The transport system of human beings is also called the circulatory system. It consists of
Blood vascular system and
The Blood Vascular System has three components
It is a muscular organ that plays the role of a pump in the circulatory system.
It pumps the blood to be circulated and also receives the blood from different body parts.
Blood is a fluid connective tissue. It is red because it contains red pigment called hemoglobin in its red cells.
The main function of blood is to supply nutrients and oxygen to all living cells and collect waste products and carbon dioxide to be thrown out of the body.
Blood consists of two main components
Plasma is straw colored fluid of the blood. It constitutes about 55% of blood volume. It is made up of water and various substances like proteins, salts, glucose, nitrogenous compounds etc.
The main function of plasma is to transport food, carbon dioxide, nitrogenous waste and hormones etc in dissolved form.
It constitutes about 45% of the blood. This includes
Red blood corpuscles (RBC)
It transports oxygen to all cells.
White blood corpuscles (WBC)–
It helps to destroy foreign particles and germs in the body.
Helps in blood clotting at the site of injury.
3. Blood vessels-
The tubes through which the blood flows are called blood vessels. The carry blood to and fro from different parts of the body. These are of three main types
They have thick muscular and elastic walls to which stand the high pressure of the blood emerging from the heart. Do not have valves.
They carry oxygenated blood from the heart to various organs of the body except pulmonary arteries.
They have thinner walls than the arteries and carry blood at low pressure. They have valves to prevent the backflow of blood.
Collect deoxygenated blood from different organs of the body and bring it back to the heart except pulmonary vein.
Artery device into smaller vessels known as capillaries. The walls of capillaries are one cell thick. They also have valves to prevent the backflow of blood.
They help in exchange of material between blood and surrounding cells that takes place across the thin walls of capillaries.
It is formed when some amount of plasma protein and blood cells escape from intercellular spaces in the tissues through the poles present in the walls of capillaries. It is similar to plasma but it is colorless with less proteins.
It carries digested and absorbed fats from intestine and drains back excess fluid to blood.
It maintains the balance between tissue fluid and blood.
Lymph nodes reduce WBC that prevent infection.