxygenated blood and nutrients to your body, while removing wastes. It accomplishes this through a network of blood vessels. There are two major types of blood vessels. Veins carry deoxygenated blood to your heart. Arteries then deliver the oxygen-rich blood to your body. The blood vessels descend in size until they become capillaries, the smallest of blood vessels.
Not all parts of your body are fed directly by blood vessels. Ligaments, for example, attach bones to bones and are not highly vascularized. This is why ligament injuries can take a longer time to heal. Other parts of your body are filled with blood vessels such as your lungs and liver because of the role each of these organs play.
The naming of blood vessels gives you an indication of their size and position in the human body. Smaller arteries are called arterioles, while smaller veins are called venules. At rest, most of your blood will be located in your veins and venules. Capillaries connect arterioles and venules where exchange will occur between the cells of your body and its blood.
Another aspect of circulatory system anatomy is how blood vessels are named. The name will tell you where the blood vessel is found, oftentimes using the name of the bone it may lie above or using a medical term which describes the area of the body.
Blood vessels found on your forearm, for example, are called radial and ulnar, after the two bones that make up this part of your arm. The brachial region is your upper arm, with the principle blood vessels including this term in the name such as the brachial artery.
Your blood consists of liquid plasma, red blood cells, white blood cells, and platelets. Red blood cells carry oxygen to other cells in your body. White blood cells primary function is defense, whether it is an allergen that makes you sneeze or a disease-causing bacteria. Platelets promote clotting in case the closed system of your body is breached.
Your circulatory system anatomy is a complex system of two pumps, your atria and ventricles, and a network of blood vessels which move blood throughout your body. This small organ and its approximately 60,000 miles of blood vessels are a prime example of your body's efficiency.
Texas Heart Institute: Heart Information Center – texasheart.org
Tortora, Gerald J. and Reynolds Grabowski, Sandra. Principles of Anatomy and Physiology. 1996.