Metabolism of Calcium , Phosphate , Vit D

4,421
-1

Published on

Published in: Health & Medicine, Technology
0 Comments
14 Likes
Statistics
Notes
  • Be the first to comment

No Downloads
Views
Total Views
4,421
On Slideshare
0
From Embeds
0
Number of Embeds
5
Actions
Shares
0
Downloads
535
Comments
0
Likes
14
Embeds 0
No embeds

No notes for slide

Metabolism of Calcium , Phosphate , Vit D

  1. 1. Metabolism of Calcium, Phosphate & Vit. D Parathyroid gland & Calcitonin DR. LAXMIKANTA SAY
  2. 2. CALCIUM METABOLISM
  3. 3. Distribution of Ca in ECF
  4. 4. FUNCTIONS OF CALCIUM 1. Calcium Homeostasis 2. Promotes Neuromuscular excitationcontraction coupling 3. Blood Coagulation 4. Membrane integrity & stabilization of cell Membrane 5. Release of Neurotransmitters from synaptic vesicles 6. Secretion from endocrine gland 7. Synthesis of Nucleic acids & proteins 8. Activation of enzymes
  5. 5. CALCIUM BALANCE Dietary requirements Adult Man Women, pregnant, lactation & post-menopause Children (1-18Yrs) Infants ( < 1Yr) 800 mg/day 1500 mg/day 800-1200 mg/day 300-500 mg/day Dietary Sources Milk & Milk products Beans, Leafy vegetables, Fish, Cabbage, Egg Yolk
  6. 6. PHOSPHOROUS METABOLISM
  7. 7. FUNCTIONS 1. Development of bone & teeth 2. Structural Part of : i. High energy transfer - ATP, GTP ii. Co-factors – NAD, NADP, TPP iii. Second Messenger – cAMP, inositol triphosphate iv. Nucleic acids (DNA & RNA) 3. Activation of enzymes by phosphorylation 4. Role in Carbohydrate metabolism 5.Phosphate buffer sysytem –pH regulation 6.Balances intracellular anions
  8. 8. PHOSPHOROUS BALANCE
  9. 9. CHOLESTEROL C A D B Vitamin D CHOLECALCIFEROL
  10. 10. SYNTHESIS
  11. 11. REGULATION OF SECRETION OF Vit. D
  12. 12. Other sites of Calcitriol synthesis    Placenta Keratinocytes Macrophages
  13. 13. Mechanism of Action
  14. 14. ACTIONS OF Vit. D Intestinal Ca absorption Intestinal phosphate absorption Renal excretion of Ca and phosphate Action on bone
  15. 15. Applied Aspect Rickets and Osteomalacia Vit. D resistance rickets Osteoporosis
  16. 16. Rickets Clinical Features A. Bone defect 1. Craniotabes 2. Widening of wrist 3. Collapse of Chest Wall 4. Rickety Rosary 5. Frontal bossing & posterior flattening of skull 6. Harrison’s Sulcus 7. Bowing of Legs or Knock-knee 8. Kyphosis & Pelvic deformities
  17. 17. B. General Features 1. Respiratory & G.I. infections 2. Developmental milestone Delay C. Tetany & Convulsions D. Biochemical Changes  Low plasma Calcium & Phosphate Serum alkaline phosphatase levels High Plasma Calcitriol low & absent Mangement Vit. D 25-125 µgm (1000-5000 IU)/day 6-8 wks
  18. 18. Osteomalacia Amount of mineral accretion in bone per unit of bone matrix is deficient Females - Multiple pregnancies, Lactation, Some time in Puberty Clinical Manifestation i. Long bone - soft, painful, deformed & terderness ii. Fractures occurs easily iii. Proximal Myopathy iv. S.Ca2+ low, S. inorganic phosphate low, S.alkaline phosphatase high
  19. 19. Osteoporosis Decrease in all constituents of Bone Decrease in bone mass with preservation of normal ratio of mineral to matrix Age >40yrs Postmenopausal women
  20. 20. Parathyroid Hormone
  21. 21. ANATOMY
  22. 22. SYNTHESIS
  23. 23. MECHANISM OF ACTION
  24. 24. Feedback Mechanism
  25. 25. ACTIONS 1. Effect on calcium & phosphate concentration in ECF 2. Absorption of calcium and phosphate from bone 3. Excretion of calcium and phosphate by kidney 4. Intestinal absorption of calcium and phosphate 5. Action on other ions
  26. 26. Applied Hypoparathyroidism Hyperparathyroidism Pseudohypoparathyroidism
  27. 27. Hypoparathyroidism Cause – Thyroidectomy Chvostek′ s sign Trousseau′s sign
  28. 28. HYPERPARATHYROIDISM
  29. 29. PTHrP 140 aminoacids Encoded by chromosome -12 Site of synthesis – uterus , enamel , brain , Keratinocytes , smooth muscle Action 1. Growth and development of cartilage in utero 2. Transport of Ca in placenta 3. Skeletal development 4. Inhibit excitatory damage to developing neuron
  30. 30. CALCITONIN Polypeptide with 32 aminoacid Secreted from Clear cells (C – Cells) or parafollicular cells of Thyroid gland Also known as Thyrocalcitonin Normal Secretion is 0.5 mg/day Half Life 15 min. MW – 3000 Normal Plasma Level – 0.2 ngm/ml
  31. 31. SECRETION Stimulators 1. Plasma Ca 2. β- adrenergic agonist 3. Dopamine 4. Estrogen 5. Gastrin 6. CCK – PZ 7. Glucagon 8. Secretin
  32. 32. ACTION Bone i. Inhibit osteoclastic activity ii. Inhibit active transport of Ca from bone to ECF iii. Increase alkaline phosphatase synthesis from osteoblast Kidney i. ii. iii. Synthesis of 1,25 DHCC Na+, Ca2+, Cl -, PO4 excretion Excretion of Hydroxyproline derived from bone
  33. 33. Cont.  GIT i. ii. Iii. Secretion of Water & Electrolyte Gastric Motility & Acid secretion Jejunal absorption of Ca2+ &Phosphate Physiological significance i. Active in Young individuals ii. Promote Ca2+ storage iii. Protection against Post prandial hypercalcemia iv. Protection of Mother during pregnancy
  34. 34. Calcium Homeostasis ↓ Plasma Ca ↑ PTH secretion from parathyroid gland ↑ Plasma PTH KIDNEY ↑ Ca reabsorption ↑ 1,25 DHCC ↓ Urinary excretion of Ca ↑ plasma 1, 25 DHCC Bone ↑ Resorption ↑ Release of Ca into plasma ↑ Ca absorption in intestine Restoration of plasma Ca towards normal
  35. 35. THANK YOU

×