A Guide to Understanding the Physiology of Circulation

One of the most important physiology systems that defines the organism is the physiology of circulation. As the name suggests, physiology of circulation means the study of the continuous movement of blood throughout the body pumped by the heart. Circulation is organism makes sure that oxygen rich blood reaches tissues while oxygen poor blood is moved away from the tissues back in the lungs.

As the study of the physiology of circulation was made centuries ago in 1628 by William Harvey, people before that had a vague idea of the physiology of heart and circulation. It was assumed that the arteries carried certain kind of air or spirit to the organs. No one really considered the backflow. However, as scientific advancements were made, especially in the field of biology, in 1941 Cournand made use of venous cauterization which lead to the modern cardiovascular research.

It is safe to say that we have come a long way when it comes to understanding the human body and specially the human heart.  Let’s take a brief look at what we already know about the physiology of circulation.

Existing Information on the Physiology of Circulation

There are three key components that play an important role in circulation;


The capillaries not only form a direct connection between the arteries and the veins, but they also help in the exchange of gases, nutrients, and metabolic waste between the tissues and the blood. Through the process of diffusion, osmosis and filtration, substances move out of capillaries from one end and return from another.

Blood Flow

The blood flows through the vessels from the arteries to the capillaries and finally into the veins. Much like the other liquids, blood also flows from a region of high pressure to a region of low pressure. The larger the diameter of the capillary, the less is the blood pressure and resistance.

Pulse and Blood Pressure

Pulse is the rhythmic expansion of the artery caused when the blood is pushed out from the ventricles. In general terms, blood pressure refers to the arterial blood pressure or the pressure create in the aorta.

While we already have a comprehensive understanding  of the physiology of  circulation in the arteries and function of Ventricular systole . But we have no understanding how blood returns back to atrium in the venous system except but loose theories that periphersal muscle contraction and respiration aids the motion . A discovery made by Dr. Dinker Belle Rai in the field has proven to be very significant. Dr. B Rai discovered the mechanical function of the atrial chambers of the heart. He performed an experiment on a canine heart which lead to the discovery that it is the atrial diastole that creates a negative pressure thus bringing the blood back to the heart.

This significant discovery about the physiology of circulation was made after almost 500 years of William Harvey’s discovery about the Ventricular Systole. This new knowledge opens doors of tremendous research related to prosthetic hearts and treatments for heart failures. The continuous ground breaking discoveries like this one indicate that we have a long way to go.

Learn more about the physiology of heart and circulation from Dr. B Rai’s recent book called “Mechanical Function of the Atrial Diastole: A new Discovery”. Buy your copy now.