Historical Perspective

Although the vital nature of the cardiovascular system was clearly apparent to the ancients, its actual function was a mystery. An early attempt to explain the function of the heart and the blood was made by the Greek physician and writer Galen (130-201 A.D.). He taught that there was an ebb and flow of fluid between the heart and the abdominal viscera, where the "natural spirits'' were formed; between the heart and the brain, where the "animal spirit'' was created; and between the heart and the lungs, where "vital spirits'' entered the body through the trachea. This erroneous concept remained a major cornerstone of medical thought for the next 14 centuries.

In 1628, William Harvey, an English physician and anatomist, published an article in which he proposed from "demonstrations and logical arguments'' that blood flows in a completely closed circulation. Even though Harvey could not actually see the microcirculation, he proposed its existence to complete the circuit from arteries to veins. Harvey's application of the scientific method finally gave rise to a modern era of understanding and investigation of cardiovascular physiology. Although Harvey appreciated the fact that the heart functioned as two pulsatile pumps connected in series to move blood around the system, it would still be another 200 years before the French physiologist Claude Bernard proposed that complex, multicellular organisms live in both an external and an internal environment. In the 1850s, he introduced the concept of the milieu intérieur to describe the fact that there is an internal fluid environment that surrounds and bathes all tissues of the body. The circulating blood, via a complex network of microscopic capillaries, provides for the exchange of ions, nutrients, wastes, heat, and chemical messengers with every cell in the body. He further recognized that the temperature and ionic and chemical composition of the internal environment are maintained remarkably constant even though the external environment that we live in is subjected to major fluctuations.

The constant state of this internal environment is maintained by intricate control systems with many sensors and effectors. In 1939, the American physiologist W.B. Cannon introduced the term homeostasis to refer to this maintenance of a state of uniformity in the fluid matrix of the body by the integrated activity of various physiological controllers. Many of these control systems work directly through the cardiovascular system and are explained in detail in subsequent chapters.

Get Rid of Gallstones Naturally

Get Rid of Gallstones Naturally

One of the main home remedies that you need to follow to prevent gallstones is a healthy lifestyle. You need to maintain a healthy body weight to prevent gallstones. The following are the best home remedies that will help you to treat and prevent gallstones.

Get My Free Ebook


Post a comment