Final answer:
The correct pathway for calcium absorption is Dietary Absorption, which occurs in the intestines with the help of activated vitamin D. It is a crucial process for maintaining calcium balance, regulated by blood calcium levels and hormones like PTH.
Step-by-step explanation:
The viable pathway for calcium absorption is A) Dietary Absorption. Calcium is absorbed through the intestines under the influence of activated vitamin D. When there is a deficiency of vitamin D, the absorption of calcium from the intestines decreases, which can lead to a depletion of calcium stores in the bones. This deficiency can result in conditions such as rickets in children and osteomalacia in adults.
Calcium absorption is a critical process that is influenced by blood levels of ionic calcium. When these blood levels drop, the hormone PTH (parathyroid hormone) is released, which stimulates the release of calcium ions from the bones and increases calcium reabsorption in the kidneys. PTH also upregulates the activation of vitamin D, which in turn enhances the absorption of calcium from the intestine to maintain normal calcium concentration.