In our culture there is a diet related build up of cholesterol lining the walls of the arteries which limits or obstructs blood flow. In some cases the result may be elevated blood pressure. In other cases the function of particular organ may be affected by the impaired circulation. In extreme cases this condition can lead to heart attack or stroke. Physical conditioning and diet can modify some of the effects of aging to the cardiovascular system.
Blood consists of formed elements transported in a fluid called plasma.
Some of the formed elements include red blood cells, white blood cells, and platelets. Many other elements are found in the fluid, including vitamins, minerals, cholesterol, and the various byproducts of metabolism. Usually, any changes to the blood are related to disease rather than to aging. This lymphatic fluid travels through lymph nodes where bacteria and other foreign agents are filtered out and destroyed by the immune system. The thymus and spleen are responsible for producing the specialized cells for the immune system.