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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