Circulatory system: what it is, parts and characteristics.

An overview of the parts, characteristics and biological functions of the circulatory system.

According to the latest estimates, an adult human being weighing 70 kilograms and standing 170 centimeters tall is composed of approximately 30 trillion cells.

Of these, a significant percentage comprises red Blood cells, since it is estimated that there are approximately 5 million of them per microliter of blood. If we take into account that a human being has about 5 liters of blood running through his ducts and bathing his organs, the number of total red blood cells skyrockets.

These data exemplify that the circulatory system is one of the most important at the physiological level for the human being. Our tissues are "living" entities to a certain extent, as they generate waste substances that need to be removed and nutrients to perform metabolic functions. Without a network of fluid tissues to take care of this task, the life of complex multicellular beings like us (beyond jellyfish) would be impossible.

Yes, you read that right: blood is a liquid connective tissue. This is just one of the many curiosities of the circulatory system, and we tell you all about them in the following lines.

Circulatory system: what is it and what are its parts?

From a physiological point of view, this apparatus is defined as the one that contains the heart (the organ of life par excellence) and the blood vessels, which allows it to move the blood through the body and all the organs and tissues that compose it.

This conglomeration of pipes and fluids allows the organs to receive oxygen and nutrients and at the same time to get rid of metabolic waste substances, potentially toxic if stored in excess.potentially toxic if stored in excess.

In most informative sources, the lymphatic system (through which lymph flows, redundancy notwithstanding) is considered part of the circulatory system. For informative purposes, we will leave this second system for another opportunity.

Beyond these data, it is necessary to name, even if only briefly, each of its parts in order to know the circulatory system as a whole. Let's get down to it.

1. The heart

The heart is defined as the central organ of blood circulationIn lower animals it is a simple dilatation of a vessel and in higher animals it is muscular, contractile, and has two, three or four chambers. You read that right, because not all organs of a cardiac nature are composed of two ventricles and two atria as in humans.

For example, amphibians have two atria and one ventricle, in which a mixture of partially oxygenated and deoxygenated blood is produced.

The heart is considered to be the strongest muscular structure in our body.It beats tirelessly more than 3,000 million times during our lifetime and pumps more than 7,000 liters of blood daily, an inconceivable figure from a human point of view. The liver accounts for 40-50% of this cardiac output.

2. Blood vessels

This includes veins, arteries and capillaries. We will quickly tell you what each of these structures of tubular and conductive nature consist of.:

• Capillary vessels: these are small branches of the blood network that reach the most hidden corners of the body, as no tissue is free of them.
• Arteries: the vessels that distribute the oxygenated blood coming from the lungs to the rest of the organs.
• Veins: the vessels that carry the deoxygenated blood back to the heart and lungs so that it can be oxygenated and thus repeat the cycle.

We are dealing with a blood tissue transport system that, if interrupted, can have serious consequences on the physiology of the individual.Have you ever heard of death by thrombosis? In these cases, a plug or thrombus (usually fat or clotted blood) is generated in an artery and, by the normal flow, is transported to an area of smaller diameter than the one from which it originated. When the thrombus cuts off the blood flow, the effects on the individual's physiology can be lethal.

3. Blood

How can we leave out the blood, the connective tissue that gives meaning to this whole system? Blood is famous for its oxygen transport (thanks to red blood cells, specifically hemoglobin, the hemoprotein that transports oxygen), but it also fulfills many other functions at an organic level.

For example, few people know that blood has a high concentration of circulating proteins (especially albumin, which accounts for up to 55% of the total), which help maintain plasma oncotic pressure and act as carriers of lipids and steroid hormones. Oncotic pressure, for example, is essential for the functioning of the organism, as it allows extracellular fluids to flow through the body.It allows extracellular fluids and blood volumes to be "in place". If an imbalance occurs, the famous and dreaded edemas appear, i.e., excessive accumulation of fluid under the skin or in certain body cavities.

The composition of the blood is distributed as followsBlood plasma (55%, acellular component) and formal components (the remaining 45%, composed of red blood cells, serum proteins and leukocytes of immune function, among many others).

Visit the functions of the bloodAmong the functions of the blood, we find the following as the most relevant:

• To participate in the defense against infections, by the transport of white blood cells to the affected site.
• To participate in the transport of nutrients and oxygen to all the cells of the body.
• Transporting waste substances from the tissues to the lungs (in the case of CO2) and the liver and kidneys.
• Participate in body thermoregulation.
• Transport hormones, enzymes, serum proteins and other substances of a regulatory nature as far as metabolism is concerned.
• Being essential for clotting and healing, among other things by transporting platelets to the affected site.

Curious facts about the cardiovascular system

This is a series of data that exemplify the importance and functionality of the circulatory system at the physiological level.. Among them, we find the following:

• From end to end, and comprising all veins, capillaries and arteries, the circulatory system would comprise about 100,000 kilometers.
• The heart pumps about 5 liters of blood per minute, that is, almost all of this fluid from the organism in only 60 seconds.
• The heart and kidneys expend about 500 kilocalories per day. Simply pumping and purifying blood accounts for ¼ of the total energy consumed each day.
• The heart beats about 80 times per minute, generating enough energy to move a vehicle from a theoretical point of view.

Among all this jumble of data, it is striking to discover that the vascular tissue of a human being, if put in a row, would be enough to make two laps around the world. the vascular tissue of a human being, if it were lined up in a row, would be enough to circle the Earth itself two and a half times.. Eighty percent of this value corresponds to blood capillaries, units in which veins and arteries branch out.

Diseases and considerations

Did you know that, in developed countries, the leading cause of death is ischemic heart disease, followed only by heart attacks? Obstruction of the coronary arteries and blood flow are, shocking as it may seem, the leading cause of death throughout the world. the entire globe.

For the circulatory system to function at full efficiency, it is essential to keep parameters such as cholesterol and body weight in check.

Overweight (present in more than 1.9 billion of the world's population) and obesity (650 million of this total) are proven risk factors for certain cardiovascular pathologies, such as coronary heart disease, heart failure, atrial fibrillation and the appearance of arrhythmias, among many others, not to mention other risks such as colorectal cancer or stomach ulcers.

In short: maintaining a healthy body means, in almost all cases, reducing the risk of death due to circulatory accidents..

Summary

We have made a brief tour of the circulatory system, since to cover each and every one of the structures included here would be enough for a whole saga of books. If we want you to keep one idea in mind, it is the following: the heart is the organ that works the hardest in living beings at a physiological level and, thanks to it, each and every organ and tissue is nourished and allows the excretion of potentially harmful substances.

Errors in the circulatory system are serious When the blood flow is cut off, isolated cells die quickly and irreversibly. Therefore, taking care of oneself on a physical and emotional level is always the best prevention to avoid a vascular accident.

Bibliographic references:

• Definition of circulatory system, NIH. Retrieved December 26 at https://www.cancer.gov/espanol/publicaciones/diccionario/def/sistema-circulatorio.
• The circulatory system, Connecticuts children. Retrieved Dec. 26 from https://www.connecticutchildrens.org/health-library/es/parents/heart-esp/.
• Circulatory system, Medlineplus.gov. Retrieved Dec. 26 from https://medlineplus.gov/spanish/ency/esp_imagepages/8747.htm.
• Circulatory system, visiblebody.com. Retrieved Dec. 26 from https://www.visiblebody.com/es/learn/circulatory.