Digestive System

1. Digestive System Turn in your ch. 41 reading guide if you didn’t last week I will hand your reading guides back shortly Homework Ch. 44 reading guide due Wednesday Digestion Quiz on Thursday

2. Today • Review – homeostasis, organic compounds, enzymes • Types of feeding • Types of digestion • Know the parts of the mammalian digestive system

3. It’s all about Homeostasis • Cells of the pancreas monitor blood glucose levels • High levels  release insulin  body cells and liver take up glucose  stored as glycogen • Low levels  release glucagon liver breaks down glycogen  releases glucose into blood

4. glucose Feedback Mechanism in pancreatic cells

5. Problems when sugar is too high or too low • Hyperglycemia (Diabetes) – blood sugar levels too high • Type II – fats cells are more resistant to insulin over time • Hypoglycemia – low blood sugar levels • Too much sugar in the blood  cardiovascular disease • Insulin (Diabetic) shock  brain function is affected first, disorientation, aggressiveness, slurred speech

6. Type I vs Type II Diabetes

7. Overnourishment Undernourishment

8. Weight Regulation

9. Anorexia nervosa • Medical consequences • Shrunken bones • Mineral loss • Low body temp. • Irregular heartbeat • Permanent failure of normal growth • Osteoporosis • Use of laxatives – increased risk of colon infection and stretched colon • Miscarriages

10. Acid reflux/Bulimia • Cancer • Ulcers • Scar tissue – blockage of food • Asthma • Infection

11. Time for Digestion 30 sec 5-6 sec 2-4 hrs 5-6 hrs 12-24 hrs

12. Digestion • Process of breaking down food into smaller molecules that can be used by the cell • Digestion breaks down organic compounds (protein, carbs, etc.) into their components so the body can use to them for energy or building blocks for other compounds • You are what you eat!

13. Amino Acids

14. Vitamins/Minerals • Vitamins – organic, required in small amounts • Water-soluble (B,C) – coenzymes needed for macromolecule metabolism, collagen synthesis • Fat-soluble (A,D,E,K) – visual pigments, calcium absorption, blood clotting • Minerals – inorganic molecules • Calcium – bone formation, muscle contraction • Iron – electron carriers, Oxygen transport (hemoglobin)

15. Nourishment • Malnourishment – occurs when there is an absence of 1 or more essential nutrients • Undernourishment – getting less chemical energy (calories) than you need

16. Malnourishment – deficiency in a nutrient • Scaly skin – deficiency of Biotin, Zinc • Hair loss – vitamin A • Many deficiencies in nutrients will cause irratibility

17. Feeding mechanisms – add these Substrate-feeders Suspension-feeders Deposit-feeders Bulk-feeders Fluid-feeders

18. Stages of Food Processing • Ingestion • Digestion – hydrolytic enzymes • Absorption • Elimination

19. Intracellular Digestion • Ingestion – phagocytosis, pinocytosis • Digestion – hydrolytic enzymes contained in lysosomes • Absorption – simple diffusion • Elimination - exocytosis

20. Extracellular Digestion – can eat larger prey Gastrovascular cavity Complete digestive tracts (alimentary canals) – allow for systematic Food processing in specialized regions 2 openings 1 opening

21. Types of digestive systems • Sponges– all intracellular digestion using diffusion, thin layers of cells • Hydra– enzymes in gastrovascular cavity break down food, cells then absorb it directly, thin layers of cells • Earthworms and Birds – alimenatary canals, specialized compartements, • Crop – storing food • Gizzard – grinding food

23. What you should know • Each step of the digestive process • Name of organ • Structural adaptations • Type of digestion (mechanical, etc.) • Enzymes involved

24. Digestion • http://kitses.com/animation/swfs/digestion.swf • http://highered.mcgraw-hill.com/sites/0072943696/student_view0/chapter16/animation__organs_of_digestion.html

25. 9 • Mechanical Digestion – the physical breakdown of large pieces of food into smaller pieces • Chemical Digestion – the process that turns complex molecules (fats, carbohydrates, proteins) into smaller molecules to be used by cells (enzymes involved)

26. II. Functions • Mouth • Teeth – used to tear, cut, and crush food into small fragments (Mechanical) • Saliva – • Makes food slippery for easy swallowing • Begins chemical digestion of the food with help from enzymes – a protein that speeds up (catalyzes reactions) • Amylase – breaks bonds in starches to release sugar • Lysozyme – another enzyme that fights infection by breaking down the cell wall of bacteria that may be in the mouth

