HUMAN MEDICAL BIOLOGY, ANATOMY, PHYSIOLOGY AND PATHOLOGY - Y.I. Fedoniuk 2010

ANATOMY, PHYSIOLOGY, PATHOLOGY

CHAPTER 7. THE NUTRITIONAL PROCESS AND ITS PATHOLOGY

ANATOMY AND PHYSIOLOGY OF THE DIGESTIVE ORGANS

VITAMINS AND THEIR PHYSIOLOGICAL SIGNIFICANCE

Vitamins do not play a significant energetic or structural role; however, as essential components of enzyme molecules, they exert a profound influence on the physiological state of the body.

The primary source of vitamins is food products of PLANT AND ANIMAL origin, while some vitamins are synthesized by the intestinal microflora. Based on their solubility, vitamins are divided into two groups: Water-soluble (B-group vitamins, Vitamin C, Vitamin P) and fat-soluble (vitamins A, D, E, K).

A complete absence of vitamins in the diet leads to conditions known as avitaminoses. Insufficient vitamin intake causes hypovitaminosis, a condition with a milder clinical course than avitaminosis. Hypovitaminosis of a specific vitamin manifests with symptoms unique to that deficiency.

Avitaminoses and hypovitaminoses can also occur despite an adequate Dietary intake of vitamins if their absorption is impaired, particularly in gastrointestinal diseases.

The requirement for vitamins increases during periods of active growth in children, in pregnant women, in athletes undergoing intense physical training, and in patients undergoing prolonged antibiotic therapy.

Excessive intake of vitamins can lead to a pathological condition known hypervitaminosis, which can be just as dangerous as avitaminosis.

Vitamin C (ascorbic acid) participates in oxidation-reduction processes, strengthens vascular walls, enhances the detoxifying function of the Liver, and boosts the body's resistance to infections. The daily requirement for vitamin C is 50-100 mg. Vitamin C is abundant in lemons, bell peppers, cabbage, black currants, onions, rose hips, and potatoes, among other foods. Thermal Processing of food destroys vitamin C. Its deficiency leads to a disease known as scurvy, characterized by structural damage to Blood vessel walls, bleeding Gums, and hemorrhages.

Hypovitaminosis C is most commonly observed during the spring season.

Vitamin P (bioflavonoids). Treating scurvy with vitamin C alone does not yield a sufficient therapeutic effect; however, consuming natural juices leads to rapid recovery in patients. It has been discovered that fruits and vegetables contain vitamin P alongside ascorbic acid, and the absence of vitamin P in the diet also contributes to bleeding disorders.

Thus, scurvy develops not only due to a deficiency of dietary vitamin C, but also vitamin P. Working synergistically with vitamin C, vitamin P strengthens vascular walls and reduces capillary permeability. The daily requirement for vitamin P is 50 mg. It is found in black currants, rose hips, rowan berries, buckwheat, tea leaves, and cherries.

Vitamin B₁ (thiamine) plays a crucial role in carbohydrate, protein, and Lipid METABOLISM. It is involved in the conduction of nerve impulses and influences The activity of the Central Nervous system, particularly the Cerebral Cortex. Vitamin B₁ enhances the motor and secretory activity of the gastrointestinal tract. The daily requirement for an adult is 1.4-2.4 mg.

Vitamin B₁ is abundant in cereal grains, legumes, beef liver, and Heart. While it withstands mild thermal processing, exposure to temperatures of 120 °C leads to its complete destruction.

A deficiency of vitamin B₁ causes beriberi, manifested by motor disorders ranging up to paralysis, nerve damage, and dysfunctions of The Heart and gastrointestinal tract.

Vitamin B₂ (riboflavin) is a cellular component involved in cellular Respiration and affects the GROWTH AND DEVELOPMENT of both the fetus and the child. The daily dose of vitamin B₂ is 2-3 mg. It is rich in cereal grains, legumes, liver, heart, milk, eggs, spinach, and cauliflower. Riboflavin is destroyed by sunlight and in alkaline environments.

Hypovitaminosis B₂ leads to growth retardation and weight loss. A characteristic clinical picture emerges: transverse fissures on pale Lips, with crusts forming at the corners of the Mouth; the Tongue takes on a granular appearance with Teeth indentations along the edges. The facial Skin flushes, capillaries dilate, and Hair loses its color and falls out.

