Excretory system functions and parts (organs)

The excretory system It is the set of organs in our body that is responsible for excretion, that is, the elimination of metabolic waste products to the outside. This system is made up of various organs of our body that perform excretory functions; The most recognized of these are the kidneys and urinary system, but the lungs, skin, and intestines also have important excretory functions..

Every day our body needs to receive oxygen, nutrients and fluids to hydrate and feed the cells that make up its tissues and organs. However, not everything that is in food, fluids and air that enters our body is fully used, and what cannot be used or what results from metabolism is what is known as material. or waste product.

The main wastes that are produced in our body are urine, feces, sweat and the carbon dioxide (CO₂) that we exhale, which are actually the sum of the metabolic waste produced at the level of each of our cells as a result. of the processing of carbohydrates, proteins, lipids and fats, etc..

The elimination of all these wastes is very important for our health, since many times these materials contain certain molecules that, if they accumulate, can make us feel bad or cause us some diseases; it is the elimination of these molecules that the organs of excretion are responsible for.

Functions of the excretory system

The excretory system has various functions and all of them are essential for the proper functioning of our body. Among some of them the following can be distinguished:

- Eliminate excess fluids and with them toxins and some waste molecules that are extracted from the blood when it is “filtered” (urea, uric acid, ammonia, etc.).

- Maintain the osmoregulation of our body, which is nothing more than the regulation of fluid and salt levels.

- Prevent dehydration.

- Eliminate medications, drugs or other substances that the body receives from the body.

- Regulate body temperature and excess electrolytes.

- Get rid of solid waste that results from the digestion of food, which represents all the non-assimilable or unabsorbed materials of what we eat

- Expel carbon dioxide from the body (produced during cellular respiration).

Parts of the excretory system (organs)

For the excretion of urine

The kidneys are the main organs of excretion in the body. These are part of the urinary system and other structures / organs such as the ureters, the urinary bladder and the urethra participate in their functions..

In our body there are two kidneys, which are the size of a fist and which are located on each side of our spine, more or less at the same level as the liver (just below the diaphragm).

These small organs are responsible for filtering the blood and for the production of some substances that regulate different internal aspects of our body (hormones). The products that are filtered from the blood are eliminated with the urine.

The ureters are tubes that are responsible for directing urine from the kidneys to the urinary bladder, which is an organ in the form of a "sac" where urine is stored until it is excreted outside the body when we urinate (a process called urination).

The elimination of urine occurs through another tube called the urethra, which is connected to the urinary bladder at one end and to a sphincter (a valve) at the other..

For the excretion of solids (feces)

The digestive system performs very special functions during the excretion of waste. In the intestines, everything that is not digested derived from food is eliminated as fecal matter..

A couple of very important glandular organs participate in this system, which are responsible for excreting many substances into the intestines that facilitate the digestion of what we eat. These organs are the liver and pancreas.

For the excretion of CO₂

The respiratory system comprises the organs that are responsible for the excretion of carbon dioxide (CO₂) produced by the respiration of our cells..

Its function is dual: on the one hand, it allows the entry of oxygenated air into our body when we inhale, where oxygen is delivered to the blood. On the other hand, it receives from the blood the CO₂ that is produced by the cells during respiration and eliminates it when we exhale..

For fluid excretion and temperature regulation

The skin is the largest organ in our body. In addition to protecting everything we have inside and helping us to perceive some sensations such as touch, cold and heat, this organ is responsible for the fundamental process of sweating.

Sweating not only works in the elimination of excess fluids, but also participates in the regulation of electrolyte balance and - most important of all - of body temperature, especially in conditions of high temperatures, internal or external..

These functions are possible thanks to the existence, under our skin, of small structures known as sweat glands..

How does the excretory system?

Let's see in a little more detail how the excretory system of the kidneys works, which is responsible for the elimination of metabolic waste products through the urine..

1- Cell metabolism

All the cells of our body constantly receive nutrients, which they must metabolize. Much of these nutrients are used for energy, but wastes are also produced that must be eliminated, since they can be harmful if they accumulate excessively.

Cells in tissues shed their waste into the space around them, which is known as the extracellular space. These wastes then reach the blood plasma and it is in the elimination of these wastes that the excretory system of the kidneys participates..

Generally, these waste molecules are soluble in water, which is why it is used in our body, among other things as a vehicle for the transport and elimination of cellular metabolic waste..

2- The blood and kidneys

All the blood in the body passes through the kidneys successively during the day and the kidneys are perfectly designed to filter all the blood they receive: inside there are hundreds of small filtering structures called nephrons.

The heart pumps blood to the kidneys through the renal arteries; When this blood reaches the kidneys, it is first conducted into them through small capillaries and later towards the glomeruli, which are the filtering structures inside each nephron..

There is a lot of pressure in the glomeruli, which allows a portion of fluid with the waste molecules to be drawn from the blood.

This liquid is known as filtered out and it is from which the harmful molecules will be extracted and from where some molecules will be reabsorbed that should not be discarded in their passage through the rest of the kidney structure.

3- Reabsorption and concentration

Although the kidneys are mainly responsible for filtering and eliminating metabolic waste contained in the blood, they also participate in the process of reabsorption of water, salts, ions, proteins and carbohydrates found in the filtrate..

Therefore, what is excreted is only a small percentage of everything that passes through the filtering structures of the kidney, which is also highly concentrated, since a large part of the water it contains is removed..

4- Formation of urine

Through a rather long and complicated process, the filtrate becomes urine and this is conducted through the ureters to the bladder, where it is stored until we "decide" to urinate, which implies that the bladder empties into the urethra and there it is expelled from our body.

References

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