Circulatory system in animals

Transportation of substances throughout the body is an essential requirement for the survival of living beings. Circulatory system comprises of blood, blood vessels and heart. Blood is an essential component of this system which helps in oxygen transport to various cells as well as waste removal from the body. Blood comprises of cells and fluid. Fluid part of blood is called plasma. Blood contains three types of cells. Circulatory System in Animals Homework Help for student in USA, UK, Australia

Red Blood Cells (RBC) which contains oxygen binding red pigment called haemoglobin.

White Blood Cells (WBC) which acts as defense line against diseases entering our body.

Platelets which help in blood clotting.

Blood Vessels are a network through which blood flows. Two different type of blood vessels included arteries and veins. Arteries are thick walled and they carry oxygenated blood form heart to different parts of the body where they branches further to form capillaries. Veins are thin walled that carries deoxygenated blood from different parts of the body back to heart.

Pumping House of Body: Heart

Heart is known as the pumping house of our body. Sized to a fist it is located in chest cavity with slightly left tilted lower side. Human heart is four chambered with two upper chambers called the atrium and two lower chambers are called the ventricles.

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Functioning of Circulatory System:

Human circulatory system comprises of two types of circulation - systemic and pulmonary(Fig7.4.1).

Systemic Circulation: In this type of circulation arteries carry oxygen rich blood from heart to different parts of body and veins carry carbon dioxide rich blood from different parts back to heart.


Pulmonary Circulation: In this type deoxygenated blood is carried by pulmonary artery to lung and oxygenated blood flows back from ling to heart through pulmonary vein.

Rhythmic contraction and relaxation of heart muscles give rise to heart beat which can be easily felt by placing hand on chest. Stethoscope is an instrument used by doctors to amplify these heart sounds.