The Gill arch of the fish. Function of Gill arches

The Way of breathing in fish is of two types: air and water. These differences arose and were perfected in the process of evolution, under the influence of various external factors. If fish are the only type of breathing, the process is implemented with the help of the skin and gills. Fish with air-type breathing process is carried out using nadzhabernoy organs, swim bladder, intestine and through the skin. The main organs of respiration are gills, and the rest auxiliary. However, it is not always the auxiliary or additional bodies have a minor role, most often they are the most important.

Species of breathing fish

The Cartilaginous and bony fish have different structure of the Gill covers. So, first have a septum in the Gill slits, which ensures the opening of the gills out of separate holes. These partitions are covered with Gill petals strewn in turn, the network of blood vessels. This structure of the Gill covers, well illustrated by the rays and sharks.

At the same time, bony types of data partitions are reduced as unnecessary, as the Gill cover is movable in itself. The Gill arch of the fish function as a support, on which are the Gill filaments.

Functions of the gills. Gill arch

The main function of the gills is gas exchange. They absorbed oxygen from the water, and it is the carbon dioxide (carbon dioxide). But few know that the gills also help fish share the water-salt substances. So, after processing in the environment of excreted urea, ammonia, a salt exchange occurs between the water and the fish, first and foremost, this applies to sodium ions.

In the process of evolution and modification of sub-groups of the fish Gill apparatus was also changed. Thus, in bony fishes the gills have the form of scallops, they are composed of cartilaginous plates, and the cyclostomes have a saccular shape of the gills. Depending on the structure of the respiratory apparatus is different and the structure and function of the Gill arch of fishes.

Structure

The Gills are on the sides of the respective cavities of the bony fishes and are protected by caps. Each Gill consists of five arcs. Four of the Gill arch is completely developed and one rudimentary. On the external side of the Gill arc more convex, side of the arcs depart Gill filaments, which are cartilaginous rays. Gill arch serves as an anchor for the attachment of the petals, which are kept on them to your base to their base, and the free edges diverge inwards and outwards at an acute angle. On the Gill lobes are so-called secondary plates, which are located across the petal (or petals as they are called). On the gills there are a huge number of petals, different fish can be from 14 to 35 one millimeter at a height of less than 200 microns. They are so small in size that their width does not reach up to 20 microns.

The Main function of the Gill arches

Gill arch of vertebrates function as a filtering mechanism with the help of Gill rakers located on the arc facing in the oral cavity of the fish. This gives you the opportunity to hold in your mouth suspension in the water column, and nutrient microorganisms.

Depending on what feeds the fish, Gill stamens are also modified; they are based includes the bone plate. So, if a predator fish, then it stamens less and are located below, and the fish feed exclusively on plankton inhabiting the water column, the Gill stamens located high and thick. Those fish which are omnivorous, the stamens are average location between predators and planktoniella.

Circulatory system pulmonary circulation

The Gills of fish have a bright pink color due to the large amount of blood enriched with oxygen. This is due to the intense circulation process. The blood should be enriched with oxygen (venous), going from whole body fish and the abdominal aorta enters the Gill arch. The abdominal aorta divides into the two bronchial artery, followed by the Gill blood arc, which, in turn, is divided into a large number of flap arteries, enveloping Gill filaments located at the inner edge of the cartilaginous rays. But that's not the limit. Flap artery themselves are divided into a great number of capillaries, enveloping the thick mesh inner and the outer part of the petals. The diameter of the capillaries is so small that is equal to the value of the erythrocyte, transporting oxygen in the blood. Thus, the Gill arch function as a support for the stamens, ensuring the gas exchange.

On the other hand, all the petals of the regional arterioles merge into a single vessel that flows into a vein, carrying blood, which, in turn, passes into the bronchial, and then in the dorsal aorta.

If more detailed consideration of the Gill arch of the fish and carry out histological examination, it is best to examine the longitudinal slice. So will see not only the stamens and petals, but respiratory folds, which are the barrier between water and blood.

These folds are lined by only one layer of the epithelium and inside the capillaries, supported by Pilar-cells (reference). The barrier of the capillaries and the respiratory cells extremely vulnerable to the effects of the environment. If in water there are impurities of toxic substances, these walls swell, detachment occurs, and they thicken. It is fraught with serious consequences, such as impeding the process of gas exchange in the blood, which eventually leads to hypoxia.

Gas exchange in fish

The production of oxygen in fish occurs by passive gas exchange. The main condition for the enrichment of blood with oxygen is continuous flow of water in the gills, and this requires that the Gill arc and the whole apparatus kept the structure and function of Gill arches in fish will not be disturbed. The diffuse surface also must retain its integrity for proper enrichment of hemoglobin with oxygen.

