Calcium homeostasis

calcium homeostasis by calcitonin, parathyroid hormone PTH.
Balance of calcium in human body

1. Hormonal Regulation Of Calcium Homeostasis Presented By: Adarsh Maurya MSc Previous Year Roll no: 05

2. Homeostasis If the system can not restore balance, It can lead to disease or death! H omeostasis is the state of steady internal, physical, and chemical conditions maintained by the body .  Challenges/Imbalance (Extrinsic/Intrinsic )

3. Function of Calcium Major structural element in the bones and teeth . Essential for several physiological processes such as neuromuscular transmission, muscle contractions, nerve function, cell division. Co-factor in Blood coagulation. Plays an important role in cell signaling . e.g. cAMP pathway Release of neurotransmitters and hormones.

4. Hormonal Regulation of Calcium H omeostasis

5. Role of Parathyroid Hormone (PTH) 84 amino acids residues. Secreted by the chief cells of 4 parathyroid glands. PTH increases serum calcium levels through: Increasing bone resorption by activating osteoclastic activity. Increasing renal calcium reabsorption by the distal renal tubules. Increasing the synthesis of Vitamin D in the kidney  Ca absorption from Intestine.

6. Role of Vitamin D (Calcitriol) Vitamin D  is a group of  fat-soluble   steroids  in humans, the most important compounds in this group are vitamin D 3  ( cholecalciferol ) and vitamin D 2  ( ergocalciferol ). Calcitriol's formation is facilitated by PTH. Vitamin D maintains calcium homeostasis by: Increasing calcium absorption from the intestine Stimulating calcium reabsorption from renal tubules. Vitamin D plays important roles in both bone absorption and bone deposition. At HIGHER level : promotes absorption of bone . At NORMAL level : promotes bone calcification .

7. Fig: Negative feedback loop (PTH and Vitamin D)

8. Role of Calcitonin 32 a.a. polypeptide secreted by the parafollicular cells in the thyroid gland . Major stimulus for calcitonin secretion is increased serum calcium .

9. Pathophysiology

10. Summary If this Homeostasis is disbalanced and can not be restored, various pathophysiological conditions arises. Ca++ level

11. References Hadley M.E., Levine L .E., Hormonal c ontrol of calcium and phosphate metabolism & physiology of bone (Page 369-376), Endocrinology, 6 th edition. Ganong W. F ., Hormonal c ontrol of calcium homeostasis (Page 189-210), Review of Medical Physiology, 23 rd edition. Guyton C., Hall E.J ., Parathyroid Hormone, Calcitonin, Calcium and Phosphate Metabolism, Vitamin D, Bone, and Teeth (Page 978-995), Textbook of Medical Physiology, 11 th edition. Kumar Pranav, Meena Usha, Endocrine System: Thyroid & Parathyroid glands (Page 453-454), Life Sciences (Part-II), 6 th edition . Internet Sources : Miscellaneous.

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