The excretory system has the function of eliminating the residues of the chemical reactions that occur inside the cells, in the process of metabolism.
In this way, many substances that are not used in the body, especially toxic ones, are excreted from the body.
It is important to emphasize that the excretory system is responsible for much more than just the elimination of waste. It is primarily responsible for controlling the chemical composition of the internal environment.
How does the excretory system work?
Urine is excreted by the kidneys
The elimination of harmful substances or those that are in excess in our body is called excretion, a process that allows the internal balance of our organism.
The products of excretion are called “excreta”, which are released from the cells into the fluid that bathes them (interstitial fluid), and from there are passed into the lymph and blood.
In the process of degradation of carbohydrates and lipids, carbon dioxide and water are produced. Proteins are also metabolized, and their metabolism results in substances that are harmful to the body, including carbon dioxide and nitrogenous products, such as ammonia, urea and uric acid.
There is also water and mineral salts, especially sodium chloride (the main component of table salt).
To eliminate these substances, excretion is carried out through urine, breathing and sweat. Understand, in the sequence, how the excretion of this waste is made.
See also: Metabolism
Urine Excretion
Excretion through the urine starts in a process carried out by the kidneys. They work as a filter that retains impurities in the blood and leaves it in a position to circulate through the body.
The kidneys participate in the control of plasma concentrations of ions, such as sodium, potassium, bicarbonate, calcium and chlorides.
According to the concentrations in the blood, these ions can be eliminated in greater or lesser amounts in the urine, through the urinary system. The main substances that form urine are urea, uric acid and ammonia.
Expand your knowledge and also read about:
- urea cycle
- Urinary system
Carbon dioxide excretion
Breathing is essential for the excretion of carbon dioxide.
The excretion of carbon dioxide is carried out through the organs of the respiratory system. The elimination of this element is the final product of the metabolism of carbohydrates (carbohydrates or sugars) and lipids (fats) in the process of cellular respiration.
In addition, water is also eliminated in the form of steam, through exhalation.
Know more about:
- Cellular respiration
- Krebs Cycle
- Respiratory system
Sweat Excretion
Sweat glands are responsible for excreting sweat
Sweat production is not related to the excretion process, but to temperature regulation in the body.
However, mineral salts, such as sodium chloride, and water are eliminated through sweat and, due to its enormous importance for the cell, it is largely conserved in the body.
Also read about:
- sweat glands
- endocrine system
Organs that act in the excretory system
To eliminate waste from the chemical reactions that our body produces, different organs perform extremely important functions.
Find out below what these organs are and how they act in the excretory system.
Rins
The kidneys are organs of the urinary system, but they act directly in the elimination of residues that result from the action of the organism’s metabolism.
Considering the substances eliminated by the kidneys, urea, creatine and blood toxins stand out.
In addition to this function, it also acts in regulating the volume of fluids in the body and in controlling blood pressure.
See also: kidneys
Nefrons
Nephrons are structures present in the kidneys and whose main action is the formation of urine. It filters elements from blood plasma and then eliminates them in the urine.
Located in the kidneys, they are present in large quantities in the human body, with approximately 1,200,000 nephrons in each kidney.
See also: nephron
ureters
The ureter is a tube that connects the kidney to the bladder, that is, it transports urine from the kidneys to the bladder, with one ureter for each kidney. He is one of the elements of the urinary system and that help in the excretion of unwanted substances.
To perform its function, it performs peristaltic movements that help conduct urine to the bladder. For this, its wall is formed by three different layers, which are formed by a mucous layer, a muscular layer and an adventitia layer.
See also: Human Body Tissues
Urinary bladder
The urinary bladder is the organ responsible for storing the urine produced by the kidneys and transported by the ureters. In addition to storage, she is the one who eliminates the urine.
This is a muscular organ with a high elastic capacity, as it can store up to 800 ml of urine.
See also: human skin
urethra
The urethra is the channel responsible for carrying the urine out of the body. It is connected to the urinary bladder.
In men, the urethra ends at the penis, in women it ends at the vulva.