1 / 47

Human Digestion and Absorption

Human Digestion and Absorption. Chapter 4. Mouth (Oral Cavity). Chewing increases surface area Mixed with saliva food becomes a bolus Saliva Lysozyme Breaks down bacteria Mucus Lubricates and hold bolus together Amylase Breaks down starch Enhances perception of flavor. Taste and Smell.

kaveri
Download Presentation

Human Digestion and Absorption

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Human Digestion and Absorption Chapter 4

  2. Mouth (Oral Cavity) • Chewing increases surface area • Mixed with saliva food becomes a bolus • Saliva • Lysozyme • Breaks down bacteria • Mucus • Lubricates and hold bolus together • Amylase • Breaks down starch • Enhances perception of flavor

  3. Taste and Smell • Taste buds – contain receptors • Salty • Sour • Sweet • Bitter • Umami • Olfactory cells in nose (smell) • Stimulated with chewing

  4. Stomach Secretions • Parietal Cells • Hydrochloric Acid • Inactivates proteins • Destroys bacteria and viruses • Dissolves minerals to aid in absorption • Converts pepsinogen into pepsin • Pepsinogen • Protein digesting enzyme • Gastrin • Hormone that controls release of HCl and pepsinogen

  5. Other Stomach Secretions • Chief cells • Gastric lipase • Mucus • Protects the stomach from being digested • Production relies on prostaglandins

  6. Small Intestine • Most digestion and absorption occurs here • Pyloric sphincter allows chyme into the small intestine • Gastric inhibitory peptide (hormone) slows release of chyme • Sections • Duodenum, jejunum and ileum

  7. Small Intestine (2) • Circular folds • Villi – lined with: • Goblet cells - make mucus • Endocrine cells - produce hormones • Enterocytes - produce digestive enzymes and absorb nutrients • Contain a brush border of microvilli covered with glycocalyx

  8. Liver, Gallbladder and Pancreas • Liver • Provides bile • Enterohepatic circulation (recycling of bile) • Gallbladder • Bile storage • Pancreas • Produces sodium bicarbonate, lipases, proteases and pancreatic amylase

  9. Gallstones are the most common cause of pancreatitis in the US and accounts for 35–50% of all cases. Despite aggressive and intensive early management, the mortality rate is approximately 10%. Obstruction of the major papilla by the stone causes reflux of bile into the pancreatic duct.

  10. Hormones of the GI Tract • Gastrin • Stomach release of HCl and pepsinogen • Cholescystokinin (CCK) • Release of bile • Secretin • Release of pancreatic bicarbonate • Gastric Inhibitory Peptide • Limits release of gastric juices

  11. Absorption • Primarily occurs in small intestine • Passive diffusion • Concentration gradient • Facilitated diffusion • Concentration gradient + carrier protein • Active • Carrier protein + energy (regardless of concentration) • Endocytosis • Engulfment of compounds or liquids

  12. Blood Water-soluble nutrients transported via capillaries in villi to portal vein to liver Lymphatic System Fat-soluble nutrients transported via lacteals into the lymph vessels to thoracic duct Moving Nutrients around the Body

  13. Large Intestine • Ileocecal valve • Colon • Cecum, ascending colon, transverse colon, descending colon and sigmoid colon • Rectum • Anus

  14. Functions of Large Intestine • Absorption of water and electrolytes • Formation and expulsion of feces • Housing of bacteria (microbiota)

  15. Microbiota (bacterial flora) • Beneficial bacteria • Control pathogenic bacteria • Synthesize Vitamin K and Biotin • Aid dig and fermentation of fibers • Probiotics • Live bacteria in food &supplements • Health benefits • Prebiotics • Non digestible carbohydrates in food that promote the growth of bacteria- • E.g. inulin, resistant starch

  16. Heartburn and Gastroesphogeal reflux disease (GERD) Foods that increase reflux: Citrus, caffeine, chocolate, fatty foods, spicy foods, onion, garlic and tomato based foods (Peptic) Ulcers Causes: H. pylori and NSAID medications Treatment: Medications Avoid foods that increase symptoms When Digestive Processes Go Awry

  17. Food Intolerances Intestinal Gas (Flatulence) Constipation Fiber, fluid and exercise Laxative use Diarrhea Replace fluid and electrolytes Irritable Bowel Syndrome (IBS) Cause unknown Inflammatory Bowel Disease (IBD) Ulcerative colitis and Crohn’s disease Hemorrhoids Gallstones When Digestive Processes Go Awry (2)

  18. Celiac Disease • Intolerance to gluten • 1 in 133 people affected • Many undiagnosed • Can affect many body systems • GI and others • Gluten-free diet for life • Corn, rice, quinoa, and buckwheat OK

More Related