calcium metabolism vasudevan. .pptx

For 1st year mbbs students

1. CALCIUM INIYAN V L 1 st YEAR MBBS

2. OBJECTIVES INTRODUCTION SOURCES OF CALCIUM RDA ABSORPTION OF CALCIUM BIOCHEMICAL FUNCTIONS REGULATION APPLIED ASPECTS

3. INTRODUCTION Calcium is the important macrominerals which involved in various biological functions Total calcium in the human body is about 1 to 1.5 kg . 99% - bone and teeth 1% - ECF

4. SOURCES OF CALCIUM

5. RDA Adults- 1000mg per day Children- 750mg per day Pregnancy , Lactation , menopause – 1500mg per day

6. ABSORPTION Absorption is taking place from the first and second part of duodenum Absorption of calcium requires a carrier protein ( Calbindin) It is helped by calcium-dependent ATPase.

7. FACTORS AFFECTING CALCIUM ABSOPRTION FACTORS CAUSING INCREASED ABSORPTION VITAMIN D: Calcitriol induces synthesis of carrier protein PTH: Increases calcium transport from intestinal cell Amino acids : lysine and arginine increases Ca absorption Other factors like low pH , lactose. FACTORS CAUSING DECREASED ABSOPRTION OXALATES: Insoluble calcium oxalates formation reduces absorption. Phosphates: Optimum Ca to P ratio- 1:2 to 2:1 Fatty acids: formation of insoluble calcium salt of fatty acid. Other factors like high pH , phytic acid.

8. BIOCHEMICAL FUNCTIONS Mnemonics : BCCI MENS HAVE HEART

9. CALCIUM IN BLOOD Normal blood level: 9–11 mg/dL.

10. HOMEOSTASIS OF BLOOD CALCIUM LEVEL VITAMIN D:

11. PARATHYROID HARMONE It is synthesized as prepro -PTH with 115 amino acids. Prepro -PTH is broken to form the mature PTH with 84 amino acids. The first 35 amino acids of PTH are biologically active. PTH binds with specific receptor called CaSR

12. MECHANISM OF PTH

13. CALCITONIN

14. HYPERCALCEMIA The plasma calcium level is more than 11 mg/dL Major cause Hyperparathyroidism Calcium may be precipitated in urine leads to form calculi. OTHER CAUSES; PTH tumor Multiple myeloma Metastatic carcinoma of bone Dehydration Pagets disease

15. PAGET’S DISEASE Paget’s disease, also known as osteitis reformans It is a chronic bone disorder that typically affects older adults Characterized by excessive breakdown of bone tissue followed by abnormal bone formation SYMPTOMS: 1.Bone pain 2. deformities 3. increased risk of fractures

16. HYPOCALCEMIA The plasma calcium level is less than 9 mg/dL CASUSES : Rickets Hypoparathyroidism Medullary carcinoma of thyroid Osteoporesis Osteomegaly

17. TETANY If serum calcium level is less than 7.5 mg/dl CAUSES : 1.Accidental surgical removing of parathyroid gland 2. Autoimmune diseases MANIFESTATION: 1.Carpopedal spasm 2.Laryngismus and stridor(Laryngeal spasm lead to death) SYMPTOMS: 1.Chvostek’s and Trousseu’s sign are positive 2.Prolonged QT interval