The Human Digestive System Chapter 11

1. The HumanDigestive SystemChapter 11

2. What is the Purpose of the Digestive System? The DIGESTIVE SYSTEM breaks down large food masses into smaller useful substances that can be absorbed into and transported by the circulatory system to the individual cells

3. 1. Mechanical Digestion • Initial stage of physically breaking down food into smaller pieces • Occurs in the mouth

4. 2. Chemical Digestion • The separation of food into its molecular components by chemicalmeans. • Occurs in the mouth with the secretion of digestive enzymes in saliva • Continues in the stomach and finishes in the small intestine

5. What is the Relationship between Mechanical and Chemical Digestion? • The two work together to provide the nutrients that are absorbed into the body! • Mechanical digestion breaks the food into smaller pieces so that chemical digestion can occur more easily

6. What makes up the Digestive System? • Salivary Glands (Mouth) • Stomach • Liver • Pancreas • Gall Bladder • Small Intestine • Large Intestine

7. Digestive System • Mouth • Physical and chemical breakdown • Salivary Glands • Release saliva to lubricate food • Assist in the chemical process of digestion • Release salivary amylase to break down starch

8. 3 Pairs of Salivary Glands(do not need to know)

9. Teeth • Grind food • Tongue • Muscle • Manipulates food • Has taste buds

10. Teeth

11. Uvula • Prevents food from moving up the pharynx • Esophagus • Carries food to stomach • Has circular muscles (push food down)

12. Food Movement • Peristalsis • Wave like muscle contractions of the digestive system

13. Stomach • Muscular J-shaped organ • Physical (churning) and Chemical (HCl and pepsin) digestion

14. Sphincters • Esophageal sphincter • At top of the stomach • Prevents food from going back up the esophagus • Pyloric Sphincter • At bottom of the stomach • Slows/Stops food from entering the duodenum until well “mixed”

15. Stomach: Note the rugae & sphincters

16. Small Intestine • The small intestine is divided into 3 regions: • Duodenum • Jejenum • Ileum • Most products of digestion are reduced to nutrients and absorbed along its length

17. Small Intestine

18. Surface Area and the Small Intestine • The small intestine has folds in its mucous membrane, increasing surface area and therefore increasing absorption of nutrients • Contains: • Villi • Microvilli

19. Small Intestine Wall • Villi (villus) • Small finger like projections on the folds of the small intestine • Increase surface area by 30X • Contains blood and lymph to absorb and distribute nutrients

21. Large Intestine • Final portion of the digestive system • About 1.5m long • Consists of: • caecum • colon • rectum • anal canal

22. Caecum • Where the small intestine meets the large intestine • Colon(ascending, transverse, descending) • Main portion • Removes water and minerals • Contains bacteria that help with breakdown

23. Rectum • Lower portion • Hold waste until body is ready to void • Anus • Has rings of muscles (anal sphincter) • Allows timing of waste elimination

24. Other Related Organs Liver Makes bile from cholesterol Recycles RBCs and filters toxins from the blood Bile Stored in the gallbladder Released into duodenum via bile duct Breaks down fats Activates lipase

25. Gall Bladder Storage warehouse for bile produced in the liver

26. Pancreas Small gland near the small intestine Makes enzymes to digest carbohydrates, fats and proteins Secretes neutralizing agent (sodium bicarbonate) into duodenum to increase pH so enzymes can start working Produces insulin

27. The Digestive System • Digestive System (~11 mins) • Digestive System Rap (~3 mins)

29. P A T H W A Y O F F O O D

30. What are the 6 Essential Nutrients? Carbohydrates Lipids Proteins Vitamins Minerals Water

31. 1. Carbohydrates • Carbon, hydrogen and oxygen • “Burned” to make energy • Can be held in energy stores • Plants = Starch • Animals = Glycogen • Sources • Grains, Sugar, Fruit, Pasta

32. Broken down into simple sugars (ex: glucose, fructose) Glucose + Glucose = Maltose + Water (2 Monosaccharides) = (1 Disaccharide + Water) Dehydration  Makes Maltose Hydration  Reverses it

34. 2. Fats (Lipids) • Building block • In cell membranes and hormones • Make energy • Insulation • Store minerals and vitamins • Conduct nerve impulses • Is broken into fatty acids and glycerol in the small intestine • Sources • Nuts, Seeds, Meat, Cheese, Butter, Cooking Oils

35. Cholesterol • Lipid found in body cells and circulatory system • Functions • Insulates nerves • Supports cell membrane • Used in making hormones • Sources: Made in your liver • Diet: Meat, Eggs, Dairy

36. 3. Proteins Amino acids combine = Polypeptide Polypeptides combine = Protein Proteins are broken down into amino acids during digestion

37. Function • Form enzymes, antibodies and hormones • Build and repair muscles • Source • Meat, Legumes, Eggs, Cheese & Milk

38. 8 Essential Amino Acids 20 amino acids exist We make all but 8 The essential 8 come from diet (eggs, legumes, meat, dairy, nuts) Complete proteins: Contain all 8 essential amino acids

39. 4. Minerals Inorganic compounds needed in small doses Used in: Bones, cartilage, hemoglobin, hormones, enzymes, vitamins, metabolic reactions Ex: Iron, Magnesium, Calcium

40. 5. Vitamins • Required in small amounts • Main-function: • Co-enzymes: Help enzymes function (Enzymes break down complex molecules)

41. Vitamins • Vitamin A • Antioxidant • Found in fruit, veggies, milk, butter, eggs • Lack of Vitamin A can lead to night blindness and poor bone growth • Vitamin D • Found in milk, fish-oil, skin (with sunlight) • Need Vitamin D to absorb calcium • Lack of Vitamin D can lead to weak, brittle bones

42. Night Blindness (Lack of Vitamin A)

43. Vitamin D deficiency affects bone growth

44. Vitamin E • Antioxidant • Found in green vegetables, nuts, grains • Lack of: Unknown/Undecided • Vitamin K • Used in blood clotting/coagulation • Found in green vegetables, bananas • Lack of Vitamin K: Easy bruising & bleeding

45. Vitamin C • Collagen synthesis (cartilage, skin, bone..) • Found in citrus fruits, sunlight • Lack of Vitamin C can lead to scurvy (skin haemorrhaging, weak bones, sore gums, poor healing)

46. 6. Water • Water transports other nutrients to cells, carries wastes away, aids digestion and more. • It makes up more than half your weight. • SOURCES: water; juices and other beverages; soups and many "solid" foods (fruits, vegetables, breads, etc.). • Worksto keep muscles and skin toned • Aids in weight loss • Transports oxygen & nutrients to cells • Eliminates toxins & waste from the body • Regulates body temperature

47. How do we convert large molecules to smaller ones? There are two steps in this process: 1. MECHANICAL DIGESTION 2. CHEMICAL DIGESTION Both allow nutrients to be absorbed

48. Chemical Digestion & Enzymes Dehydration • Small molecules combine to form a larger one by removing atoms that form water Examples: Amino Acid + Amino Acid = Protein + Water 2 Monosaccharides = 1 Carbohydrate + Water

49. Hydrolysis • Breaking of large molecules into smaller ones by adding water • The reverse of Dehydration

50. Enzymes • Speed up hydration and dehydration (I.E. Digestion) • Function is affected by • Temperature • pH • Inorganic micronutrients