The 12 systems of the human body (and how they work).

An overview of the systems of the human body, and their organs and functions.

Since time immemorial, human beings have tried to understand the mysteries behind the functioning of their own body and what mechanisms are involved.

There is no shortage of organs that constitute us, which interact with each other to carry out their functions and keep us alive.

In this article we are going to approach the systems of the human bodyTheir functions, their characteristics and which are the main organs that constitute them.

What are the systems of the human body?

The smallest unit that forms an organism is the cell. This structure is grouped together with other cells forming the tissues that, in turn, form the organs. These organs interact with each other, carrying out functions together and forming the systems and apparatuses of the human body.

In order to coordinate efficiently and carry out their functions, the organs receive nerve impulses from the brain and spinal cord, as well as hormones that initiate different biological processes.

Medicine has been in charge of the study of the organs and their constituent systems, specializing in different branches of medicine.specializing in different branches that deal with them in greater depth. To give some examples, we have cardiology, ophthalmology, hepatology, among many others.

A first classification

Before going into more detail about the different types of systems, it is worth explaining a little about how they are classified. Although all systems are essential to keep the organism alive, they have a certain degree of hierarchy depending on the type of system.The systems are classified according to the role they play.

Group I: Somatic systems

These are the systems that shape the human body, protect it and perform biomechanical functions..

Group II: Visceral systems

They perform the vegetative functions such as, for example, metabolism, reproduction, digestion...

Group III: Circulatory system

They are responsible for the transport of fluids such as Blood and lymph.

Group IV: Nervous system

Regulates nerve impulses.

Human body systems: functions and characteristics

Let's see now what are the systems of the human body and their characteristics.

1. Nervous system

It is responsible for sending nerve impulses throughout the body, which allows functions such as voluntary control of movement, conscious decision making, thinking, memory and other cognitive aspects.

In addition to being responsible for making us aware of our external environment and ourselves, the nervous system is also responsible for actions that cannot be controlled voluntarily. system is also in charge of actions that cannot be controlled voluntarily, such as reflexes, the maintenance of basic biological functions such as reflexes, the maintenance of basic biological functions such as the heartbeat and the transmission of nervous information itself.

This system is divided into two subsystems. One is the central nervous system, consisting of the spinal cord and brain, and the other is the peripheral nervous system, consisting of nerves distributed throughout the body.

Its smallest units are the nerve cellsThe smallest units are the nerve cells, which are the neurons and glia cells, the latter being the most numerous. Neurons communicate with each other mainly through the exchange of molecules called neurotransmitters, which serve as "messengers" stimulating one or another type of reaction on the part of the neuron that receives them (although in exceptional cases the exchange of information is not chemical but electrical).

2. Endocrine system

This is one of the most important systems of the body, because it allows us to adapt to the environment and to the physical changes our organism goes through.

It is in charge of regulation of the organism by means of hormoneswhich are chemical substances that allow us to control the body's regulatory processes, starting, maintaining or ending them. These changes may be transitory (e.g., beginning to sweat more during a stressful experience) or of a more permanent nature (e.g., guiding the development of primary and secondary sexual characteristics during adolescence).

Among the functions carried out by the endocrine system are metabolism, the growth of the organism, the production of hormones and sex cells...

On the other hand, the endocrine system is constituted by all the glands of the human body: testicles, ovaries, pituitary gland, liver.... All these organs work in coordination with the nervous system, which stimulates or limits the production of hormones depending on the circumstances (and even recycles part of them using them as neurotransmitters).

3. Circulatory system

It consists of a structure made up of veins and arteries, through which the blood travels. This liquid is of fundamental importance to keep the organism alive, since nutrients extracted from food and oxygen captured from the air travel through it.

These substances end up in the cells, where chemical reactions take place that give them energy to keep them alive.

The main organ of this system is the heartThe main organ of this system is the heart, which works as if it were an engine allowing the blood to flow throughout the body. This organ has special cavities that prevent the blood in the veins from mixing with the blood in the arteries.

4. Digestive system

It is in charge of collecting and using nutrients. By means of physical and chemical processes, this system assimilates nutrients from the food, with which the biological functions can be maintained.

Digestion begins in the mouth, where food is chewed and mixed with saliva. It then passes into the esophagus to reach the stomach. There, through the actions of gastric acids, the food is broken down and reduced into simpler elements.

