Final answer:
The thyroid gland in the neck is responsible for controlling the body's metabolism, protein synthesis, and hormone sensitivity by releasing thyroid hormones, including T4 (thyroxine).
Step-by-step explanation:
The gland that controls how quickly the body burns energy (metabolism), makes proteins, and regulates the body’s sensitivity to hormones is the thyroid gland. A large endocrine gland located in the neck, the thyroid secretes hormones, including T4 (thyroxine) and T3, which play critical roles in maintaining cellular metabolism by increasing the rate at which cells use energy and produce proteins.
The endocrine system is integral to regulating metabolism, growth, and other functions, with various glands such as the thyroid, pituitary, and adrenal glands working in concert to release hormones that drive numerous bodily processes.