Circulatory System of a Rat

Rats are rodents belonging to the superfamily Muroidea. The circulatory system of a rat greatly resembles that of humans and other mammals. The circulatory system is responsible for circulating blood and nutrients throughout the entire body.

Circulatory System of a Rat
A rat's circulatory system consists of a heart, blood and blood vessels. The function of blood vessels is to facilitate the circulation of blood and nutrients across the body. Like human beings, the heart of a rat consists of four chambers. The top two chambers are called right and left atrium, while the bottom two chambers are known as right and left ventricle. The constituents of blood are plasma and blood cells. Blood cells are of two types, white and red blood cells. The white blood cells are an indispensable part of the body's immune system, while the red blood cells contain hemoglobin, which transports oxygen to different regions of the body. The blood is circulated within the body with the help of arteries and veins. The arteries carry oxygenated blood from the heart to the rest of the body, while the veins return deoxygenated blood from the different parts of the body to the heart.

Blood Circulation in Rats
The circulatory system includes both pulmonary and systemic circulation. Pulmonary circulation refers to the circulation of blood between heart and lungs, while systemic circulation is the circulation of blood between heart and rest of the body, excluding the lungs.

The deoxygenated or oxygen-deprived blood from the entire body is carried by the veins. All veins terminate into three main large veins, known as right superior vena cava, left superior vena cava and inferior vena cava. The right and left superior vena cava are responsible for carrying blood from the right and left sides of the head and neck, while the inferior vena cava brings deoxygenated blood from the lower regions of the body to the heart. They enter the right atrium of the heart to deposit the deoxygenated blood. From the right atrium, the blood is pumped into the right ventricle through the tricuspid valve. Then it is pumped out into the pulmonary trunk, which branches off into the right and left pulmonary arteries, which carry the deoxygenated blood to the lungs, for purification. This whole process is known as pulmonary circulation.

In the lungs, the blood gets oxygenated, and then it is carried to the left atrium of the heart by the right and left pulmonary veins. From the left atrium, it is pumped into the left ventricle via bicuspid valve, from where it enter the aorta through the aortic semilunar valve. Now the aorta divides into two parts, innominate artery and aortic arch. The aortic arch is the portion where the aorta bends to the left. The innominate artery branches off into the right common carotid artery and right subclavian artery, while the aortic arch branches into the left common carotid artery and left subclavian artery. The right common carotid artery supplies oxygenated blood to the right anterior part of the brain and neck, while the right subclavian artery transports blood to the right shoulder and arms or forelegs. On the other hand, left common carotid artery channels blood to the left side of the neck, while the left subclavian artery is responsible for carrying it to the left shoulder and arms. The main aorta continues as dorsal aorta, supplying blood to the lower regions of the body. This process is called systemic circulation.

The normal functioning of the entire circulatory system mainly depends upon the health and vigor of the pumping organ, that is heart and the blood vessels. Besides these, the lungs also play a significant part by supplying much needed oxygen to the blood, to be circulated to the entire body, without which the vital metabolic activities within the body will come to a standstill.