Final answer:
The declining efficiency of the immune system with age, known as immunosenescence, is caused by factors such as thymic involution, decreased production of antibodies, and communication and coordination issues within the immune system. Other factors that contribute to declining efficiency include malnutrition, certain medications, stress, and genetic disorders.
Step-by-step explanation:
The declining efficiency of the immune system with age is due to a process called immunosenescence. Immunosenescence is the natural age-related decline in immune function that begins around age 50 and worsens with increasing age. One major cause of this decline is thymic involution, which is the shrinking of the thymus gland that starts at birth. As the thymus shrinks, it produces fewer T cells, which are essential for immune response. Other factors that contribute to the declining efficiency of the immune system with age include decreased production of antibodies, reduced ability of immune cells to communicate and coordinate an immune response, and decreased ability of immune cells to clear pathogens efficiently.
In addition to immunosenescence, other factors can affect the efficiency of the immune system, such as malnutrition, certain medications, stress, and genetic disorders. Malnutrition, especially inadequate protein intake, can impair the function of immune cells and reduce the production of antibodies. Certain medications, like immunosuppressants, can suppress the immune system as a side effect and make individuals more susceptible to infections. Chronic stress can also weaken the immune system and make individuals more prone to illness. Finally, genetic disorders like Severe Combined Immunodeficiency (SCID) can result in a weakened immune system.