Fish belong to vertebrates. Such organisms have a skull, a spine and paired extremities, in this case fins. The Fish class is divided into two classes:
The class of bone fish, in turn, is divided into several suborder:
- Cartilaginous ganoid.
- Dog firing.
- Bony fishes.
The main difference of all fish is the presence of one circle of blood circulation, as well as a two-chambered heart that is filled with venous blood, except for only cysteper and lungfish. The structure of the circulatory system of fish (bone and cartilaginous) is similar, but still has some differences. Below we will consider both schemes.
The circulatory system of cartilaginous fishes
The heart of cartilaginous fish is composed of two parts cameras. These cameras are called this way: the ventricle and the atrium. Near the atrium is a thin-walled venous sinus, it joins the venous blood. The end (if viewed from the side of blood flow) part of the ventricle is the arterial cone, which is part of the ventricle, but it looks like the beginning of the abdominal aorta. In all parts of the heart is cross-striped muscles.
The abdominal aorta departs from the arterial cone. Five pairs of gill arteries originate from the abdominal aorta and extend to the gills. Arteries, in which blood flows to the side of the branchial petals, are called the gill arteries, and in which the oxidized blood from the gill lobes flows, the outgoing gill arteries.
Bearing arteries flow into the roots of the aorta, and they, in turn, merge and form the dorsal aorta - the main arterial trunk. It is under the spine and supplies blood to all the internal organs of the fish. From the roots of the aorta to the head stretch the carotid artery.
From the head, the venous blood flows through the pair of cardinal veins, which are also called jugular. Blood from the trunk flows down the paired rear cardinal veins. They near the heart merge with the jugular veins and form the cuvier ducts of the corresponding side, then flow into the venous sinus.
In the kidneys, the cardinal veins form the so-called collateral circulation system. In the subcortical vein, blood comes from the intestine. In the liver, the portal circulatory system is formed: the intestinal vein brings blood, and the hepatic vein carries it into the venous sinus.
Circulatory system of bone fish
Almost all species of bony fish abdominal aorta has a swelling, which is called the arterial bulb. It consists of smooth muscles, but similar in appearance to the arterial cone of the circulatory system of cartilaginous fishes. It should be noted that the arterial bulb can't throb.
Arterial arches (bringing and taking out arteries) only four pairs. In most species of bony fishes, the venous system is arranged so that the right cardinal vein is continuous, and the left one forms a gateway system of circulatory circulation in the left kidney.
The circulatory system of fish is arranged simpler than that of amphibians and reptiles, but it has some primordia of vessels like frogs and snakes.
Considering how the circulatory system of fish is arranged, it is worth paying special attention to lungfish, because they have some peculiarities.
The most important feature of this intestine is the presence, in addition to the gill respiration, of the pulmonary. As the organs for pulmonary respiration, one or two bubbles protrude from the esophagus on the ventral side. But these formations are not similar in structure to the swimming bladder of teleost fishes.
Blood flows to the lungs through vessels that branch from the fourth pair of Gill arteries. They are similar in structure to the pulmonary arteries. From the so-called light going vessels. As it enters the blood in the heart. These special vessels are homologous in structure of the pulmonary veins of terrestrial animals.
The auricle is partially divided by a small septum into the right and left parts. From the pulmonary veins, the blood enters the left half of the atrium, and all the blood from the posterior vena cava and the ducts of the Cuvierian veins into the right half. The vena cava is absent in fish, it is characteristic only for terrestrial species of animals.
The circulatory system of fishes of an orderly frog The evaporation is evolved and is a harbinger of the development of this system of terrestrial vertebrates.
Composition of blood
- Colorless liquid - plasma.
- Erythrocytes are red blood cells. They contain hemoglobin, which stains blood in red. These same elements carry oxygen by blood.
- White blood cells are white blood cells. They take part in the destruction of foreign microorganisms that have got into the animal's body.
- Platelets affect blood clotting.
- Other elements of blood.
The relative mass of blood to body weight in fish is about 2-7%. This is the smallest percentage among all vertebrates.
The value of the circulatory system multifunction. The tissue, organs and cells of a living organism receive oxygen, minerals, fluid. Blood makes some products of metabolism: carbon dioxide, slag, etc.
It is worth noting that the mediator between the blood and tissues is the lymphatic system. The lymphatic system is a system of vessels in which a colorless liquid called lymph is contained.
Blood refers to connective tissue. It penetrates into the bloodstream from the intercellular space. The circulatory system of fish differs little from other vertebrates.