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Nutrition in Humans Homework Help

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The Role of Nutrition in Humans

The food that we eat is complex in nature and is hence broken down into simpler substances by our digestive system so that it can be utilized for various purposes. Thus, we derive energy for various internal and external body works such as repairing of cells, synthesis of new cells, playing, exercising, and walking.

Nutrition in Humans

Nutrition in humans takes place through a specialized system, known as the digestive system. The digestive system starts from the mouth and buccal cavity and ends in the anus. The digestive system is responsible for the breakdown of food and the supply of energy from the food to the cells of the body.

The Process of Digestive System in Human

The food that we eat through our mouth undergoes mechanical/physical treatment via the chewing process of our teeth.

The teeth are responsible for breaking down the food and the mouth mixes the food with saliva, secreted from the sebaceous glands.

The saliva contains specialized digestive enzymes like salivary amylase, which breaks down the complex starch present in the food into simple sugar molecules.

The food is passed down through the food pipe or esophagus.

The food then enters the stomach which constantly expands and contracts to aid the movement of digestion. This movement of the stomach is known as peristalsis.

The stomach contains muscular walls that aid in the mixing of food with digestive juices.

The stomach contains gastric glands which secrete hydrochloric acid. Hydrochloric acid creates an acidic pH, which helps in the activation of the pepsin enzyme.

Hydrochloric acid also assists in the breakdown of proteins into peptones.

The food is churned well in the stomach and only when food is partially digested, the stomach opens up to the small intestine through a small opening called the sphincter muscle.

The sphincter muscle releases the food to the small intestine in small amounts.

The food is passed down to the small intestine where it is completely digested. The small intestines are the largest organ of the digestive system and are coiled in a small space.

The small intestines receive digestive juices, bile from the liver, and glucagon and insulin from the pancreas. These digestive juices help to complete the digestion of the food.

The food received from the stomach in acidic conditions is converted to an alkaline condition by bile salts secreted from the liver.

Bile salts are primarily responsible for breaking down fats.

The pancreas produces insulin which regulates blood glucose levels.

The pancreas also produces pancreatic juice which consists of enzymes like pepsin, and trypsin which is responsible for breaking down the peptones into peptides, and lipase produced is responsible for breaking down fats into fatty acids.

In addition to this, the walls of the intestine also secrete intestinal juice, which finally converts the remaining proteins to amino acids, carbohydrates to simple sugars, and emulsified fats to fatty acids.

The wall of the intestine has an inner lining that consists of numerous finger-like projections called villus (plural – villi). These villi are surrounded by blood vessels.

The villi are responsible for expanding the surface area of the intestine so that the food is completely digested.

The simpler substances of the food in the intestine are then absorbed by the blood vessels are transported to various cells of the body, where the molecules are assembled to generate specialized proteins for varied repair mechanisms of the body, carbohydrates, and fats for energy utilization purposes.

The unabsorbed food is then passed on to the large intestine. In the large intestine, the excess water and nutrients are absorbed, and then the remaining wastes in passed to the anus via the rectum and colon.