Vitamin c
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Transcript of Vitamin c
VITAMIN C orASCORBIC ACID
• Functions• Clinical features & morphology of scurvy
Vitamin C
• Water soluble vitamin• 70 percentage of vitamin C is lost in the
process of cooking• Most animals & plants can synthesize ascorbic
acid from glucose• Man, higher primates, guineapigs & bats
cannot synthesize ascorbic acid
Dietary sources of vitamin C
• Amla ( Indian gooseberry- 700 mg/100 g)• Guava, lime, lemon• Green leafy vegetables• Milk & • Animal products like liver & fish
Functions of vitamin C
1. It can change between ascorbic acid & dehydroascorbic acid• Most physiological properties of vitamin are
explained by this redox system
2 . Ascorbic acid is necessary for the post transilational hydroxylation of proline & lysine residuesl Hydroxy proline & hydroxy lysine form cross
links in collagen- gives tensile strength to fibersl This process is necessary for the normal
production of supporting tissues like osteoid, collagen, and intercellular cement substances of capillaries
3 . Tryptophan metabolisml Hydroxylation of tryptophan to 5-hydroxy
tryptophan- formation of serotonin
4 . Tyrosine metabolisml Oxydation of parahydroxyphenylpyruvate to
homogenitisic acid
5 . Iron metabolisml Vit C reduces ferric iron to ferrous state, which
is preferentially absorbed from intestine
6 . Hemoglobin metabolisml Reconversion of met-hemoglobin to
hemoglobin
7 . Folic acid metabolisml Helps the enzyme folate reductase to reduce
foluc acid to tetrahydrofolic acidl Thus helps in maturation of RBC
8 . Steroid synthesisl Has some role in adrenal steroidogenesisl Vit C is present in adrenal cortex- depleted by
ACTH stimulation
9 . Stimulates phagocytic action of WBC
10 . Vit C is concentrated in the lens of eye Regular intake of vit C reduces risk of cataract formation
11 . Antioxidant propertyl Ability to scavenge free radicals directlyl Participate in metaboluc reactions that
regenerate antioxidant form of vit E
CLINICAL FEATURES & MORPHOLOGY OF
SCURVY
l Gross deficiency of vit C l Characterised by bone diseases in growing
children & by hemorrhages & healing defects in both children & adults
SYMPTOMS OF SCURVY
• Symptoms of scurvy generally develop after 3 months of severe or total vit C deficiency, they include;
l Wekness & fatiguel Bruising easily & bleeding from weakened blood
vessels, conn: tissue & bones due to collagen lossl Hair & teeth loss l Gingivitis: gums become painful, swollen & spongy
• Infantile scurvy (Barlow's disease): infants have pain when they move & lose their appetite.
• Infants do not gain weight as they normally do• In infants & children bone growth is impaired &
bleeding & anemia may occur• In infants between 6 to 12 months of age diet
should be supplemented with vitamin C sources
• Hemorrhagic tendency: collagen is abnormal & intercellular cement substance is brittle. So capillaries are fragile, bleed under minor pressure
• Subcutaneous hemorrhage manifested as petechiae in mild deficiency & as ecchymoses or hematoma in severe conditions
• In severe cases hemorrhage may occur in the conjunctiva & retina.
• In bones, deficiency results in failure of osteoblast to form the intercellular ground substance osteoid
• The resulting scorbutic bone is weak & fractures easily
• Hemorrhage into joint cavity lead to painful swelling of the joint
• Microcytic hypochromic anemia is seen• Poikilocytosis & anisocytosis are also common• Reason for anemia may be: • -loss of blood by hemorrhage• -decreased iron absorption• -decreased THFA
OBESITY
Obesity
• Pathogenesis• Metabolic changes
• Obesity is defined as a state of increased body weight, due to adipose tissue accumulation, that is of sufficient magnitude to produce adverse health effects
• One method to measure fat accumulation is to find the Body Mass Index(BMI)
• BMI- (wt in kg)/ (height in meters)2• Normal range- 18 to 25 kg/m2• 25-30-overweight, greater than 30 kg/m2-obesity
• Obesity results when-• -calorie intake exceeds utilisation• -lnactivity & sedentary lifestyle• -genetic predisposition• -diseases like hypothyroidism & cushing's
disease
PATHOGENESIS• Adipose mass is increased due to enlargement
of adipose cells due to excess lipid deposition & increase in number of adipocytes
• Excess consumption of nutrients
MORPHOLOGIC FEATURES
• Increased adipose stores in subcutaneous tissues, skeletal muscles & internal organs like kidneys, heart, liver & omentum
• Fatty liver is more common
MATABOLIC CHANGES
1 . Hyperinsulinemia Hyperglycemia due to a state of insulin resistance
2 . Type 2 DM Obesity exacerbate the diabetic state
3 . Hypertension Due to increased blood volume
4 . Hyperlipoproteinemia Normally plasma cholesterol circulates in blood as LDL Obesity associated with VLDL & mildly with LDL
5 . Atherosclerosis Risk of MI & stroke6 . Nonalcoholic fatty liver May progress to cirrhosis7 . Cholilithiasis8 . Hypoventilation syndrome (pickwickian syndrome)
9 . Osteoarthritis Due to wear & tear following trauma to joints10 . Cancer
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