Fish Circulatory System

The circulatory system is an organ system that passes nutrients (such as amino acids, electrolytes and lymph), gases, hormones, blood cells, etc. to and from cells in the body to help fight diseases and help stabilize body temperature and pH to maintain homeostasis.

Fish are cold-blooded vertebrates water and can be found in both fresh and saline water. The circulatory system of fish, is responsible for transporting blood and nutrients throughout the body. It has a closed circulatory system, ie, the blood travels through the body through the blood vessel network. Unlike humans, fish have single cycle circulation, where oxygen deprived blood reaches the heart, where it is pumped to the brim and distributed throughout the body. Furthermore, in mammals, oxygenated blood enters the heart, where it is pumped to the lungs for oxygenation. Then, oxygenated blood returns to heart from the lungs to be transported through the body. 

The circulatory system of a fish 

The circulatory system of fish is very simple. Like mammals, the circulatory system of fish consists of a heart, vessels, blood and blood. The heart of a fish is a simple muscular structure that lies between the posterior gill arches. It is surrounded by the pericardial membrane or pericardium. In most fish, the heart is composed of an atrium, ventricle, a sac-like structure known as thin-walled venous sinus and a tube called a bulbous arteriosus. Although it has four parts, the heart of a fish is considered two cameras. 

Blood contains plasma (the liquid portion of blood) and blood cells. The red blood cells or red blood cells contain hemoglobin, a protein that helps transport oxygen throughout the body, while the white blood cells are an indispensable part of the immune system. The thromocytes perform functions that is equivalent to the role played by platelets in the human body, ie, that aid in blood clotting. The blood circulates throughout the body with the help of blood vessels. Blood vessels are of two types, arteries and veins. Arteries are responsible for carrying oxygenated blood from the heart to the body, while veins return deoxygenated blood from different parts of the body to the heart. 


In fish, blood without oxygen or oxygen deprived, is transported through the veins to the venous sinus. Venous sinus is an important component of the circulatory system of lower vertebrates. The deoxygenated blood through the veins collected accumulates in the venous sinus before entering the heart. First blood enters the atrium of the heart, which is a great camera. Then it enters the ventricle, where it is pumped into the tube, bulbous arteriosus. Through bulb arteriosus, the blood reaches the aorta and the gills. The gills are the respiratory organ of a fish and run the activities of human lungs. The exchange of gases, ie oxygen uptake of water and carbon dioxide removal. Then, oxygenated blood is transported throughout the body with the help of blood vessels. Blood facilitates the transport of oxygen and nutrients. It also collects carbon dioxide is transported back to the heart and then to the gills, which leaves the body. 

Although the circulatory system of fish is quite simple compared to that of humans and other mammals, it serves an important purpose, illustrating the different stages of evolution of the circulatory system in animals. His heart is also studied to learn the progressive evolution of the four-chambered heart.

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