1. Digestive System & Diet
SBI 3U
Ms. Raper

2. All organisms need to obtain energy from essential nutrients.
Heterotrophs get energy from other organisms.

3. Plants are Autotrophs, they make food from simple substances
They use the process of photosynthesis to make food.

4. What is Diet?
Diet is everything you eat and drink

5. Different food groups Carbohydrates Proteins Fats & lipids
Starches
Sugars
Fiber
Proteins
Fats & lipids
Vitamins & Minerals
Water

6. Healthy Diet

7. Canada’s Food Guide

8. U.S. Food Pyramid

12. Vegetarian Food Pyramid

13. Heart Healthy Pyramid

14. Indian Food pyramid

16. Want some fun? Check this out…..

17. How much do you need? Food provides nutrients for
Energy
Material for growth and repair
Health
Energy is measured in Joules (J)
Number of joules/day depends on:
Age
Gender
Occupation/activity level

18. The 5 processes.... Ingestion: taking in food (eating)
Digestion: breaking down food into simpler
substances.
Absorption: digested food passes into the
blood.
Assimilation: Digested food is used by
cells of the body.
Egestion: Elimination of waste undigested
food.

19. What happens to the food you eat?
Food is made of complex insoluble macro-molecules.
Has to be broken down into small soluble micro-molecules (glucose, amino acids, fatty acids and glycerol)
Breaking down food into small soluble molecules is called DIGESTION.

20. Digestion Two types Mechanical Chemical Teeth Muscular contractions
Enzymes

22. Digestive system
A long tube starting at the mouth and ending at the anus

23. The digestive system consists of
A tube lined with glandular cells that secrete digestive juices and enzymes
Associated organs
Liver
Pancreas
Gall bladder
Salivary glands

24. Mouth Mechanical digestion Chemical digestion
Teeth break food into smaller pieces that increases the surface area for digestion
Saliva creates a basic pH of about 8 & moistens food allowing soluble chemicals to dissolve.
Chemical digestion
3 pairs of Salivary glands produce the enzyme AMYLASE – this begins the breakdown of STARCH

25. Salivary Glands
Chewed food is mixed with saliva from 3 pairs of salivary glands, the food is now called a BOLUS

26. Swallowing…

28. Food is pushed down the esophagus by muscular waves called PERISTALSIS

29. Peristalsis

30. The Stomach Food enters the stomach through a valve known as the
CARDIAC SPHINCTER
The stomach churns the food like a blender.
Food is liquefied and now is known as CHYME
Food stays in the stomach for several hours

31. The stomach
“Epithelial cells line inner surface of the stomach, and secrete about 2 liters of gastric juices per day. Gastric juice contains hydrochloric acid, pepsinogen, and mucus; ingredients important in digestion. Secretions are controlled by nervous (smells, thoughts, and caffeine) and endocrine signals. The stomach secretes hydrochloric acid and pepsin. Hydrochloric acid (HCl) lowers pH of the stomach so pepsin is activated. Pepsin is an enzyme that controls the hydrolysis of proteins into peptides. The stomach also mechanically churns the food. Chyme, the mix of acid and food in the stomach, leaves the stomach and enters the small intestine.”

32. The Pancreas Produces digestive juices through the pancreatic duct.
Produces enzymes that digest carbohydrates, proteins and fats.
Produces bicarbonate salts to neutralize the stomach acid.
The pancreas is also an endocrine organ that produces insulin and glycogen to help in the metabolism of sugar

33. Gall bladder Lies under the liver Stores bile – a greenish liquid
Bile emulsifies fats.
Has a common duct with the pancreas

34. http://www. emc. maricopa. edu/faculty/farabee/biobk/BioBookDIGEST

35. Small Intestine
The small intestine is where final digestion and absorption occur. The small intestine is a coiled tube over 3 meters long. Coils and folding plus villi give this 3m tube the surface area of a m long tube. Final digestion of proteins and carbohydrates must occur, and fats have not yet been digested. Villi have cells that produce intestinal enzymes which complete the digestion of peptides and sugars. The absorption process also occurs in the small intestine. Food has been broken down into particles small enough to pass into the small intestine. Sugars and amino acids go into the bloodstream via capillaries in each villus. Glycerol and fatty acids go into the lymphatic system. Absorption is an active transport, requiring cellular energy.

36. Small intestine continued
Has an increased surface area due to fingerlike projections called VILLI
Produces enzymes that complete the digestion of carbohydrates, proteins and fats.
Consists of 3 areas
Duodenum
Jejunum
Ileum

37. Villi

38. Villus

39. Absorption in Villi

41. Liver

42. Liver… Detoxifies poisons such as alcohol Stores glycogen
Deanimates proteins (breaks them down into urea)
Produces bile salts
Recycles hemoglobin from red blood cells
Produces heat

43. Large Intestine & Appendix
Comprised of the ascending, transverse, descending and sigmoid colon
Absorbs water, vitamins and minerals
Stores waste (feces)
Eliminates feces through the anus

45. Appendix/caecum In humans the appendix has no known function.
In herbivores such as rabbits the appendix or caecum is used to digest cellulose.

46. Conclusion: 5 steps of the process..
Ingestion - taking in food.
Digestion – breaking down food.
Absorption – digested food goes into the blood.
Assimilation – digested food is used by the body.
Egestion:- Elimination, waste is removed from the body.

47. Summary of Digestive Enzymes
FOOD TYPE
ENZYME
SOURCE
PRODUCTS
CARBOHYDRATES
Salivary amylase
Pancreatic amylase
Maltase
Salivary glands
Pancreas
Small intestine
Maltose
Glucose
PROTEINS
Pepsin
Trypsin
Peptidases
Stomach mucosa
Intestinal mucosa
Peptides
Amino acids
FATS
Lipase
Fatty acids and glycerol

48. Enzymes by source SOURCE ENZYME FOOD PRODUCT MOUTH (salivary glands)
Salivary amylase
Polysaccharides
Maltose
STOMACH
Pepsin
Proteins
Peptides
PANCREAS
Pancreatic amylase
Trypsin
Lipase
Fats
Fatty acids
and glycerol
SMALL INTESTINE
Maltase
Peptidases
Glucose
Amino acids

49. Resources http://www.innerbody.com/htm/body.html l

50. Salivary gland Teeth Tongue Epiglottis Esophagus Liver Stomach
Gall Bladder
Duodenum
Bile duct
Pancreas
Colon
(Large Intestine)
Small Intestine
Appendix
Rectum
(Anus)

51. Pancreas
Gall Bladder
Pancreatic Duct
Bile duct
Duodenum

52. Cells produce enzymes and
Epithelial Lining
Cells produce enzymes and
absorb digested food
Artery
Lymph vessel
Vein

53. Digestion of Starch
“Carbohydrates are digested in the mouth, stomach and small intestine. The saliva in your mouth contains amylase. If you chew a piece of bread for long enough, the starch it contains is digested to sugar, and it begins to taste sweet.” BBC. Bitesize biology,

54. Digestion of Proteins
“Proteins are digested in the stomach and small intestine. Digestion of proteins in the stomach is helped by stomach acid, which is strong hydrochloric acid. This also kills harmful micro-organisms that may be in the food.” BBC; bitesize biology.

55. Digestion of Fats (lipids)
“Digestion of fat in the small intestine is helped by bile, made in the liver. Bile breaks the fat into small droplets that are easier for the lipase enzymes to work on.” BBC; bitesize Biology

56. http://www. bbc. co. uk/schools/ks3bitesize/science/biology/diet_5