Once the food has been broken down, it passes into the intestines passes to the intestines, first to the small and then to the large intestines, where the villi of these organs absorb the food.where the villi of these organs absorb the nutrients that pass into the bloodstream.

What has not been able to take advantage of the food passes to the final parts of the intestine, which are the colon, the cecum and the rectum, waiting to receive the signal to be defecated.

5. Respiratory system

It is in charge of capturing oxygen and eliminating carbon dioxide.. Oxygen is introduced into the bloodstream so that the blood carries it to the cells and cellular respiration and metabolism can take place.

Carbon dioxide, which is the result of these cellular processes, is removed from the blood and expelled through the lungs and lungs. through the lungs and the rest of the respiratory system.

The body parts involved in respiration are the lungs, bronchi, pharynx, trachea, nose, diaphragm and larynx.

Breathing is a semi-reflexive process, i.e. we can partly control it.that is to say, we can control it in part, however, when we are sleeping for example, we continue breathing.

6. Excretory system

It is responsible for eliminating from the organism those substances that may be harmful, which have beenwhich have been introduced through food or are the result of metabolic processes.

To eliminate unusable substances, the excretory system has two ways. On the one hand, by means of the sweat glands, it can eliminate pathogens and waste products through sweat. On the other hand, through the kidneys, which filter the blood and remove what may be toxic, urine is formed, through which what is not beneficial to the body is eliminated.

7. Reproductive system

It is responsible for the procreation of the species.. There are differences in the morphology of this system depending on the sex.

The male reproductive system consists of testicles, which are responsible for producing sperm.

During intercourse, the penis is first hardened by sending blood to it and making it erect. Once this is done, this organ is introduced into the woman's vagina in order to expel semen, a liquid containing spermatozoa and nutrients to keep them alive.

In the case of the female sex, the main sex glands are the ovaries, which are responsible for producing eggs. These descend through the fallopian tubes once a month, waiting to be fertilized. If fertilization does not occur, they are eliminated during menstruation.

If a sperm manages to reach the egg, fertilization occurs.. A zygote will be formed, which nine months later will be a fully formed baby.

8. Muscular system

It is formed by about 600 musclesdivided into three types:

Skeletal muscles

They are attached to the bone and are involved in voluntary movement.

Smooth muscles

They are found in the organs, such as thesuch as the intestine and stomach, allowing the movement of substances.

Cardiac muscles

They allow the blood to be transported through the movement of the heart.

9. Skeletal system

It is made up of about 200 bones and, together with the muscular system, form the locomotor system, involved in voluntary movement.

The bones, besides serving as support for the organism, manufacture blood cells and are an important storehouse of calcium.

10. Immune system

Responsible for the body's defense against pathogens, i.e. viruses, bacteria and bacteria.i.e. viruses, bacteria and other elements harmful to the body.

Its objective is to identify intruders, pursue, attack and eliminate them by means of white blood cells, which are produced in the lymph nodes, thymus, spleen and bone marrow.

When a pathogen is detected, several biological processes are activated as an alarm, such as inflammation and production of mucus and pus.

11. Lymphatic system

It is made up of the lymph nodes, as well as the ducts and vessels through which the lymph travels.. In other words, the main components of the lymphatic system are the lymph nodes and a network of ducts that interconnect them.

Lymph is a substance in which the white blood cells involved in the defense of the organism are found. It is therefore closely related to the immune system, of which, depending on the criteria we adopt, it can be considered part. However, the lymphatic system has functions beyond the body's response to infectious agents.

For example, lymph transports part of the fats in the body, and at the same time, the interconnected networks of the lymphatic system participate in the drainage of interstitial fluid, absorbing excess fluids from the capillaries.

Thus, it is possible to differentiate between the lymphatic system and the immune system by the fact that the former deals with processes that have nothing to do with the defense of the organism, among other things.

12. Integumentary system

It is constituted by the largest organ of the human body: the skin.. It is also made up of the nails, the hair and all the hair of the body in general.

Its function is to protect the body from external agents, as well as to maintain a constant temperature in the best possible way. By means of perspiration, in summer it lowers the temperature through perspiration that remains fixed for a period of time thanks to the hair, while in winter it prevents heat loss by insulating from the outside through a layer of cells (the outermost part of which is composed of dead cells).