1. All living things with a blood circulation system have blood pressure, which varies considerably at different times. In healthy people, blood pressure varies throughout the day and depends on factors such as physical activity and stress. There is a lot of difference between the blood pressure levels of children and of older people. Blood pressure rises considerably under stress situations. Environmental stress, food habits, lack of exercise and in general city life, are making a deep impact on human life, and as a result, for many, a rise in blood pressure is inevitable. In people who have high blood pressure, the heart always pumps with greater force than necessary, and blood pressure is never within the normal range.
2. In every drop of blood there are 250 million red blood cells. There are about 5 million red blood cells in each cubic millimeter of blood in the average adult man and 4.4 million per cubic millimeter in the average adult woman. There are far fewer white blood cells than red blood cells. In the blood stream there is only one white cell for approximately 700 red cells. There are normally about 8,000 white corpuscles in every cubic millimeter of blood. There are two main varieties: polymorphs and lymphocytes. Lymphocytes have a large nucleus that fills most of the cell. There are two types of lymphocytes, both of which originate before birth in bone marrow. Only mature lymphocytes carry out immune responses. During maturation process many different types of B and T lymphocytes develop, perhaps many millions.
3. The liver is a solid organ of dark-brown colour and the largest gland in the human body. It occupies the right-hand upper position of the abdominal cavity. About fourfifths of the organ lies to the right of the middle line of the body. The liver rests upon various abdominal organs, the right kidney and suprarenal gland, the large intestine, the duodenum, and the stomach. Liver tissue consists of thousands of tiny lobules. The liver has many functions vital to the body. Of the liver's many digestive functions the production of bile and storage of glucose are particularly important. The bile not only performs important functions in the process of digestion, but also serves as a vehicle for the excretion of waste products from the body. The liver has a double blood supply. The portal vein brings venous blood from the stomach, the intestines, and the spleen. The hepatic artery brings arterial blood. These two bring about 40 ounces (1,200 milliliters) of blood to the liver every minute.