Circulatory system of fish: cartilage and bone
Fish are vertebrates. Such organisms have a skull, spine and paired limbs, in this case fins. The Pisces class is divided into two classes:
- Bone fish.
- Cartilaginous fish.
The class bony fish, in turn, is subdivided into several super-detachments:
- Cartilage ganoids.
- Lungfish fish.
- Cistepere fish.
- Bony fish.
The main difference of all fish is the presence of one circle of blood circulation, as well as a two-chamber heart, which is filled with venous blood, with the exception of only cross-shaped and double-breathing fishes. The structure of the circulatory system of fish (bone and cartilage) is similar, but still has some differences. Below will be considered both schemes.
Circulatory system of cartilage fish
The heart of cartilaginous fish consists of two parts - chambers. These cells are called: ventricle and atrium. Near the atrium is a wide thin-walled venous sinus, venous blood is infused into it. The end (as viewed from the blood flow) part of the ventricle has an arterial cone, which is part of the ventricle, but looks like the beginning of the abdominal aorta.In all parts of the heart is striated muscle.
The abdominal aorta moves away from the arterial cone. Five pairs of gill arteries originate from the abdominal aorta and depart to the gills. Arteries in which blood flows towards the gill filaments are called the gill-bearing arteries, and in which oxidized blood flows from the gill lobes — the outgoing gill arteries.
The carrying arteries fall into the roots of the aorta, and they, in turn, merge and form the dorsal aorta - the main arterial trunk. It is located under the spine and supplies blood to all the internal organs of the fish. From the aortic roots to the head, the carotid arteries stretch.
From the head, venous blood flows through the paired cardinal veins, which are also called jugular. The blood from the trunk flows through the paired posterior cardinal veins. Near the heart they 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 portal blood circulation system. In the intestinal vein, blood flows 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
In almost all types of bone fish, the abdominal aorta has a bulge, which is called an arterial bulb. It consists of smooth muscles, but outwardly similar to the arterial cone of the circulatory system of cartilage fish. It should be noted that the arterial bulb cannot pulsate on its own.
There are only four pairs of arterial arcs (bringing and carrying out arteries). In most species of bony fish, the venous system is designed so that the right cardinal vein is continuous, and the left one forms the portal system of the blood circulation in the left kidney.
The circulatory system of fish is simpler than that of amphibians and reptiles, but it has some rudimentary vessels like frogs and snakes.
Considering how the circulatory system of fish is arranged, it is worthwhile to pay special attention to the short-breathing, since they have some peculiarities.
The most important feature of this supra-order is the presence of pulmonary, besides gill respiration. The organs for pulmonary respiration are one or two bladders that open near the esophagus on the ventral side. But these formations are not similar in structure to the swimming bladder of bony fishes.
Blood flows into the lungs through the vessels, which branch off from the fourth pair of gill arteries. They are similar in structure to the pulmonary arteries. From the so-called lungs are vessels. According to him, the blood enters the heart. These special vessels are homologous in structure to the pulmonary veins of land animals.
The atrium is partially divided by a small partition into the right and left parts. From the pulmonary veins, blood enters the left half of the atrium, and all the blood from the posterior vena cava and the Cuvier ducts into the right half. The vena cava is absent in fish; it is characteristic only for terrestrial animal species.
The circulatory system of the fish of the superorder is Laconstriated, evolved and is a precursor of the development of this system of terrestrial vertebrates.
- Colorless liquid - plasma.
- Red blood cells - red blood cells. They contain hemoglobin, which dyes the blood red. These same elements carry oxygen through the blood.
- White blood cells are white blood cells. Take part in the destruction of foreign microorganisms in the body of the animal.
- Platelets affect blood clotting.
- Other elements of blood.
The relative weight of blood to body weight in fish is about 2-7%. This is the smallest percentage of all vertebrates.
The value of the circulatory system is multifunctional. Thanks to her, tissues, organs and cells of a living organism receive oxygen, minerals, and liquid. The blood makes some metabolic products: carbon dioxide gas, slags, etc.
It is worth noting that the lymphatic system acts as a mediator between the blood and tissues. The lymphatic system is a system of blood vessels that contains a colorless liquid called lymph.