For the implementation of passive gas exchange of the blood in the capillaries of fish moving in the opposite direction to the flow of blood in the gills. This feature contributes to the almost complete extraction of oxygen from water and the enrichment of the blood. In some birds, the rate of enrichment of blood on the composition of oxygen in water is 80%. The flow of water through the gills is due to pumping it through the Gill cavity, while the main function of the movement of the jaw apparatus and Gill covers.

What determines the breathing rate of fish?

Due to its characteristic features it is possible to calculate the respiratory rate of fish, which depends on the movement of the Gill covers. The concentration of oxygen in water and carbon dioxide in the blood affect the breathing rate of fish. Moreover, these aquatic animals are more sensitive to low concentrations of oxygen than the large amount of carbon dioxide in the blood. The respiratory rate is also affected by water temperature, pH and many other factors.

The fish Have a peculiar ability to extract foreign substances from the surface of the Gill arches and cavities. This ability is called cough. Gill covers are periodically covered and with a reverse movement of water suspension, located on the gills, washed with water current. This expression in fish is more often observed, if the water is contaminated with sediment or toxic substances.

Additional functions to the gills

In Addition to the main, respiratory, gills perform osmoregulation and excretory functions. Fish are ammonialike organisms, in fact, like all animals that live in water. This means that the ultimate breakdown product of nitrogen containing in the body is ammonia. Thanks it is secreted from the gills of the fish body in the form of ammonium ions, thus cleansing the body. In addition to oxygen, through gills in the blood, resulting in passive diffusion, comes salt, low molecular weight compounds, as well as a large number of inorganic ions in the water column. In addition to the gills, absorption of these substances by using special structures.

This includes specific chloride cells that perform the function of osmoregulation. They are able to move ions of chlorine and sodium, while moving in the direction opposite to the large diffusion gradient.

The Movement of chloride ions depends on the fish habitat. Thus, freshwater species of monovalent ions, chloride cells are transferred from water into the blood, replacing those that were lost as a result of the functioning of the excretory system of fish. But the marine fish, the process is carried out in the opposite direction: the selection occurs from the blood to the environment.

If the water is markedly increased concentration of malicious chemical elements, the auxiliary osmoregulatory function of the gills may be compromised. As a result, the blood comes not for the amount of substance, which is necessary, and a much greater concentration that may be detrimental to the animals. This specificity does not always bear negative character. So, knowing this peculiarity of the gills, it is possible to fight many diseases of fish, making medicines and vaccines directly into the water.

Skin breathing different fish

Absolutely all fish have the capacity for cutaneous respiration. That's just the extent to which it is developed dependsfrom a large number of factors: age, environmental conditions, and many others. So if the fish lives in clean running water, the percentage of dermal respiration is negligible and is only 2-10 %, while the respiratory function of the embryo is carried out exclusively through the skin and vascular system of the bile bag.

Intestinal breath

Depending on the environment changes the way of breathing of the fish. So, catfish and tropical fish sunovia actively breathing with the help of the intestine. Air if swallowed, gets in there and with the help of a dense network of blood vessels into the blood. This method began to develop in fish in connection with the specific conditions of the environment. Water in their reservoirs, in connection with high temperatures, has a low oxygen concentration, which is aggravated by the absence of turbidity and currents. The result of evolutionary transformation of fish in these waters have learned to survive using oxygen from the air.

Additional function of the swim bladder

The swim bladder is designed for hydrostatic regulation. This is its main function. However, some species of fish swim bladder is fit for breathing. It is used as a reservoir for air.

Types and structure of the swim bladder

Depending on the anatomical structure of the swim bladder of all fish species are divided into:

• Otkratougolnah;
• Secretornah.

The First group is most numerous and is the main one, while the group secretornah fish are very small. It includes, perches, mullets, cod, stickleback and others At atkritumu fish, as the name suggests, the swim bladder is open for communication with the main intestinal flow, and secretornah, respectively.

Carp also have the specific structure of the swim bladder. It is divided into rear and front cameras, which connect the narrow and short channel. The walls of the anterior chamber of the bladder is composed of two shells, outer and inner, while the back camera is no exterior.

The swim bladder is Lined by one row of flat epithelium, after which is a row of loose connective, muscle and a layer of vascular tissue. The swim bladder has a natural pearlescent glow that is provided by a special dense connective tissue, having a fibrous structure. To ensure the safety bubble outside of both cells is covered with an elastic serous membrane.

Labyrinth organ

A small number of tropical fish developed a special organ, like bettas, gouramis and nadzhabernoy. To this type belong makropody, gourami, bettas, and snakeheads. Education can be observed in the changes of the pharynx, which transformirovalsya in nadzhabernoy body or sticks out of the Gill cavity (called the labyrinth organ). Their main purpose - the opportunity of obtaining oxygen from the air.