Understand how your body is a bag of science

Hyderabad: This article is in continuation to the previous one focusing absorption of digested food products and disorders of digestive system.

• Fatty acids and glycerol, being insoluble, cannot be absorbed into the blood. They are first incorporated into small droplets called micelles which move into the intestinal mucosa. They are re-formed into very small protein coated fat globules called the chylomicrons which are transported into the lymph vessels (lacteals) in the villi. These lymph vessels ultimately release the absorbed substances into the blood stream.

• Absorption of substances takes place in different parts of the alimentary canal, like mouth, stomach, small intestine and large intestine. However, maximum absorption occurs in the small intestine.

• A summary of absorption (sites of absorption and substances absorbed) is given in Table.
Table content:

Mouth Stomach Small Intestine Large Intestine

Certain drugs coming in contact with the mucosa of mouth and lower side of the tongue are absorbed into the blood capillaries lining them. Absorption of water, simple sugars, and alcohol etc. takes place. Principal organ for absorption of nutrients. The digestion is completed here and the final products of digestion such as glucose, fructose, fatty acids, glycerol and amino acids are absorbed through the mucosa into the blood stream and lymph. Absorption of water, some minerals and drugs take place.

• The absorbed substances finally reach the tissues which utilise them for their activities. This process is called assimilation.

• The digestive wastes, solidified into coherent faeces in the rectum initiate a neural reflex causing an urge or desire for its removal.

• The egestion of faeces to the outside through the anal opening (defaecation) is a voluntary process and is carried out by a mass peristaltic movement.
Disorders of the digestive system

• The inflammation of the intestinal tract is the most common ailment due to bacterial or viral infections.

• The infections are also caused by the parasites of the intestine like tapeworm, roundworm, threadworm, hookworm, pin worm, etc.

Jaundice:

• The liver is affected, skin and eyes turn yellow due to the deposit of bile pigments.

Vomiting:

• It is the ejection of stomach contents through the mouth. This reflex action is controlled by the vomit centre in the medulla. A feeling of nausea precedes vomiting.

Diarrhoea:

• The abnormal frequency of bowel movement and increased liquidity of the faecal discharge is known as diarrhoea. It reduces the absorption of food.

Constipation:

• In constipation, the faeces are retained within the colon as the bowel movements occur irregularly.

Indigestion:

• In this condition, the food is not properly digested leading to a feeling of fullness. The causes of indigestion are inadequate enzyme secretion, anxiety, food poisoning, over eating, and spicy food.

Protein-Energy Malnutrition (PEM):

• PEM Dietary deficiencies of proteins and total food calories are widespread in many underdeveloped countries of south and south-east Asia, South America, and West and Central Africa.

• Protein-Energy Malnutrition (PEM) may affect large sections of the population during drought, famine and political turmoil.

• This happened in Bangladesh during the liberation war and in Ethiopia during a severe drought in mid-eighties.

• PEM affects infants and children to produce Marasmus and Kwashiorkar.