Layman’s Guide to the Circulatory System: Understanding the Structures, Functions, Complications and Diagnostic Tools

The principle organ in this complex network is the heart, but other parts of the human circulatory system include arteries, capillaries, blood, veins and venules.

Importance of those Beats per Minute

The human heart is a powerful muscular pump that contracts to send blood shooting out to the rest of the body through a network of arteries and blood vessels. It is composed of four chambers: two ventricles and two atria. Oxygen poor blood that has already circulated through the body returns to the heart via a major vein known as the vena cava. It collects in the right atria and right ventricle and is then pumped to the lungs through the pulmonary arteries. Here the blood is replenished with a fresh supply of oxygen before entering the left side of the heart to be pumped out to the body through the aorta.

The Anatomy and Functions of the Blood

This specialized body fluid is constantly flowing through the body and is made up of a number of components including red and white blood cells, eosinophils, plasma, platelets and clotting factors. Every cell in the body receives nourishment from oxygen rich blood, small wonder then that it is sometimes called the 'River of Life'. Its other principle function is to transport waste away from cells and tissues. In the average healthy adult there are approximately five liters of blood – that is about one eleventh of a person's body weight.

Plasma is the yellowish fluid that is the major constituent of blood (about 55%) and in it are suspended the millions of cells that make up the rest of its volume. These include red blood cells, or erythrocytes, white blood cells, or leukocytes, and platelets or thrombocytes. The platelets help blood to clot at the site of injury and without them a person would bleed to death. Other substances that are suspended within the blood plasma are salts, glucose and other nutrients.

Complications with the Circulatory System

If any structure within the circulatory system fails to function correctly serious and potentially life-threatening complications can occur. Diseases, defects and underlying health complications can cause problems with the valves, blood, vessels and the heart itself.

Diagnosing Circulatory Complications

There are many simple and noninvasive diagnostic procedures that are used to identify complications with parts of the circulatory system. For example, an echocardiogram and ultrasound can detect problems with the valves of the heart, while an ankle-brachial index and a duplex arterial scan detect vein and artery complications.

Diagnostic Blood Tests

Blood tests are simple and relatively painless, and say a lot about a person’s health. There are numerous types of blood tests which are used to help detect specific diseases, evaluate how well organs are functioning and check that medicines being taken are working.

Blood tests can detect whether or not red and white blood cells levels fall within normal range, as well as platelet levels. Variations in blood count levels are often an indication of a disease or condition that requires treatment. Blood tests reveal if high or low cholesterol is present, as well as cancers and other illnesses.


"Anatomy of the Human Circulatory System"

"Cardiovascular System"