Overview of Digestion and Nutrient Absorption.pdf

🍴 9/9/24, 8:00 PM Overview of Digestion and Nutrient Absorption Digestion Definition of Digestion Digestion is the breakdown of food into small pieces prior to absorption. Types of Digestion Int...

🍴 9/9/24, 8:00 PM Overview of Digestion and Nutrient Absorption Digestion Definition of Digestion Digestion is the breakdown of food into small pieces prior to absorption. Types of Digestion Intracellular Digestion: occurs within a single cell Extracellular Digestion: occurs outside of individual cells, utilizing tissues, organs, and muscles to digest food Human Digestive System Mouth: mechanical and chemical digestion begin Pharynx: a cavity common to both the digestive and respiratory systems Esophagus: a muscular tube responsible for guiding food to the stomach Mechanical and Chemical Digestion in the Mouth Mechanical Digestion: occurs via chewing in the mouth Chemical Digestion: occurs via salivary amylase in the mouth, targeting carbohydrates (starch breakdown into maltose) The Stomach 🍴 Mechanical and Chemical Digestion in the Stomach Mechanical Digestion: occurs via churning of smooth muscle regions in the stomach Chemical Digestion: occurs via digestive enzymes and highly acidic gastric juices The Sphincters Sphincter Location Function Cardiac Sphincter between esophagus and stomach prevents backflow of food and gastric juices into the esophagus Pyloric Sphincter between stomach and small intestine regulates deposits into the duodenum Cells of the Gastric Pits Mucous Cells: generate mucus that lubricates the stomach lining and protects it from low pH acids G Cells: release the hormone gastrin in response to a distended stomach Parietal Cells: release highly acidic gastric juice (hydrochloric acid, pH 2) Chief Cells: release gastric lipase and pepsinogen Small Intestine 🌮 Parts of the Small Intestine Duodenum: digestion occurs Jejunum: absorption occurs Ileum: absorption occurs https://www.turbolearn.ai/content/70d5d910-2d01-4589-a809-61b98c477847 1/4 9/9/24, 8:00 PM Overview of Digestion and Nutrient Absorption Goblet Cells Goblet cells secrete mucous that protects the small intestine epithelium from acidic chyme. Responses to Chyme Entering the Duodenum Small Intestine: releases Cholecystokinin (CCK) in response to chyme entering the duodenum Pancreas: releases digestive enzyme zymogens and bicarbonate ions in response to chyme Liver: generates bile and the gallbladder releases it into the duodenum in response to chyme Absorption Villi: finger-like projections of the enterocyte that increase surface area for absorption Microvilli: projections on the villi that further increase surface area Blood Capillaries: responsible for absorption of glucose and amino acids Lacteals: small lymphatic vessels that take fat to the rest of the body, responsible for absorption of fatty acids and glycerols Liver and Large Intestine 🌟 Liver Functions Blood Maintenance: filters and detoxifies blood that comes to the liver from the digestive system Glucose Metabolism: glycogenesis, glycogenolysis, and gluconeogenesis Protein Metabolism: protein synthesis and urea synthesis Hormone Synthesis: produces hormones such as insulin and glucagon Detoxification: processes chemicals and drugs in the blood to detoxify the body Bile Production: produces bile for fat emulsification Large Intestine Main Functions: water absorption, electrolyte absorption, and storage of feces Structures: cecum, appendix, colon, rectum, and anus Bacteria and the Large Intestine The large intestine is home to a diverse community of bacteria, known as the microbiome, which plays a crucial role in our overall health and well-being.## Liver Function 🧬 The liver plays a crucial role in various bodily functions, including: Protein Metabolism: The liver is responsible for synthesizing plasma proteins from amino acids, creating albumin and blood clotting factors. Urea Synthesis: The liver converts ammonia, a byproduct of protein metabolism, into urea, a safer version for excretion. Large Intestine Function 🌿 The large intestine, also known as the colon, has several main functions: Water Absorption: The large intestine absorbs water from the remaining waste material. Mineral Absorption: The large intestine absorbs minerals, such as salt, from the remaining waste material. https://www.turbolearn.ai/content/70d5d910-2d01-4589-a809-61b98c477847 2/4 9/9/24, 8:00 PM Overview of Digestion and Nutrient Absorption Vitamin Production and Absorption: The large intestine produces and absorbs vitamins, particularly vitamins B and K, with the help of 🗺️ certain bacterial species. Structures of the Large Intestine Structure Description Cecum The initial structure of the large intestine, responsible for water and mineral absorption. Appendix A vestigial structure of the large intestine, which can become inflamed and cause appendicitis. Colon The main part of the large intestine, responsible for completing water absorption and feces hardening. It is divided into the ascending, transverse, and descending colons. Rectum The site of feces storage in the large intestine. Anus The site of feces expulsion from the large intestine. Structure-Function Relationships of the Large Intestine 🤝 The Cecum is the initial structure of the large intestine, where water and mineral absorption occur. The Appendix is a vestigial structure that can become inflamed and cause appendicitis. The Colon completes water absorption and feces hardening, and is divided into the ascending, transverse, and descending colons. The Rectum stores feces, and the Anus expels feces from the large intestine. Bacteria and the Large Intestine 🐟 Microbiome: The range of bacterial species that coexist in the human large intestine and aid digestion. The microbiome is composed of 99% obligate anaerobes. Helpful Functions: The microbiome produces vitamins B and K, metabolizes bile acid, and ferments fiber. Key Functions of the Liver and Large Intestine 📝 Function Description Liver Functions Protein synthesis, urea synthesis, storage, hormone synthesis, detoxification, glucose and fat metabolism Large Intestine Functions Water absorption, mineral absorption, vitamin production and absorption Review Outline 📚 1. Liver functions include protein synthesis, urea synthesis, storage, hormone synthesis, detoxification, glucose and fat metabolism. 2. The liver processes blood by filtration and detoxification. 3. The liver maintains glucose levels via three mechanisms: glycogenesis, glycogenolysis, and gluconeogenesis. 4. Protein metabolism occurs in the liver. 5. Large intestine functions include water absorption, mineral absorption, and vitamin production. 6. The cecum absorbs water and minerals. 7. The appendix is a vestigial structure of the large intestine. 8. The colon completes water absorption. https://www.turbolearn.ai/content/70d5d910-2d01-4589-a809-61b98c477847 3/4 9/9/24, 8:00 PM Overview of Digestion and Nutrient Absorption 9. The rectum stores feces and the anus expels feces. 10. Coexisting intestinal bacteria make up the microbiome. 11. The microbiome is responsible for vitamin production, bile acid metabolism, and fiber fermentation. https://www.turbolearn.ai/content/70d5d910-2d01-4589-a809-61b98c477847 4/4