BSc Nursing 1 St Year Nutrition And Biochemistry Nursing Chapter 6 Vitamins Question And Answers

Vitamins

Question 1. Classification of vitamins.
Answer.

Vitamins may be regarded as organic compounds required in the diet in small amounts to perform specific biological functions for normal maintenance of optimum growth and health of the organism.

Although vitamins have little chemical similarities their metabolic functions have been described as

• Membrane stabilizers
• Hydrogen and electro donor & acceptor
• Hormones & coenzymes.

Classification of vitamins

Fat-soluble vitamins

• Vitamin A, D,E and K are know as fat or lipid – soluble vitamins.
• Their availability in the diet, absorption and transport are associated with fat.
• They are soluble in fats and oils and also the fat solvents (alcohol, acetone etc.)
• They are stored in the liver and adipose tissue.
• They are not readily excreted in urine. But with feceas via the enterohepatic circulation
• Excess consumption may lead to accumulation and toxic effects.

Water soluble vitamins

• Heterogeneous group of compounds since they differ chemically from each other.
• Common character – solubility in water.
• Readily excreted in urine and not toxic to body.
• Not stored in large quantities in the body (except vitamin B12).
• Stores depleted within weeks and deficiency symptoms results.
• Hence need to be continuously supplied through the diet.

Question 2. Functions of vitamin A
Answer.

• Fat soluble vitamin A (retinoids), refers to 3 preformed compounds
  • Alcohol – retinol
  • Aldehyde – retinal / retinaldehyde
  • Acid – retinoic acid
• Vitamin A is required for a variety of functions such as
  • Vision
  • Proper growth and differentiation
  • Reproduction
  • Maintenance of epithelial cells.
  • Vitamin A is required for normal reproduction
  • Vitamin A is required for epithelialization and is essential to maintain healthy epithelial tissue
  • Vitamin A is required for the construction of normal bone and teeth

Read And Learn More: BSc Nursing 1st Year Nutrition And Biochemistry Previous year Question and Answers

• • Vitamin A is required for glycoprotein synthesis
  • Vitamin A is required for the synthesis of chondroitin sulfate
  • Vitamin A plays a role in cell differentiation and cell division
  • Vitamin A is involved in protein synthesis
  • Vitamin A plays a role in DNA metabolism
  • Carotenes function as antioxidants and reduce the risk of cancers initiated by free radicals

Question 3. Deficiency manifestations of vitamin.
Answer.

Vitamin A Deficiency

• Retinol deficiency depresses the re-synthesis of rhodopsin and interferes with the function of rods resulting in night blindness
• In Vitamin A deficiency sperm cells do not mature and in females there may be abortion
• In Vitamin A deficiency the skin becomes dry, scaly and rough. These changes are called keratinization
• There is dryness of the conjunctiva and cornea, which is known as xerophthalmia
• White opaque spots, known as Bitots spots appear on the conjunctiva
• Cornea becomes keratinized, opaque, soft and ulcerated. This is known as keratomalacia
• Keratinization occurs in the mucous membrane of the respiratory tract leading to increased susceptibility to infection and lowered resistance to disease
• Vitamin A deficiency causes arrested bone development
• The teeth become unhealthy with chalky deposits on the surface

Question 4. Write the sources of vitamin A.
Answer.

Dietary Soruces

• Animal sources – liver, kidney, egg yolk, milk, cheese, butter and cod liver oil
• Vegetable sources – carotenes – carrots, spinach, pumpkins, mango and papaya
  • Foods provide vitamin A either in the preformed state (directly as retinol or retinyl esters of fatty acids ) from animal sources such as milk, butter, egg and fish.
  • Or its precursor carotenoids, especially carotene, derived from leafy vegetables and yellow and orange-coloured fruits and vegetables.

Question 5. Functions of vitamin C.
Answer.

Functions

• Vitamin C is required as a coenzyme in hydroxylation of proline and lysine Hydroxyproline and hydroxylysine are important constituents of collagen Thus vitamin C is required for collagen synthesis
• Vitamin C is required for bone formation
• Vitamin C enhances iron absorption by keeping it in the reduced ferrous
• Vitamin C is essential for the hydroxylation of tryptophan to hydroxy tryptophan in the synthesis of serotonin
• Vitamin C is required for the oxidation of P hydroxy phenyl pyruvate to homogentisic acid in tyrosine metabolism
• Vitamin C is required for the reduction of dihydrofolate (FH2) to tetrahydrofolate (FH4). Tetrahydrofolate (FH4) is the active form of folic acid
• Vitamin C is required for the synthesis of steroid hormones
• Vitamin C is a strong antioxidant. It spares vitamin A and vitamin E from oxidation
• Vitamin C enhances the synthesis of immunoglobulins
• Vitamin C increases the phagocytic activity of leucocytes
• Vitamin C is required for the formation of mucopolysaccharides
• Vitamin C is required for the functional activity of osteoblasts and fibroblasts
• Vitamin C is required for the formation of ferritin
• Vitamin C is required for the electron transport chain
• Vitamin C activates the enzyme arginase and inhibits the enzymes urease and amylase
• Vitamin C is required as a coenzyme for the conversion of dopamine to norepinephrine
• Vitamin C is required for the formation of carnitine
• Vitamin C is required for the alpha oxidation of fatty acids
• Vitamin C plays a role in reduction of blood cholesterol level
• Vitamin C plays an important role in the reaction of the body to stress