Vitamin B₆ (pyridoxine) is involved in Amino acid metabolism and synthesis, reduces Cholesterol accumulation in arterial walls, ensures proper iron utilization in the body, and influences hemopoiesis.

Although vitamin B₆ is synthesized by intestinal Bacteria in humans, an exogenous daily intake of 1.5-3 mg is still required.

Vitamin B₆ is found in liver, egg yolk, beef, legumes, cereal crops, and Yeast.

Avitaminosis B₆ leads to anemia and may cause Muscle cramps and spasms.

Vitamin B₁₂ (cyanocobalamin) is also known as Castle's extrinsic factor. This vitamin is absorbed after binding to a protein in gastric juice known as Castle's intrinsic factor. Disruption of this process leads to anemia and impairs The production of erythrocytes and platelets.

Rich sources of vitamin B₁₂ include animal liver (especially veal), fish liver, egg yolk, cheese, and milk. This vitamin is synthesized by the intestinal microflora. The daily requirement for vitamin B₁₂ is 2 mcg.

Vitamin PP (nicotinic acid) is involved in cellular respiration, normalizes the secretory and motor Functions of the gastrointestinal tract, and affects metabolism. Nicotinic acid enhances inhibitory processes in the cerebral cortex.

Nicotinic acid is abundant in bran, cereal and legume crops, animal liver, peanuts, and yeast.

Vitamin PP is stored in the body as a reserve, although this does not occur in liver diseases.

The daily requirement for nicotinic acid is 15 mg.

A deficiency of vitamin PP leads to a condition known as pellagra, characterized by dermatitis (skin inflammation), diarrhea, and dementia.

Vitamin A (retinol) has a specific impact on visual and reproductive functions. It ensures normal physical development and growth. Removing vitamin A from the diet inhibits animal growth. Adding a small amount of butter containing vitamin A to the diet restores growth. Retinol is involved in the synthesis of Hormones in the adrenal cortex and sex glands. Vitamin A deficiency can cause impaired Vision in dim light, known as night blindness. The lack of retinol can lead to damage to the Cytology/practical/76.html">Cornea of the eye: xerophthalmia (dry eye) and keratomalacia (clouding and formation of a corneal scar/spot).

Vitamin A is produced in the body from carotene, a yellow plant pigment. This process takes place in the liver. However, 1/3 of the daily requirement of vitamin A must be obtained by humans as preformed vitamin. The daily dose is 1.5 mg (5000 IU).

Vitamin A is found in animal fats (especially fish oil), butter, egg yolk, and milk. Carotene is abundant in yellow-colored vegetables and fruits: apricots, carrots, melons, and bananas.

Vitamin D (calciferols) regulates Calcium and phosphorus metabolism. This vitamin is essential for the normal development of a child.

A lack of vitamin D in early childhood causes Rickets. In such children, the Bone Formation process is disrupted due to a reduced content of calcium and phosphorus salts. Bones (especially the limbs) become soft and deform under the body's weight, taking on an O- or X-shape. Beads (rachitic rosary) appear on the Ribs, and the chest changes shape.

It has been proven that vitamin D is formed from an inactive substance, ergosterol, located in the skin, under The Influence of ultraviolet rays. This explains the positive effect of summer sunlight on children.

Sources of vitamin D include fish oil, cod liver, and egg yolks. Its daily dose is 2.5 mcg (100 IU).

Vitamin E (tocopherols) is involved in oxidation-reduction processes, Protein metabolism, strengthening vascular walls, and the biochemical processes of Muscle contraction.

This vitamin is widely distributed in nature. It is found in egg yolk, liver, wheat germ, unrefined vegetable oils, green leafy vegetables, bananas, and apples.

If vitamin E is absent from the diet, sexual function weakens and reproduction becomes impossible. Observations on rats have shown that although Fertilization and Pregnancy occur, the pregnancy is quickly interrupted and ends in Miscarriage.

The daily requirement for vitamin E is 12 mg.

Vitamin K (phylloquinones) promotes normal blood clotting. The daily dose of the vitamin is 0.3 mg. Spinach, lettuce, cabbage, tomatoes, and carrots are rich in vitamin K. Additionally, it is synthesized by the intestinal microflora.

Vitamin K deficiency leads to a reduced blood-clotting capacity. The Blood Coagulation process is impaired due to a decrease in blood prothrombin, which is synthesized in the body only in the presence of vitamin K.