Playlist: Digestion and Nutrition
This program examines the chemical structure of food and the human body’s ability to convert food into fuel and raw materials. Major and minor nutrients are defined, catabolism and anabolism are contrasted, and the function of the digestive tract at the cellular level is scrutinized. The sequence of physical and chemical processes that facilitate digestion is also illustrated, spotlighting each constituent anatomical system: mouth/esophagus, stomach, small intestine, and large intestine. A segment on healthier eating concludes the program. A viewable/printable instructor’s guide is available online. A Films for the Humanities & Sciences Production. A part of the series The Human Body: How It Works. (22 minutes)
Why do we get hungry? What happens to the food we eat? Why is it important to limit the intake of certain foods?
Nutrients from food must be changed into energy. Adenosine triphosphate (ATP) directly or indirectly delivers energy to almost all metabolic pathways. Major nutrients are carbohydrates, proteins, and lipids. Minor nutrients include vitamins and minerals.
Sugars and starches both provide energy when the molecules are broken down. Carbohydrates come in three sizes: monosaccharides, disaccharides, and polysaccharides.
Proteins are made of long chains of amino acids. Proteins are the main building blocks for cells and tissues. They provide strength to tendons and ligaments.
Fats are one of the three types of major nutrients. The kinds of lipids are phospholipids, triglycerides, and steroids.
Minor nutrients include vitamins and minerals. Vitamins are organic compounds; minerals are inorganic elements. ATP production involves glycolysis, the Krebs cycle, and electron transport chain.
The walls of the digestive tube are composed of four layers: mucosa, submucosa, muscularis, and serosa. The innermost mucosa is lined with absorptive columnar cells that absorb nutrients that are then distributed throughout the body.
Food enters the stomach through the cardiac sphincter. The stomach secretes digestive juices to dissolve the food, and then it passes the mixed food and acids (chyme) into the small intestine where nutrients are absorbed by the blood.