Selection organs. Scheme of the organs

Isolation is the removal from the body of toxins formed as a result of metabolism. This process is a necessary condition for maintaining the consistency of its internal environment - homeostasis. The names of the organs for the allocation of animals are diverse - specialized tubules, metanephridia. A person has a whole mechanism for this process.

Selection system

Exchange processes are quite complex and occur at all levels - from molecular to organism. Therefore, for their implementation, a whole system is needed. The organs of human secretion excrete various substances.

Surplus water is removed from the body with the help of the lungs, skin, intestines and kidneys. Salts of heavy metals secrete the liver and intestines.

Lungs are respiratory organs, the essence of which is the intake of oxygen into the body and the removal of carbon dioxide from it. This process is of global importance. After all, carbon dioxide released by animals is used for photosynthesis. With carbon dioxide, water and light in the green parts of the plant that contain the chlorophyll pigment, they form a glucose and oxygen carbohydrate. Here such a vital cycle of substances in nature is obtained. Through the lungs, excess water is also continuously removed.

The intestine removes undigested remnants of food, and with them harmful metabolic products, which can cause poisoning of the body.

The digestive gland of the liver is a true filter for the human body. In it, poisonous substances are taken from the blood. The liver secretes a special enzyme - bile, which disgraces toxins and removes them from the body, including poisons of alcohol, drugs and drugs.

The Role of Skin in Selection Processes

All organs of excretion are irreplaceable. After all, if their functioning is disturbed, toxins will accumulate in the body. Particularly important in the implementation of this process is the largest human organ - the skin. One of its most important functions is the realization of thermoregulation. During intensive work, the body emits a lot of heat. Accumulating, it can cause overheating.

The skin regulates the intensity of the heat release, keeping only its required amount. Together with sweat, besides water, mineral salts, urea and ammonia are removed from the body.

How does heat exchange occur?

Man is a warm-blooded being. This means that the temperature of his body does not depend on the climatic conditions in which he lives or temporarily resides. Organic substances that come with food: proteins, fats, carbohydrates - in the digestive tract are split up to their constituents. They are called monomers. During this process, a large amount of thermal energy is released. Since the ambient temperature is often lower than body temperature (36.6 degrees), according to the laws of physics, the body gives an excess of heat to the environment, i.e. In the direction where it is less. Thus, the temperature equilibrium is maintained. The process of recoil and the formation of heat by the body is called thermoregulation.

When the person sweats most intensively? When it's hot outside. And in the cold season, sweat is almost not released. This is because the body is not beneficial to lose heat, when it is not very much.

The process of thermoregulation is influenced by the nervous system. For example, when palms sweat during the exam, it means that in a state of excitement, the vessels expand and the heat transfer increases.

Structure of the urinary system

An important role in the processes of isolation of metabolic products is played by the system of urinary organs. It consists of paired kidneys, ureters, a bladder, which opens outward with the urethra. The figure below (the scheme "Selection organs") illustrates the location of these organs.

Kidneys - the main organ of excretion

The organs of the allocation of the person begin with the kidneys. These are paired organs of the bean-shaped form. They are located in the abdominal cavity on both sides of the spine, which are turned to the concave side.

Outside, each of them is covered with a shell. Through a special indentation called the kidney gates, the organ includes blood vessels, nerve fibers and ureters.

The inner layer is formed by two kinds of substances: cortical (dark) and cerebral (light). In the kidney, urine is formed, which is collected in a special container - the pelvis, from it to the ureter.

Nephron is an elementary unit of the kidney

The organs of excretion, in particular the kidney, consist of elementary units of structure. It is in them that metabolic processes occur at the cellular level. Each kidney consists of a million nephrons - structural and functional units.

Each of them is formed by a renal calf, which, in turn, surrounds a goblet capsule with a ball of blood vessels. The urine is initially collected here. From each capsule pass the convoluted tubules of the first and second tubules, which open with collecting tubes.

The mechanism of urine formation

Urine is formed from the blood as a result of two processes: filtration and reabsorption. The first of these processes occurs in the bodies of the nephron. As a result of filtration from the blood plasma, all components except proteins are isolated. Thus, in the urine of a healthy person there should not be this substance. And its presence indicates a violation of metabolic processes. As a result of filtration, a liquid is formed, which is called primary urine. Its amount is 150 liters per day.

Then comes the next stage - reabsorption. Its essence lies in the fact that from the primary urine into the blood back are absorbed all the beneficial substances for the body: mineral salts, amino acids, glucose, a large amount of water. As a result, a secondary urine is formed - 1.5 liters per day. In this substance, a healthy person should not have glucose monosaccharide.

The secondary urine is 96% water. It also includes sodium, potassium and chlorine ions, urea and uric acid.

Reflex character of urination

From each nephron secondary urine enters the renal pelvis from which the ureter drains into the bladder. It is a muscular unpaired organ. The volume of the bladder increases with age and in an adult reaches 0.75 liters. Outside the bladder opens the urethra. At the output it is limited by two sphincters - circular muscles.

To have the urge to process the urination, the bubble should accumulate about 0.3 liters of fluid. When this happens, the receptors of the walls become irritated. The muscles contract, and the sphincters relax. Urination occurs arbitrarily, i.e. An adult person is able to control this process. It is regulated by urination with the help of the nervous system, its center is in the sacral region of the spinal cord.

Functions of the selection organs

Kidneys play an important role in the process of removing the final metabolic products from the body, regulate water-salt metabolism and maintain the constancy of the osmotic pressure of the body fluid.

The excretory organs purify the body of toxins, maintaining a stable level of substances necessary for the normal full functioning of the human body.