e the nerve which carry oxygenated blood from heart to various parts of body.ARTERIES are the nerve which carry oxygenated blood from heart to various parts of body.(2) Name the thinnest VESSEL which carry blood to individual cells.Capillaries are the thinnest vessel which carry blood to individual cells. (3) In a healthy person, what is the normal pulse rate.The normal pulse rate in a healthy person is 72 to 80 beats per minute. (4) Name the SCIENTIST who discovered blood groups.Karl Landsteiner discovered blood groups.(5) In how MANY groups human blood is categorised?There are 4 types of blood in Humans. --------------------------------------Arteries : Arteries carry oxygenated blood from the heart to all parts of body. Since, the blood flow is rapid and at a high pressure the arteries have thick elastic WALLS. Capillaries :On reaching the tissues, they are further divided into extremely thin tubes called Capillaries. Pulse :The throbbing movement in our hands is called Pulse. It is due to the blood flowing in the arteries. Karl Landsteiner :He was an Austrian scientist who discovered the ABO blood group system. He discovered in the year 1900. Blood Groups :There are 4 types of blood group which are A, B , O and AB.