Digestion and Nutrition Lesson

Digestion and Nutrition Nutrition is about the way in which organisms obtain and use their food Physical digestion means physically breaking up the food into smaller particles this happens in mouth and stomach Chemical digestion This is where food is broken down i...

Digestion and Nutrition Nutrition is about the way in which organisms obtain and use their food Physical digestion means physically breaking up the food into smaller particles this happens in mouth and stomach Chemical digestion This is where food is broken down into a different substance that can easily pass into the blood 9/3/2024 1  STAGES OF NUTRITION Ingestion Digestion Absorption Egestion this is breakdown of when these removal of physically that food subunits pass that taking in the into more into the blood undigested food soluble and unabsorbed subunits. food material 9/3/2024 2  Digestive system The alimentary canal is a tube that runs from the mouth to the anus consists of a 25- to 30-foot-long muscular tube and organs such as the liver and pancreas that secrete digestive juices. o digestive juices - fluids that break foods down into their molecular components 9/3/2024 3  PROCESS OF DIGESTION Mouth The digestive process begins in the mouth. The food is broken down by the process of chewing and by the chemical action of salivary amylase amylase likes to work at a pH of approximately seven Saliva is excreted by three pairs of glands: - The parotid gland (below the ear) - The submandibular (under the tongue) - The sublingual (under the tongue) Esophagus The esophagus is a long tube that runs from the mouth to the stomach. It uses rhythmic, wave-like muscle movements (called peristalsis) to force food from the throat into the stomach. 9/3/2024 5  Stomach It is a J-shaped, elastic organ. It churns food with the gastric juices stomach produce gastric juice this contains hydrochloric acid and a protease an enzyme that breaks down proteins - hydrochloric acid lowers the pH of the stomach to around two and it kills bacteria - the low pH is essential for activating protease (enzyme that breaks down proteins). Because the protease is secreted in an inactive form called pepsinogen and it's only when it mixes with the hydrochloric acid that it's converted to the active form pepsin 9/3/2024 6 Small Intestine entering the small intestine is highly acidic and it's known as chyme - semifluid mixture consisting of a mixture of food and stomach secretions secretes enzymes that break down majority of carbohydrates, proteins, and fats site of the majority of nutrient absorption 9/3/2024 7 C O N T. D I G E S T I O N I N T H E S M A L L I N T E S T I N E Pancreas the pancreas it secretes many enzymes pancreatic enzymes (Ex. pancreatic amylase ,pancreatic proteases pancreatic lipase ) the pancreatic juice also contains sodium bicarbonate which is really important for neutralizing the acidic chyme. 9/3/2024 8 C O N T. D I G E S T I O N I N T H E S M A L L I N T E S T I N E Liver the liver is another important gland it produces bile Bile is secreted continuously by the liver and is concentrated and stored in the gallbladder. Bile is not an enzyme but an emulsifier that brings fats into suspension in water.After the fats are emulsified, enzymes can work on them 9/3/2024 9 9/3/2024 10 Cont. DIGESTION IN THE SMALL INTESTINE duodenum upper section of small intestine and it's here that most digestion takes place , this is because of the presence of these little finger-like projections known as villi 9/3/2024 11  Glands secrete intestinal juices - Important for neutralizing Chyme Villus Single Layer of Epithelial Cells Microvilli Protease and amylases secreted by the epithelial cell 9/3/2024 12 LARGE INTESTINE Undigested food passes in the large intestine. In the large intestine, some of the water and electrolytes (chemicals like sodium) are removed from the food Fiber also retains water, keeping the stools soft, and carries some bile acids, sterols, and fat out of the body 9/3/2024 13 9/3/2024 14 9/3/2024 15 9/3/2024 16