Imune System. Immune System
The aging of the immune system, known as immunosenescence, includes a depressed immune, response, which can cause infections to be a significant risk of older adults. After midlife, thymic mass decreases steadily to the point that serum activity of thymic hormones is almost undetectable in the aged. T-cell activity declines and more immature T cells are present in the thymus. A significant decline in cell-mediated immunity occurs, and T lymphocytes are less able to proliferate in response to mitogens Changes in the T cells contribute to the reactivation of varicella zoster and Mycobacterum tuberculosis, infections that are witnessed in many older individuals. Stress can affect the function of the immune system because elevated cortisol levels can lead to a break-
down in lymphoid tissue, inhibition of the producton of natural killer cells, increases in T-suppressor cells, and reductions in the levels of T-helper cells and virus-fighting interferon.
Cancer. The most frequently seen cancer types in population over 70 years are lung cancer, and prostate cancer in men, and breast cancer, and colorectal cancers in women. Cancer is a disease in which some of the body's cells grow uncontrollably and spread to other parts of the body. Cancer can start almost anywhere in the human body, which is made up of trillions of cells
Rheumatoid arthritis. your immune system mistakenly sends antibodies to the lining of your joints, where they attack the tissue surrounding the joint. This causes the thin layer of cells (synovium) covering your joints to become sore and inflamed, releasing chemicals that damage bones, cartilage, ligaments and tendons.