Circulatory System Facts and Information

As the name suggests, circulatory system is concerned with the circulation of fluids across various parts of the body. In fact, it is not merely the circulation of blood but the transportation of dietary substances and respiratory gases to and from the individual cells throughout the body.

Working in coordination with other human body systems, this vital system also plays its role in fighting diseases and maintaining homeostasis in the body. It consists of different organs of the body, including heart, blood and blood vessels as the major organs. Here heart is the pumping organ; blood is the circulatory fluid; and vessels serve as a pathway for the circulatory fluid to pass through.

A number of circulatory system facts are discussed here which you might not have heard of ever before. Some of these are listed as under. Just go through them to entertain yourself and increase the pool of your knowledge about human anatomy.

Circulatory System Facts
  • If all the small and large blood vessels are taken out from the body of an adult human and joined end-to-end in a straight line, they would stretch as long as 100,000 kilometers in length, i.e. enough to wrap around the planet earth two and a half times! Please not that the circumference of earth is around 40,000 kilometers or 25,000 miles.
  • The diameter of capillaries is extremely small, i.e. measuring just 1/3000th of an inch or 8 microns. Comparing it with the breadth of human hair, it is ten times smaller.
  • As the diameter of red blood cells is the same as that of capillaries, the former have to move in single-file lines to pass through these tiny vessels.
  • Some capillaries have got diameter even smaller than that of the red blood cells, so the latter have to distort their shape to pass through the narrow channels.
  • As for the resting heart rate is concerned, it increases as the body size of an animal in the animal kingdom decreases. That is why big bodies have slower rate of heat beat.
  • An adult human and sheep have got the same heart beat rate, i.e. their heart beats for 75 times in a minute while the body is in rest.
  • A shrew has got an amazingly high heart beat rate, which is 1,000 times/minute, while the heart of blue whale beats for only five times in a minute!
  • Here is another fact about circulatory system. Do you know the size of heart in blue whale? It is as large as a compact car!
  • As the heart is capable of generating its own electrical impulses, it will keep on beating even if taken out of the body provided that sufficient supply of oxygen is maintained.
  • The earliest discussion on the circulatory system appeared in an Egyptian medical document, called Ebers Papyrus, that dates back to the 16th century BC.
  • Egyptians, being cardiocentric, believed that it is not the brain but heart that is the source of wisdom, memories and emotions.
  • Giving little value to brain, during the process of mummification, the Egyptians extracted and discarded it while carefully preserving heart and other organs.
  • The ancient Egyptians described a physiological connection between the heart and the arteries, whereby explaining that after passing through the lungs, the air enters the heart and makes its way to the arteries.
  • The distinction between the functioning of the venous and arterial blood was first made by Galen of Pergamon, a Greek physician and philosopher.
  • The special thing about your red blood cells is that they are without nuclei. In this way, their capacity to carry oxygen gets increased.
  • Do you know due to the absence of nuclei, the RBCs (Red Blood Cells) are unable to divide or produce new cellular components?
  • The red blood cells are produced in the bone marrow and have average lifespan of four months, after which they die.
  • A sudden, temporary weakening of myocardium is known as cardiomyopathy which results in the symptoms similar to that of heart attack.
  • Do you know that the ‘broken heart syndrome’ or cardiomyopathy is caused by an emotionally stressful event of separation from a loved one?
  • Nowadays, a number of diagnostic tests on the heart are performed with the help of cardiac catheterization that involves the threading of a long, thin tube to the heart through the blood vessels.
  • The common medical procedure of cardiac catheterization was invented by Dr. Werner Frossman in 1929, who initially experimented it on himself.
  • Contrary to the common belief, the blood flowing in human body is not blue but either dark red or bright red. Indeed, the blue color of veins is because of the high energy blue light that penetrates the veins and is reflected back to reach the eyes.
  • The dark blue color of the oxygenated blood in arthropods and mollusks is because of the absence of hemoglobin and the presence of hemocyanin protein.
  • Due to the action of gravity on earth, the blood pooling occurs in legs, while in space blood pools in chest region.
  • The puffy faces, stuffy noses and headaches in astronauts are caused by the accumulation of more blood in the chest and head regions.
  • Living in space results in the decrease in overall volume of blood. It is because the body systems interpret the access of blood in head and chest as an abnormally increased quantity, so they tend to decrease it through different mechanisms.
  • The food particles, from digestive system, enter circulatory system and make their way to all the parts of body.
  • The waste products circulating in blood are discharged out of the body through excretory system.

The circulatory system facts make us realize that it works as a food supply chain in the body, delivering food particles to all the cells where the process of energy extraction takes place. While executing its essential functions, it comes with various other systems of the body, such as endocrine system, integumentary system, lymphatic system, muscular system, nervous system, respiratory system, skeletal system and reproductive system, etc.

About the Author

Posted by: M. Isaac / Senior writer

A graduate in biological sciences and a PhD scholar (NCBA&E University, Lahore), M. Isaac combines his vast experience with a keen and critical eye to create practical and inherently engaging content on the human body. His background as a researcher and instructor at a secondary school enables him to best understand the needs of the beginner level learners and the amateur readers and educate them about how their body works, and how they can adopt a healthier lifestyle.

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