Digestive System

Digestive System (Metabolism of food)

The conversion of food into energy is a process called metabolism.  There are two types of metabolism – anabolic, metabolism all the chemical changes that take place in the cells after the end products of digestion are absorbed. The Metabolism of food.  The nutritive value of food. The qualitative and quantitative requirements for food at different ages and developmental levels to meet physiological changes & activity needs. The changes in nutrient & food requirements that accompany or in the reduced risks of degenerative conditions &, The economic, psychological, social & cultural factors that affect the selection & eating of foods.

Look at following figure it shows you the essential parts of the digestive tract.

Metabolism of food

The liver and pancreas are not a part of the digestive tract but they secrete certain juices or secretions which do play a role in the process of digestion and absorption of food.

DIGESTION OF FOOD

Digestion takes place step-by-step at various sites in the digestive tract.

1. Mouth: - The process of digestion begins in the mouth where food is chewed by the teeth and mixed with saliva. While the food is still in the mouth, it is acted upon by and enzyme, amylase, which acts only on cooked carbohydrates and partially digests them or breaks them up into smaller units.
2. Stomach: - The chewed food mixed with Saliva the passes into the stomach through the tube-like structure called the oesophagus. It gets mixed with the digestive juice present in the stomach called gastric juice. Besides enzymes and water, gastric juice also contains small amounts of an acid called hydrochloric acid which makes it acid in nature. Mixing of food with the gastric juice converts the food into a thin soup-like consistency. Gastric juice contains and enzyme which acts on proteins and brings about their partial digestion.
3. Small intestine: - The partially digested mass of food passes from the stomach into the small intestine. The small intestine not only contains intestinal juice but also secretions from the liver and pancreas. The secretion from the liver is called bile and from the pancreas is known as pancreatic juice. Bile aids in the digestion and absorption of fats. Both pancreatic intestinal juices contain enzymes which break down fats, proteins and carbohydrates into simpler substances. These substances ultimately reach the bloodstream.
4. Large intestine: - The food which is not absorbed in the small intestine along with a large amount of water passes on to the large intestine. Here most of the excess water is reabsorbed and the remaining water and solid matter is eliminated from the body as faces.

ABSORPTION OF FOOD

Absorption takes place in the small intestine. The end products of digestion or the nutrients present in the small intestine can be used by the body only when they enter the bloodstream. This process of movement of digested food or nutrients across the intestinal wall to the bloodstream is termed absorption of food. The wall of the small intestine is made up of numerous folds or finger-like projections known as with.

UTILIZATION OF FOOD

Utilized for specific functions the absorbed end products or the nutrients from the food we eat further undergo chemical changes. They are broken down to release energy or are used to form complex substances. These substances can then be used to manufacture more complex or can be stored in the body.