Calcium micronutrient, its importance to the human system, its sources, recommended dietary allowance, metabolism, functions and symptoms of deficiency.

1. UNIVERSITY OF BUEA REPUBLIC OF CAMEROON
PEACE – WORK – FATHERLAND
Coordinated
By
Prof. Achidi Aduni and Dr. Tiencheu Bernard
Senior Lecturers of Biochemistry and Molecular Biology, Faculty of Science
Presented
By
TEKE EFETI MARY
M.Sc. Biochemistry and Molecular Biology

2.  Introduction
 Sources of calcium
 Recommended dietary intake for calcium
 Metabolism of calcium
 Functions of calcium
 Calcium deficiency diseases/symptoms
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3.  Calcium is one of the body’s most abundant
electrolytes which are minerals that carry an electric
charge when dissolved in body fluids such as blood.
 But most of the blood calcium is uncharged
 About 99% of the body’s calcium is stored in the
bones, but cells(particularly muscle cells) and blood
also contains calcium.
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4.  Milk and Dairy products example yogurt, cheeses
 Egg yolk, Fish
 Beans
 Green leafy vegetables such as mustard greens, Chinese
cabbage
 Sardines and salmon canned with their soft bones
 Sunflower, dried beans
 Calcium is also found in many multivitamin-mineral
supplements example calcium citrate and calcium
carbonate
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5.  Adults – 500mg/day
 Children – 1200mg/day
 Pregnancy and lactation – 1500mg/day
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6.  This is the movement and regulation of calcium ions In
and out of the body and between body compartments:
the blood plasma, the extracellular and intracellular
fluids and bones
Absorption of calcium
 Calcium is first absorbed in the duodenum. Calcium
absorption against concentration gradient requires
energy and a carrier protein.
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8. Factors that decreases calcium absorption
 Phytate: specifically, phytate binds to Ca and
decreases its availability.
 Oxalates: it chelates Ca has a very low solubility and
increases fetal Ca excretion.
 High phosphate content: Calcium and phosphate react
in opposite ways
 Free fatty acids; calcium + FFA – insoluble calcium
soaps (steatorrhoea)
 Alkaline medium
 High dietary fiber: impairs the uptake of minerals
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9. Factors that increase absorption:
 Calcitriol: it acts on cells in the GIT to increase the
production of calcium transport proteins ( Calbidin-D
proteins) resulting in uptake of calcium from the gut
into the body
 Parathyroid hormone:
 Acidity
 Amino acids – lysine and arginine: increases calcium
absorption in situations like osteoporosis
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10.  Mineralization of bones and teeth: bone is a
mineralized connective tissue
 Coagulation of blood: calcium is factor 4 in
coagulation cascade. Prothrombin (factor 2) contains
Gla (gamma carboxy glutamate) residues.
 Calcium forms a bridge between Gla residues of
prothrombin and membrane phospholipids of platelets
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11.  Activation of enzymes: calmodulin is a calcium
binding regulatory protein. Calmodulin can bind with
4 calcium ions
 Nerves : calcium is necessary for transmission of nerve
impulses from pre-synaptic to post – synaptic region.
 Secretion of hormones: calcium mediates secretion of
insulin, parathyroid hormone, calcitonin, vasopressin,
etc from the cells
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12.  Secondary messenger signal transduction Calcium
and cyclic AMP are second messengers of different
hormones. One example is glucagon. Calcium is used
as second messenger in systems involving G proteins
and inositol triphosphate
 Myocardium: here, calcium promotes systole.
Caution: when calcium is administered intravenously, it
should be given very slowly to prevent cardiac arrest
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13.  The body deposits calcium in the bone when blood
levels get too high, and it releases calcium when blood
levels drop too low
 This process is regulated by PTH, vitamin D, and
calcitonin.
 Cells of the parathyroid gland have plasma membrane
receptors for calcium.
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14. Parathormone
 Secreted by chief cells of the four parathyroid gland.
Release of PTH is mediated by cAMP. It acts on;
kidney and intestine increasing serum calcium level
 When the calcium level in blood decreases, the
parathyroid glands produce more parathyroid hormone
and vice versa
 The PTH has the following effects
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15. In the bone, PTH directly
 induces pyrophosphatase
 Demineralisation or decalcification
 Solubilise calcium
 Causes bone resorption there by stimulating bone to
release calcium into blood
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16. In the Kidney, PTH directly
 Decreases renal excretion of calcium ( mainly by
increased reabsorption of calcium from distal tubules)
and increases phosphate excretion
 It stimulates the GIT to absorb more calcium
 It causes the kidney to activate vitamin D, which
enables the digestive tracts to absorb more calcium
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19. Calcitonin: is secreted by parafollicular cells of thyroid
gland
 It promotes calcification by increasing the activity of
osteoblasts
 Calcitonin decreases bone resorption
 It increases the excretion of calcium in urine
 Overall, it decreases blood calcium level
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21.  Toxicity: Hypercalcaemia
Symptoms: depression, confusion, irritability, anorexia,
abdominal pain, nausea, vomiting, cardiac arrhythmias
Causes
 Hyperparathyroidism: characterized by increased
serum calcium, decrease in serum phosphate and
increase in alkaline phosphatase activity
 Multiple myeloma ( Cancer of plasma cells)
 Pagets disease(one disease; skull, spine, legs, pelvis)
 Secondary bone cancer
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22.  Osteoporosis
 Kidney stone
 Kidney failure
 Nervous system problems
 Abnormal heart rhythm (arrhythmia)
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23. Calcium deficiency: Hypocalcemia
Symptoms: Neuromuscular irritability, spasms- laryngeal
spasm lead to death, convulsions, muscular cramps,
osteopenia(osteoporosis), dental problem, extreme fatigue, nail
and skin symptoms,
Causes
 Accidental surgical removal of parathyroid
 Renal disease
 Liver disease
 Vitamin D deficiency
 Osteoporosis: loss of bone calcium, making bone more
prone to fracture
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24. Rickets and Osteomalacia
 Rickets is a softening and weakening of bone
in children usually due to Vit D efficiency-
calcium absorption.
 Osteomalacia is marked softening of bones,
most often caused by severe vitamin D
deficiency
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25.  Sareen S Gropper, Jack L. Smith, James L. Groff:
Advanced Nutrition and Human Metabolism (fifth
edition)
 James L. Lewis: overview of calcium’s Role in the
body. MSD MANUAL consumer Version
 Alan L. Rubin: What are the functions of calcium in the
body?
 National institutes of Health ? US National Library o
Medicine; MedlinePlus: Calcium in Diet – calcium
2019.
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