Pg.no. 12
Function:
The main function of the circulatory system is to deliver oxygen to the body tissues, whilst
simultaneously removing carbon dioxide produced by metabolism. Oxygen is bound to
molecules called hemoglobin that are on the surface of the red blood cells in the blood.
Beginning in the heart, deoxygenated blood (containing carbon dioxide) is returned from
systemic circulation to the right side of the heart. It is pumped into pulmonary circulation and is
delivered to the lungs, where gas exchange occurs. The carbon dioxide is removed from the
blood and replaced with oxygen. The blood is now oxygenated, and returns to the left side of the
heart. From there, it is pumped into the systemic circuit, delivers oxygen to the tissues, and
returns again to the right side of the heart. The blood also acts as an excellent transport medium
for nutrients, such as electrolytes, as well as hormones. The blood also transports waste products
that are filtered from the blood in the liver.
Blood
Blood is made up of plasma, blood cells, proteins and salts. Plasma is the fluid part of blood
which contains 90% of water. Blood cells are the solid part of the blood which is of three
types-
Red Blood Cells or RBCs are used for transporting food, oxygen and other
substances to other part of body along with removing waste.
White Blood Cells or WBCs are used for fighting against the foreign particles that
enter the body since they are specialized in defense.
Platelets are used for clotting in blood at the time of wound or cut to stop excess
flow of blood.
Blood Vessels
Blood vessels are the carrier of blood through which the blood travels to different parts of
the body. There are two types of blood vessels-
Arteries- These carry oxygenated (oxygen-rich) blood. These are thick, elastic and
carry the blood away from the heart. These are divided into small network of blood
vessels known as capillaries.
Veins- These carry deoxygenated (carbon dioxide-rich) blood. These are thin, elastic
and bring the blood towards the heart.
Heart
It’s a fist-size organ that is located near a chest but slightly towards left. This works non-stop
and pumps blood. If this stops beating, a person dies. There are four chambers of heart where
the mixing of oxygenated and deoxygenated blood takes place. The four chambers are
composed of two atria and two ventricles. Atria are upper chambers while the ventricles are
lower chambers.