The anatomy, physiology, and functions of the endocrine system are reviewed. Age-related changes and specific disorders are grouped together to better understand their impact on the system and health of the older adults. Special attention is given to hyperthyroidism, hypothyroidism, and prediabetes and type 1 and type 2 diabetes. Recommended care for diabetics is also outlined.

The anatomy, physiology, and function of the immune system, lymphatic system, and lymph nodes are reviewed. Age-related changes of the immune system along with selected specific disorders that may be found in the older age group are discussed. HIV/AIDS in this population along with the cause, diagnosis, and treatment of the disease is defined.