This video carries complete informaton about the production and effects of PTH and calcitonin hormones. It also explains the primary stimulation that is required to continue the pathway. timeline: 0:07 introduction 1:05 type of cells (parathyroid glands) 4:00 PTH release (low calcium) 7:00 calcitonin release (high calcium) 11:00 effects of PTH (mechanism) 28:50 effect of calcitonin (mechanism)