Excretory system: characteristics, parts and function.

An overview of the characteristics, biological functions and components of the excretory system.

Of all the systems of the human body, the excretory system may be one of the least popular, mainly due to the fact that it is responsible for eliminating what our body does not need.

The elimination of urine is no small matter, since it is a liquid that contains substances that, if stored for too long in our body, could lead to health problems such as poisoning.

Let's see what the excretory system is more in depthWhat are the parts that are involved in the process of elimination of urine and how this liquid is formed.

The excretory system

The excretory system, also known as the human urinary system, is a set of organs and other structures responsible for eliminating urine and sweat, which are liquids containing diluted substances that cannot be used by the human body.which are liquids containing diluted substances that cannot be used by the human body.

This system plays a fundamental role in the excretion of urine, since the accumulation of substances present in it can cause serious health problems, such as intoxication, infections and organ failure.

Maintaining a good hygiene and maintenance of this system, in addition to healthy eating habits, ensures optimal health conditions, in addition to avoiding diseases such as cystitis such as cystitis, kidney stones, nephritis and renal insufficiencies.

Parts of this system

Both kidneys and several excretory pathways are involved in the excretion process. In the following, we will detail these parts and explain their functions during the process of elimination of waste products..

Kidneys

These are two organs whose function is to filter the Blood and produce urine. filter the blood and produce urine.

The kidneys are located around the spinal column, at the level of the lumbar vertebrae, and are surrounded by adipose or fatty tissue that are surrounded by adipose or fatty tissue that keeps them at an adequate temperature and protects them from external impacts. and protect them from external impacts.

Their shape is similar to that of two beans, measuring 12 cm long, 5 cm long and 3 cm thick, weighing about 150 g each.

In its interior two zones can be distinguished. On one side we have the cortex, which is of a yellowish color and is located on the periphery of this organ and, on the other side, we have the medulla, which is more towards the interior and is reddish in color. Below the medulla and the cortex is the renal pelvis, which collects the urine.which collects the urine and directs it to the ureter. An artery enters this renal pelvis and a vein exits.

In the outer layer of the kidneys are found nephrons, which are very small filters composed of an extensive network of blood vessels that filter blood to form urine. that filter the blood in order to form urine. Three substructures are found in each nephron: the glomerulus of Malpighi, Bowman's capsule and the renal tubule.

The kidneys fulfill two fundamental functions for the survival of the organism. They act as regulatory organs, since they maintain optimal levels of nutrients such as salts and glucose in the blood, as well as having sufficient water so that they can be transported as efficiently as possible.

In addition to their regulatory function, they serve as the purifiers of the human bodyIn addition to their regulatory function, they serve as the purifiers of the human body, since they are responsible for extracting substances that can be harmful if stored in large quantities, such as urea, the main component of urine, and uric acid.

Kidney diseases and dysfunctions can be extremely harmful conditions for human beings. For this reason, they are one of the most frequently transplanted organs, since their incorrect functioning can lead to death.

Excretory tracts

These are ducts and cavities through which urine passes and is eliminated.. There are basically three: ureters, bladder and urethra.

1. Ureters

They consist of two long tubes that communicate the renal pelvis with the bladder.. They are composed of smooth muscle fiber and muscular epithelium, as well as nerve endings. These components are responsible for regulating the passage of urine into the bladder, propelling it.

The nerve endings are very sensitive, which is why people suffering from some type of obstruction such as a kidney stone feel a lot of pain.

2. Bladder

Along with the kidneys, this is possibly the best known part of the excretory system. It is a hollow organ where urine is stored, which arrives through the two ureters coming from the kidneys.

The bladder is an elastic organ, capable of modifying its size to be able to store a large amount of liquid, thanks to the fact that it is formed by muscular fiber walls thanks to the fact that it is formed by muscular fiber walls, which can provide it with a capacity of up to one liter.

Although the capacity of this organ can be very high, it is from 400 or 500 cubic centimeters of capacity when the urge to urinate is felt.

3. Urethra

This is the last conduit through which urine passes before it is eliminated. It is a tube that connects to the outside of the body and is located at the bottom of the bladder. It has two sphincters with muscular tissue that regulate the outflow of urine. which are responsible for regulating the outflow of urine.

There are differences in its structure depending on the sex. The female urethra is between 3 and 4 cm long, going from the base of the bladder to the labia minora, just in front of the vaginal opening. In the male case, the urethra can reach a length of 20 cm, distinguishing three parts: pelvic portion, membranous portion and spongy portion, the latter being the penis itself.

Sweat glands

Urea is not only excreted through the urine by the process we have explained. through the process we have explained. In addition to passing through the kidneys, ureters, bladder and urethra, urea can be eliminated through sweat, a liquid composed of water, mineral salts and some urea. In essence, this is more dilute urine.

In humans, the function of these glands is not only to eliminate substances. It also allows the body's temperature to be regulatedby allowing it to perspire by moistening the body's surface.

These glands are distributed all over the skin, but they are especially concentrated in the head, armpits and palms of the hands, which is why they are the main places where you sweat when you do sports activities or get nervous.

How is urine formed?

The blood is introduced into the kidneys, where the nephrons will be in charge of the nephrons will remove the waste products that are diluted in it, which can be harmful to the correct functioning of the organism, reaching for the correct functioning of the organism, becoming toxic.

There are three processes involved in the formation of urine:

1. Filtration

The blood reaches the nephron, where it will be filtered by Bowman's capsule. The substances that can be filtered here are of small size, excluding complex molecules and cells that can be found in the bloodstream such as platelets.

The liquid that remains as a result of this process is similar to blood plasma in its composition and may have beneficial substances for the body. in its composition and may contain substances beneficial to the body.

2. Reabsorption

The filtered liquid passes through the tubes of the nephron, being reabsorbed, but selecting usable substances to be but selecting substances that can be used to return to the bloodstream..

If this is the case, it will be necessary to reintroduce them into the bloodstream by means of active transport, which implies an expenditure of energy, in addition to using water from this plasma.

3. Secretion

Some substances that are not usable but have been reabsorbed in the wrong way are secreted from the blood capillaries to the interior of the nephron, finally obtaining urine.and finally urine is obtained.

Bibliographical references:

• Bard, J.; Vize, Peter D.; Woolf, A.S. (2003). The kidney: from normal development to congenital disease. Boston: Academic Press.
• Efren-Serrano, B. and Steve-Gomez, E. (2016) Basic urology for medical students. Loja, Ecuador: Universidad nacional de Loja.