American Academy of Professional Coders (AAPC) Practice Exam

What physiological function occurs mostly in the hypodermis?

1. Formation of new skin layers

2. Storage of energy

3. Protection from pathogens

4. Production of melanin

The correct answer is: Storage of energy

The hypodermis, also known as the subcutaneous layer, serves several important roles within the body's structure, one of which is the storage of energy. This layer consists primarily of adipose tissue, which is a type of connective tissue that stores fat. The adipose tissue acts as an energy reserve for the body, providing insulation and cushioning for underlying structures such as muscles and organs. In addition to energy storage, the hypodermis aids in the absorption of shock and helps maintain body temperature by creating a barrier that reduces heat loss. This physiological function is crucial, as it allows the body to utilize stored energy during periods of calorie deficit or increased physical activity. The other listed functions—formation of new skin layers, protection from pathogens, and production of melanin—are associated with other layers of the skin, specifically the epidermis and dermis. The epidermis is primarily responsible for forming new skin layers, while the dermis contains immune cells that protect against pathogens. Melanin production occurs within specialized cells called melanocytes, which are located in the epidermis, not the hypodermis. Thus, the primary role of energy storage in the hypodermis distinguishes it as the correct answer.