Science 8 The Digestive System PDF

THE HUMAN DIGESTIVE SYSTEM What organs are included in the digestive system? I can statements:  I can describe the digestive process and the coordinated functions of the organs of the digestive system  I can trace the pathway of food from start to end. Digestive System Syst...

THE HUMAN DIGESTIVE SYSTEM What organs are included in the digestive system? I can statements:  I can describe the digestive process and the coordinated functions of the organs of the digestive system  I can trace the pathway of food from start to end. Digestive System System of the body that breaks down food into smaller parts that the body can absorb and use for energy, growth, and cell repair. Functions of the Digestive System 01 DIGESTION - is the breakdown of large insoluble food molecules into small water- soluble food molecules so that they can be absorbed into the watery blood plasma Two Types of Digestion 01 Mechanical Digestion (Physical) - begins in your mouth with chewing, then moves to churning in the stomach and segmentation in the small intestine. 01 Mechanical Digestion (Physical) Examples: Chew, tear, grind, mash and mix 02 Chemical Digestion -involves the secretions of enzymes throughout your digestive tract. -These enzymes break the chemical bonds that hold food particles together. -This allows food to be broken down into small, digestible parts. Major Processes of Digestion 01 INGESTION -refers to the entry of food into the alimentary canal through the mouth. - There, the food is chewed and mixed with saliva, which contains enzymes that begin breaking down the carbohydrates in the food plus some lipid digestion via lingual lipase. -Chewing increases the surface area of the food and allows an appropriately sized bolus to be produced. 02 ABSORPTION - refers to the movement of nutrients, water and electrolytes from the lumen of the small intestine into the cell, then into the blood. 02 ABSORPTION -They pass through the wall of the small intestine and into our bloodstream -Once there, the digested food molecules are carried around the body to where they are needed. -Only small, soluble substances can pass across the wall of the small intestine. Large insoluble substances cannot pass through. 03 ASSIMILATION -the process of absorbing nutrients during digestion and distributing them to the body for growth and repair. 04 ELIMINATION - Food molecules that cannot be digested or absorbed need to be eliminated from the body. -This is stored in the rectum, the lower part of the large intestine, until we are ready to go to the toilet. It then comes out of the rectum through the anus as feces. Why are bacteria important in the digestive system? - can digest some substances that humans cannot digest, such as certain carbohydrates reduce the chance of harmful bacteria multiplying and causing disease produce some vitamins that humans need, such as vitamins B and K PARTS AND FUNCTIONS OF DIGESTIVE ORGANS Digestive System Organization Gastrointestinal (Gl) tract ○ Tube within a tube ○ Direct link/path between organs ○ Structures Mouth Pharynx Esophagus Stomach Small intestine Large Intestine Rectum Mouth Epiglottis is a flap-like Teeth mechanically break structure at the back of down food into small pieces. the throat that closes Tongue mixes food with over the trachea saliva (contains amylase, preventing food from which helps break down entering it. starch). Esophagus Approximately 10” long Functions include: 1. Secrete mucus 2. Moves food from the throat to the stomach using muscle movement called peristalsis If acid from the stomach gets in here that’s heartburn. Stomach J-shaped muscular bag that stores the food you eat, breaks it down into tiny pieces. Mixes food with digestive juices that contain enzymes to break down proteins and lipids. Acid in the stomach kills bacteria. Food found in the stomach is called chyme. It can hold 1-1.5 liters of food Small Intestine Small intestines are roughly 7 meters long Lining of intestine walls has finger-like projections called villi, to increase surface area. The villi are covered in microvilli which further increases surface area for absorption. Duodenum (digestion and acid neutralization) Jejunum and ileum (absorption) Small Intestine Nutrients from the food pass into the bloodstream through the small intestine walls. Absorbs:  80% ingested water Vitamins  Minerals  Carbohydrates  Proteins  Lipids  Secretes digestive enzymes Large Intestine About 5 feet long Accepts what small intestines don’t absorb Rectum (short term storage which holds feces before it is expelled). Large Intestine – Absorbs more water – Concentrate wastes Functions Bacterial digestion Ferment carbohydrates Protein breakdown  Accessory Organs Not part of the path of food, but play a critical role. Include: Liver, gall bladder, and pancreas  Liver Directly affects digestion by producing bile Bile helps digest fat filters out toxins and waste including drugs and alcohol Gall Bladder Stores bile from the liver, releases it into the small intestine. Fatty diets can cause gallstones Pancreas Produces digestive enzymes to digest fats, carbohydrates and proteins Regulates blood sugar by producing insulin