Date post: | 06-May-2015 |
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MINERALS
Dr. Vijay Marakala, MBBS, MD.
Assistant professor BIOCHEMISTRY SIMS & RC
MINERALS
Minerals are inorganic compounds that are required for the body as one of the nutrients
MINERALS
Macrominerals Required in excess of
100mg/day
Ca++, P, S, Mg, Cl, Na, K.
Microminerals Required in amounts less than 100mg/day
Fe, Cu, Zn, Mo, I, Fl, Cr, CO, Mn
MINERALS
Calcium Phosphorous Iron Copper
Iodine Zinc Fluoride Magnesium
Manganese Selenium
MINERALS
CALCIUM O
BJEC
TIVE
S Sources and RDA
Metabolism of calcium
Functions of calcium
Regulation of plasma calcium
Disorders of calcium metabolism
CALCIUM
Calcium is the most abundant mineral in the body
Human body contain about 1-1.5 kg of calcium
SOURCES OF CALCIUM
DAILY REQUIREMENTS OF CALCIUM
Children 1000mg/day
Adults 500mg/day
Pregnancy and lactation1500mg/day
METABOLISM OF CALCIUM
Absorption Factors
affecting absorption
Mechanism of absorption
Excretion of calcium
Distribution and storage
METABOLISM OF CALCIUM - ABSORPTION
Site
Efficiency
Upper small
intestine
20-30% of dietary Ca
FACTORS AFFECTING CALCIUM ABSORPTION
Calcium absorption is increased by
CalcitriolPTHHigh protein dietOptimum Ca:P ratioAcidic pHBile salts
Absorption is decreased by
Alkaline pHPhytates and oxalatesSteatorrheaVitamin D deficiencyExcess phosphate in diet
MECHANISM OF CALCIUM
ABSORPTIONCalcium
absorption occurs by 1,25(OH)2D3
mediated mechanism.
EXCRETION OF CALCIUM
Stools Unabsorbed calcium in
the diet60 – 70%
Urine
50-200mg/day
Sweat
15mg/day
DISTRIBUTION AND STORAGE OF CALCIUM
Human body contain
about 1-1.5 kg of calcium
99% present in bone and teeth
1% in soft tissue and extracellular fluid
Plasma calcium : 9-11mg/100ml
FUNCTIONS OF CALCIUM
Formation of bone and teeth
Nerve conduction
Muscle contraction
Activation of enzymes
Blood coagulation Secretion of hormones
As a second messenger
Action on myocardium
REGULATION OF ENZYME ACTIVITY
Ca++ activates • Glycogen
phosphorylase kinase
• Amylase • PDH, IDH and α-
KGDH
Ca++ Inhibits • Pyruvate kinase• Trypsin
REGULATION OF PLASMA CALCIUM
50%40%
10%
%
Free or ionized calcium Protein boundcomplex with anions
REGULATION OF PLASMA CALCIUM
3 Organs
Gut
Bone
Kidney
3 Hormones
Calcitriol
PTH
Calcitonin
DISORDERS OF CALCIUM METABOLISM
HypocalcemiaHypercalcemia
HYPOCALCEMIA
Causes Features Treatment
HYPOCALCEMIA CAUSES Inadequate intake
Impaired absorption
Increased excretion
Magnesium deficiency
Acute pancreatitis
HYPOCALCEMIA - FEATURES Muscle cramps
and tetany
Laryngospasm
Convulsion
Cardiac arrhythmias
Prolongation of QT interval
Cataract
Chronic hypocalcemia
HYPOCALCEMIA – SIGNS OF TETANY
Contraction of facial muscle in response to tapping the facial nerve
Chvostek’s sign
Carpal spasm occurring after occlusion of the brachial artery with BP cuff for 3 min
Trousseau’s sign
HYPOCALCEMIA - TREATMENTSevere symptomatic
cases
Intravenous Calcium gluconate
Asymptomatic cases
Calcium carbonate
Vitamin D
HYPERCALCEMIA
Causes Features
Treatment
HYPERCALCEMIA CAUSES Increased intake
Increased absorption
Decreased excretion
Malignancy
HYPERCALCEMIA - FEATURESFEATURES Metastatic calcification
Neurological symptoms
Renal symptoms
Gastrointestinal symptoms
Cardiac arrhythmias
HYPERCALCEMIA - TREATMENT
Treatment of primary disease
Induction of natriuresis
Calcitonin