Final answer:
Bone mass increases through mechanical stress, proper nutrition, and hormonal influences. It decreases due to factors like decreased physical activity, aging, and deficiencies in calcium and vitamin D, which impede bone formation and increase bone resorption.
Step-by-step explanation:
Bone mass can increase or decrease due to various factors. An increase in bone mass is typically stimulated by mechanical stress which leads to deposition of minerals and collagen fibers. Essential nutrients like calcium and vitamins, particularly vitamin D, play a crucial role in this process. Vitamin K, magnesium, and omega-3 fatty acids also support bone health. Hormones such as growth hormone, thyroxine, estrogen, and testosterone enhance mineralization and bone matrix formation.
On the other hand, bone mass can decrease due to decreased physical activity, which leads to a decline in the mechanical stress that is necessary for bone formation. The aging process can contribute to a natural increase in bone resorption over bone formation. Deficiencies in nutrients, such as calcium and vitamin D, result in inadequate bone formation and increased bone resorption. Poor absorption of nutrients, hyperparathyroidism, and diseases like osteoporosis are also important factors. Calcium absorption is heavily reliant on vitamin D, which when deficient, leads to weaker bones and potential bone diseases.