Final answer:
Sagging and wrinkling of the integument occurs primarily due to a decrease in the elastic fiber network in the skin, which reduces the skin's elasticity and resilience.
Step-by-step explanation:
Sagging and wrinkling of the integument, or skin, occurs due to several age-related changes within the skin's structure. One of the key factors is the breakdown of the skin's structure, which includes a decrease in the production of collagen and elastin in the dermis. The skin also becomes thinner and loses its elasticity because elastic fibers and collagen fibers diminish over time.
Among the choices provided in the question, the most accurate answer would be a decrease in the elastic fiber network. This leads to a reduction in the skin's resilience and elasticity, contributing to both sagging and the development of wrinkles. Aging impacts the integumentary system by slowing down cell division, reducing metabolic activity, and causing a decrease in the regenerative abilities of the skin's different layers.