Final answer:
The hypodermis, rich in adipose tissue, is primarily responsible for providing the body's smoothness and contour as well as a protective cushion. The dermis also adds cushioning and elasticity to the skin. Furthermore, the skin serves as a barrier, protecting against environmental damage and helping with homeostasis.
Step-by-step explanation:
The body's smoothness and contour are primarily provided by the hypodermis, which also gives a protective cushion for the skin. The hypodermis is the underlying layer beneath the dermis and it plays vital roles in storing fats, forming a cushion over underlying structures, and providing insulation from cold temperatures. This layer is rich in adipose tissue, which is responsible for the protective padding that helps cushion the body's internal organs against shocks and impacts, offering a layer of protection. The hypodermis also contributes to the body's contours and smoothness by providing a layer that fills the space between the skin and the underlying structures of the body, such as muscles and bones.
In addition to the hypodermis, the dermis itself assists in maintaining the smoothness and contour of the body. The dermis is a matrix composed of connective tissues including collagen fibers, which give toughness; and elastin fibers, which provide elasticity. The dense connective tissues of the dermis offer additional cushioning, while its elasticity helps the skin maintain its shape and firmness.
Moreover, the skin performs crucial protection functions for the body. It serves as a barrier against environmental factors, such as wind, water, UV sunlight, and invasion by microorganisms, thus preventing dehydration and infection. The production of sweat and sebum from glands within the skin also plays roles in protection and homeostasis by cooling the body and keeping the skin moisturized, respectively.