Question 6. Deficiency of vitamin C.
Answer.

Deficiency Of Vitamin C

• Vitamin C deficiency causes a disease called scurvy.
• The capillaries are fragile and there is a tendency to haemorrhage.
• The haemorrhage may be subcutaneous, subperiosteal or internal.
• Wound healing is deficient due to decreased formation of collagen.
• Poor teeth formation.
• Gums are swollen, spongy and bleed on slightest pressure.
• In severe infection there may be secondary infection, loosening and falling of teeth.
• Mineralization of the bone is poor and the bones are weak and easily fractured.
• Bones and joints are extremely painful.
• Hypochromic microcytic anemia.
• Elderly bachelors and widowers, who prepare their own food, are particularly prone to the development of vitamin C deficiency.
  This is called bachelor scurvy.

Question 7. Functions of vitamin D.
Answer.

• Calcitriol increases the intestinal absorption of calcium and phosphorus by increasing the synthesis of calcium binding protein. This protein increases calcium absorption by the intestine
• In the osteoblasts of the bone, calcitriol stimulates calcium uptake for deposition as calcium phosphate. Thus calcitriol is essential for bone formation
• Calcitriol increases the reabsorption of calcium and phosphorus by the kidney and thus decreases their excretion in the urine .

Question 8 . Deficiency manifestations of vitamin D.
Answer.

Deficiency Of Vitamin D

There are 3 types of vitamin D deficiency:

• Rickets
• Osteomalacia
• Renal osteodystrophy

Rickets

• Vitamin D deficiency in children is known as rickets
• In the absence of vitamin D the osteoblast proliferation is not accompanied by vascularization and mineralization at the normal rate
• The bones become soft
• Bending of long bones gives rise to deformities such as bow legs and knock knees
• The ankles, knees, wrists and elbows are swollen
• The fontanelles do not close properly giving rise to hot cross bun appearance of the head
• The ribs give a beaded appearance, known as ricket rosary
• The chest gives a pigeon breast appearance
• Teeth erupt late and are deformed

Osteomalacia

• Vitamin D deficiency in adults is known as osteomalacia
• Osteomalacia is seen in pregnancy and lactation, when there is additional requirement of vitamin D and drainage of it in the milk
• Osteomalacia is also seen in women who observe purdah and in areas where sunshine is scanty
• In osteomalacia the bones become soft and are easily fractured
• It particularly affects the pelvic bones

Renal Osteodystrophy

• It is also known as renal rickets
• It is seen in patients with chronic renal failure
• Renal rickets is mainly due to decreased synthesis of calcitriol by the kidney
• It can be treated by the administration of calcitriol

Question 8. List sources of thiamine (B1) and effect of its deficiency.
Answer.

Dietary Sources

• Plant sources – rice, wheat, peas, beans and nuts
• Animal sources – liver, meat, eggs, pork and milk

Deficiency Features

• The deficiency of thiamine results in a condition called beriberi (Sinhalese – I cannot, said twice)
• Cardiovascular features – these include palpitation, dyspnoea, cardiac hypertrophy, which may progress to congestive cardiac failure
• Neurological features
  • There is ascending, symmetrical, peripheral polyneuritis
  • Numbness in the legs
  • Pins and needles sensation in the legs
  • Mental depression and irritability
  • In some cases there may be acute hemorrhagic encephalitis, which is known as Wernicke’s encephalopathy
• GIT features
  These include decreased gastric motility, nausea, weakness, fever and vomiting.
• Metabolic features
  • There is accumulation of pentose sugars in the RBCs due to retardation of transketolation reaction
  • There is accumulation of pyruvate in the tissues and blood due to decreased activity of pyruvate dehydrogenase
• Types of beriberi
  It is of two types
  • Wet beriberi – in this oedema is present due to congestive cardiac failure and low plasma albumin level
  • Dry beriberi – oedema is absent.