28. Esophagus • Tongue and throat muscles push the ball of food down your throat • To ensure the food does not go down the trachea (windpipe), the epiglottis (flap of tissue) covers the opening to the trachea • After passing through the throat, the food passes through the esophagus by peristalsis – rhythmic contractions of the smooth muscle

29. Peristalsis • http://www.mennellmedia.co.uk/VideoProjects/Peristalsis/Peristalsis.html

30. Stomach • The food passes to the stomach next where further mechanical and chemical digestion will occur • Chemical Digestion • Hydrochloric Acid (HCL) and Pepsin – begin digestion of protein • Mechanical Digestion • Stomach muscles contract to churn and mix stomach fluids creating a mixture called Chyme.

31. Gastric Pits

32. Stomach enzymes • Chief cells – release pepsinogen • Parietal cells – release HCl • HClactivates pepsinogen to pepsin when both fluids mix in the stomach (pepsin also can activate pepsinogen – positive feedback) • Mucus cells – secrete mucus to prevent degradation of the stomach lining

33. Warm-up (10/2) • Have out ch. 41 notes • What do the following do: • Chief cells • Parietal cells • Mucus cells • Pepsinogen • HCl • Amylase • Lysozyme

34. Today • Objectives • Look at structure and function of the small/large intestine, gall bladder, liver, and pancreas • Look at how the digestive system is regulated • Understand differences in the digestive systems of carnivores and herbivores • Homework • Ch. 44 reading guide – due tomorrow • Digestion Quiz - Thursday

36. Small intestine/fat digestion • http://bcs.whfreeman.com/thelifewire/content/chp50/5002001.html

37. Small Intestine • Completes digestion by dissolving the fat • Bile from the liver - breaks down the fat • Lipase – digests the fat • Absorption of the nutrients into the bloodsteam occurs through villi (fingerlike projections lining the small intestine). Villi increase surface area and therefore the absorption rate

38. Absorption of nutrients • Sugars and vitamins – diffuse through facilitated diffusion or active transport • Lipids – diffuse out through exocytosis in globules known as chylomicrons, diffuse into the lymph system • Most nutrients pass into the bloodstream to the hepatic portal vein which travels to the liver • Benefits: • Solute concentration equalization • Ridding of toxins

39. Small Intestine • Length – 6m – allows for 80 to 90% of organic matter to be absorbed • Villi/microvilli – increase the surface area of the small intestine to 300 m2 – more absorption • Close association with blood vessels (2 cells away) – allows for quick absorption and transport throughout body

40. Accessory Glands • Pancreas • Releases bicarbonate – offsets acidic chyme • Releases amylase – finish carb digestion • Releases lipase – digests fat • Liver • Release bile – aids in emulsification of fats • Gall bladder • Secrete bile salts – emulsify fats

41. Fat digestion • http://www.biologyinmotion.com/bile/index.html

43. Positive feedback mechanism

45. Large Intestine • All that makes it to the large intestine is water, cellulose, and other undigested molecules • Water is reabsorbed back into the body through the wall of the large intestine • The concentrated waste material (feces) is then passed out of the body through the rectum

46. Large Intestine • Reabsorbs H2O • Symbiotic relationship with E. coli • E. coli – produces methane, H2S, vitamin K and B

47. Constipation CAUSES • not enough fiber in the diet • lack of physical activity (especially in the elderly) • medications • milk • irritable bowel syndrome • changes in life or routine such as pregnancy, aging, and travel • abuse of laxatives • ignoring the urge to have a bowel movement • dehydration • specific diseases or conditions, such as stroke (most common) • problems with the colon and rectum • problems with intestinal function (chronic idiopathic constipation) Normal deffication – 3 times/day to 3 times/week

48. Flatulence • Gases ingested and produced by bacteria and protists in digestive tract create flatulence • You pass a quart of gas a day • Methane & hydrogen – flammable • Skatole, indole, and H2S – odorous • Broccoli and cabbage can add to odor • Spices could counteract flatulence

49. http://kidshealth.org/PageManager.jsp?lic=1&article_set=59299&cat_id=20607http://kidshealth.org/PageManager.jsp?lic=1&article_set=59299&cat_id=20607

50. What you should know • Each step of the digestive process • Name of organ • Structural adaptations • Type of digestion (mechanical, etc.) • Enzymes involved