Final answer:
Calcium is lost through urinary excretion, fecal excretion via bile and digestive secretions, and through sweat, which is regulated by hormonal balance.
Step-by-step explanation:
Calcium is constantly being lost from the body in several forms, primarily through excretion. Major pathways for calcium loss include:
- a. urinary excretion of calcium by the kidneys
- b. excretion of calcium in the bile and digestive secretions, resulting in fecal calcium
- c. sweat, especially during vigorous physical exercise
Calcium homeostasis is a critical process, maintained through a balance of dietary intake, and regulated by hormones such as PTH (parathyroid hormone), vitamin D, and calcitonin. This balance becomes more challenging with age, especially during and after menopause, resulting in conditions such as osteoporosis.