DIGESTIVE SYSTEM

1. DIGESTIVE SYSTEM

2. Purpose for digestive system • To break down food into useable nutrients that can be absorbed and transported to cells throughout body • Remember – we are heterotrophs!

3. NUTRITIONThe Study of What we Eat What it does to the body What it does for the body…Biology, Chemistry, and Physiology. WHY WE EAT WHAT WE EAT ? Personal Preferences Social Values and Beliefs Temptation Reward or Consolation

4. We need… • water, salts • Vitamins and minerals – to maintain overall health • Macromolecules • Carbs for energy • Proteins for building and repairing of tissues • Lipids for stored energy source, brain development (babies), essential for fat-soluble vitamins

5. ANATOMY- know pathway food travels

6. PHYSIOLOGY of human digestive tract • Two main parts • Alimentary canal – the tube or pathway that the food travels through • Accessory glands – outside of the “tube” but aid in digestion by secreting enzymes into the tract

7. Accessory glands • Fill in the enzymes they secrete as we go through the whole process • Salivary gland – • Pancreas – • Liver – • Gall bladder –

11. How does the Peanut Butter and Jelly sandwich we eat for lunch become the vitamins our body needs?? • Must be broken down into simpler substance and absorbed into the bloodstream

12. Digestive System • Alimentary canal= a long winding tube (with openings at each end) made of organs through which food passes . Mechanical digestion = breaking down, mashing food Chemical digestion = changing food into simpler substances using enzymes

13. DIGESTION • The Mouth • Salivary glands=Secretion of saliva • Contains amylase (enzymes) breaks down carbohydrate chains. • Tongue assesses the amounts and type of tastes found in saliva, and pushes the food down The Esophagus • Tube through which food is transported with peristaltic motion

14. Pharynx • Pharynx – passageway for both air into lungs and food into esophagus • epiglottis – blocks trachea when swallowing so bolus (food ball) enters the esophagus

15. Opening called the glottis is covered by a flap called epiglottis. Which prevents choking by covering the trachea (breathing tube) when swallowing. • The Stomach • Digests proteins using gastric juices. • Enzymes=gastrin and pepsin helps in large proteins. The pH of stomach is critical to the activation of pepsin.

16. Average capacity is one liter. • Food stay is stomach 2 to 3 hours. • Fatty meals or solid food takes longer to digest then liquids or low fat meals. • Absorbs only alcohol, water and a little fat • Most of major nutrients are absorbed in the small intestines. • The thick liquid/partially digested food becomes chyme

17. Stomach • gastric juice • pepsin • mucous

18. The Small Intestine • Duodenum The first part of the small intestine where most chemical digestion begins • Small intestine can be up to 10 ft. or longer • Food may remain from 4 to 10 hrs. • Most digestion occurs here. • Villi increase surface area for absorption

19. Small Intestines – the main player

21. Inside lining of Small Intestine MAJOR SURFACE AREA FOR MAJOR ABSORPTION!

22. Asorption of nutrients in the small intestine • capillaries receive – carbohydrates and proteins • Nutrient rich blood from S.I. is carried via hepatic portal vessel to the liver • Liver is in charge of distributing nutrients to blood (and rest of body

23. Asorption of nutrients in the small intestine • Lacteals receive – packaged lipids • These lead to the lymphatic system which carries the lipids to the heart

24. The Pancreas • Long soft gland lying behind the stomach • Secretes enzymes into the duodenum…trypsin,amylase,bicarbonate • Tiny intestinal glands are in lining of small intestine. • The liver supplies duodenum with bile.

25. Bile =A yellow-green juice acts like a dish detergent and breaks fats into little globules for fat digestion • Absorption of nutrients into the blood occurs throughout the wall of the small intestine • The intestine wall contains millions of tiny finger-like projections called villi. • Each villus contains a network of blood vessels (capillaries) • Blood carries these nutrients to liver before it goes to rest of body.

26. Functions of The Liver • Changes surplus glucose to glycogen for storage until glucose is needed. • Secrets bile • Stores fat • Breaks down and stores amino acids used to form proteins. • Detoxifies alcohol and drugs • Stores vitamins A, D, E, K, and B12 • Stores iron for use in red blood cells

27. The Large Intestine • The large intestine (colon) • Can be up to 6 ft. long • Holds food for as much as 3 days • Major function is to reabsorb the water used during digestion and the absorption of vitamins produced by bacteria that live there and elimination • Bacteria are permanent residents

28. Large Intestine

29. Bacteria aid in the digestion of plant matter. • Bacteria produce vitamins B-12, riboflavin, thiamine, and vitamin K for absorption in the large intestine. • Water is removed from food. • Waste matter is packaged for removal ( about ½ of it is dead bacteria)

30. Biochemistry of Food

31. THE SIX BASIC NUTRIENTS Nutrients That Provide Energy • Carbohydrates…simple & complex • Fats…saturated & unsaturated • Protein…build and repair Nutrients That Regulate • Vitamins…fat & water soluble • Minerals…major & trace minerals • Water…most abundant nutrient

32. Energy = Calories • Food energy = Calories • 1 Calorie=1kcal=1,000 calories

33. Biochemical Review • Protein • Carbohydrate • Lipid

34. Proteins • Proteins=CHONS • Amino acids are the smallest units • Complete proteins= contain all essential amino acids, come from animal products • Incomplete proteins=contain some amino acids ex. Vegetables, grains, beans, etc.

36. Carbohydrates • Sugars = CHO • simple= fructose, glucose, lactose, sucrose • complex= starches, fibers

38. Simple sugars

40. Complex Carbs

41. Fats • Fats = Lipids • Lipids do not dissolve in water • Most concentrated form of energy • Satisfied feeling • Saturated- solid @ room temperature • Unsaturated- liquid @ room temperature

43. Saturated vs Unsaturated Fats

44. Cholesterol • Found in foods that come from animals • LDL= Good cholesterol • HDL= Bad cholesterol

45. Biochemistry of Food

46. THE SIX BASIC NUTRIENTS Nutrients That Provide Energy • Carbohydrates…simple & complex • Fats…saturated & unsaturated • Protein…build and repair Nutrients That Regulate • Vitamins…fat & water soluble • Minerals…major & trace minerals • Water…most abundant nutrient

47. Vitamins • Compounds found in living things needed for life growth • Prevent disease • Found in foods • Look at chart on p. 214

48. Minerals • Simple substances found in the environment, essential to the body’s functioning • Ca, Mg, P, K, Na, Cl • Regulate the body’s processes: building bones, clotting blood • Osteoporosis= lack of Ca, weak and brittle bones • Hypertension= high blood pressure, caused by too much Na

49. Energy = Calories • Food energy = Calories • 1 Calorie=1kcal=1,000 calories

50. THE FOOD GUIDE PYRAMID A Guide to Daily Food Choices • Guidelines for making food choices by grouping foods and recommended number of servings from each group