TRANSPORT IN HUMANS
- The main transport system in human beings (or man) is the ‘blood circulatory system
- The human blood circulatory system consists of the heart (the organ which pumps and receives the blood) and the blood vessels (or tubes) through which the blood flows in the body.
- In the blood circulatory system, the blood flows through three types of blood vessels : arteries, veins, and capillaries.
- In addition to the blood circulatory system for the transport in human beings, there is another system called the lymphatic system.
- The liquid which circulates and carries materials in the lymphatic system is called lymph.
- Thus, in human beings, the various substances are transported through two liquids called ‘blood’ and ‘lymph’
HUMAN CIRCULATORY SYSTEM
- The various organs of the circulatory system in humans are: Heart, Arteries, Veins and Capillaries.
- The arteries, veins and capillaries are a kind of thin pipes (or tubes) through which blood flows in the body.
- Arteries, veins and capillaries are called blood vessels.
- Arteries are the thick-walled blood vessels which carry blood from the heart to all the parts of the body.
- Arteries have thick walls because blood emerges from the heart under high pressure.
- The capillaries are thin walled and extremely narrow tubes or blood vessels which connect arteries to veins.
- The exchange of various materials like oxygen, food, carbon dioxide, etc., between the blood and the body cells takes place through capillaries.
- Veins are the thin walled blood vessels which carry blood from all the parts of the body back to the heart.
- Veins do not need thick walls because the blood flowing through them is no longer under high pressure.
Artery and Vain major difference
- The main difference between an artery and a vein is that an artery carries blood from the heart to the body organs whereas a vein carries blood from the body organs back to the heart