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Digestive System

Non-Surgical Non‐Surgical Procedure to Fight Obesity Intra‐gastric balloons ‐ This system uses an endoscope to implant a fluid‐filled balloon into the stomach. The saline‐filled balloon occupies about one third of the stomach cavity, decreasing the quantity of food that the stomach can hold and promoting diminished appetite. The procedure can be completed under sedation in a single office visit and is adjustable as desired. It is ideal for those who need to lose 22 pounds or more. Let's learn how our gastrointestinal system works and the disorders associated with it.

Learning Objectives

After completing the topic, the student will be able to:

  • Understand and explore the functional significance of gastrointestinal system in humans.
  • List all the major components of the human digestive tract, from the mouth to the anus.
  • Illustrate the structure of stomach and list the secretions of stomach which helps in digestion.
  • Compare and contrast the structural and functional features of the small intestine and large intestine.
  • Explore the water recovery mechanism that occurs in large intestine and systematize the sections of it.
  • Discuss the major functions of the pancreas, liver, and gallbladder which acts as digestive accessories.
  • Identify the major hormones, peptides and key neurotransmitters of the gastrointestinal system.
  • Summarize the overall characteristics and functions of digestive enzymes.
  • List some of the disorders associated with gastrointestinal system.
Distribution of the calories Carbohydrate, protein, and fats are determined partly by physiologic factors and partly by taste and economic considerations.
Nutrition

The aim of the science of nutrition is the determination of the kinds and amounts of foods that promote health and well-being. This includes not only the problems of undernutrition but those of overnutrition, taste, and availability. However, certain substances are essential constituents of any human diet. Many of these compounds have been mentioned in the previous sections, and a brief summary of the essential and desirable dietary components is presented below.

Essential dietary components: An optimal diet includes, in addition to sufficient water, adequate calories, protein, fat, minerals, and vitamins.

Caloric intake and distribution: The caloric value of the dietary intake must be approximately equal to the energy expended if body weight is to be maintained. In addition to the 2000 kcal/d necessary to meet basal needs, 500 to 2500 kcal/d (or more) are required to meet the energy demands of daily activities.

The distribution of the calories among carbohydrate, protein, and fat is determined partly by physiologic factors and partly by taste and economic considerations. A daily protein intake of 1 g/kg body weight to supply the eight nutritionally essential amino acids and other amino acids is desirable. The source of the protein is also important. Grade 1 proteins , the animal proteins of meat, fish, dairy products, and eggs, contain amino acids in approximately the proportions required for protein synthesis and other uses. Some of the plant proteins are also grade 1, but most are grade 2 because they supply different proportions of amino acid and some lack one or more of the essential amino acids.

Role of carbohydrates and fats in diet Carbohydrates are the body’s main source of fuel. Fat is the most concentrated source of energy
Significant factors of food

Fat is the most compact form of food, since it supplies 9.3 kcal/g. However, often it is also the most expensive. Indeed, internationally there is a reasonably good positive correlation between fat intake and standard of living. In the past, Western diets have contained large amounts (100 g/d or more). The evidence indicating that a high unsaturated/saturated fat ratio in the diet is of value in the prevention of atherosclerosis and the current interest in prevention obesity may change this. In Central and South America Indian communities where corn (carbohydrate) is the dietary staple, adults live without ill effects for years on a very low fat intake. Therefore, provided that the needs for essential fatty acids are met, a low-fat intake does not seem to be harmful, and a diet low in saturated fats in desirable.

Carbohydrate is the cheapest source of calories and provides 50% or more of the calories in most diets. In the average middle-class American diet, approximately 50% of the calories come from carbohydrate, 15% from protein, and 35% from fat. When calculating dietary needs, it is usual to meet the protein requirement first and then split the remaining calories between fat and carbohydrate, depending on taste, income, and other factors. For example, a 65-kg man who is moderately active needs about 2800 kcal/d. He should eat at least 65g of protein daily, supplying 267 (65 × 4.1) kcal. Some of this should be grade 1 protein. A reasonable figure for fat intake is 50 to 60 g. The rest of the caloric requirement can be met by supplying carbohydrate.

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