Mechanisms of food allergy

Allergy causes a vast range of illness. A food allergy is triggered when natural substance is mistaken for a hostile invader, causing immune systems to mobilize to repel the invader.

Allergic reactions may be IgE or non-IgE mediated or may include both types of mechanisms. Food allergies are mediated by IgE antibodies to protein-a characteristic shared with other allergens such as those present in hay fever (an acute allergic nasal condition) an wasp-sting reactions.

The immediate phase is the activation of mast cells and basophils and the release of mediators such as histamine, proteases, leukotrienes and cytokines. The IgE mediated type I reaction is involved in the pathogenesis of many cases of asthma, rhinitis, urticaria and atopic eczema as well as GI adverse reactions to food.

Non-IgE mediated reactions include contact dermatitis, food-protein-induced enteropathy and celiac disease, whereas examples of mixed type reactions are atopic dermatitis, gastroenteritis and asthma.

Allergy mostly affects the body’s interface with the environment – skin, conjunctivitis, airways and gut – but any organ can be affected when the reaction involves the microvasculature.
Mechanisms of food allergy 

Deglutition process

Deglutition process refers to process of swallowing. The process of deglutition can be viewed as comprising two stages, the formation and transfer of a food bolus across the pharynx and is passage from the laryngopharynx into the esophagus via the upper esophageal sphincter.

The food passes from the mouth into the pharynx. By the act of mastication, the food is softened and lubricated and the food bolus is placed over the dorsal surface of the tongue.

During of process of deglutition, the tongue pushes a bolus of food into the throat.

The nasopharynx is reflexively blocked. Respiration is inhibited, the vocal chords close and the epiglottis seals off the trachea, while the upper esophageal sphincter opens. The swallowing mechanism is coordinated in such a way that the food enters only down into the esophagus but not into other outlets.

A peristaltic wave forces the bolus into the stomach. Of the bolus gets stuck, stretching of the affected area triggers a secondary peristaltic wave.

Deglutition process occurs about 600 times during the day, during eating and drinking about 200-250 times, at other time 350 and during sleeping about 20 times.
Deglutition process

Roles of calcium in blood clotting

When blood vessels rupture, the process of blood coagulation is quickly activated. Blood coagulation is adaptive response to hemorrhage involving local conversion of liquid blood to a gel, which plugs a wound.

Calcium participates in nearly every steps of the blood clotting cascade. Calcium is essential for the formation of fibrin, the fibrous protein that makes up structure of blood clots.

According to Best and Taylor’s theory, when the blood is shed from wound, thromboplastin is liberated from the damaged tissue and disintegrated platelets.

It acts on prothrombin in the present of calcium and converts it to active thrombin. Prothrombin is produced in the liver and is present in small quantities in the blood plasma. Calcium occurs as an inorganic constituent in the plasma.

Now thrombin reacts with fibrinogen and converts it into fibrin, which is insoluble. Fibrin constitutes the blood clot in which the blood corpuscles are trapped.

Blood will not clot in the absence of calcium but calcium levels in the body seldom fall low enough to significantly impair blood clotting.
Roles of calcium in blood clotting