1. Travel Brochure of the Digestive System
Duodenum Dynamics Ad Agency
Manager: Vella Liu 11B

2. A luxury tour
The Digestive System!!! The most fabulous tourist destination ever! You just need to take nearly a week, enjoy the beautiful scenes (Biology is beautiful!) and get better understanding of your body.
You will become a bolus and travel along the path of the Digestive system
Fee: for adult $200/person
for children $100/person
insurance $20/person 2

3. Our destinations
Compare mechanical digestion to chemical digestion P4--5
List the parts of the digestive system and give their functions, potential risks& Describe the structure of the villi and explain how its function is related to its structure P7--30
Discuss the importance of the liver and pancreas in digestion. List the substances they produce and explain their function. P32--37
Explain the results of the chemical digestion of carbohydrates, proteins and fats and discuss if this digestion occurs in the mouth stomach and/or small intestines & Explain the function of the digestive enzymes (amylase, protease and lipase) P39--43 3

4. mechanical digestion v.s chemical digestion
What? Physically breaks down the food
Where and How?
1.In oral Cavity, the teeth chew the food
2. In the stomach, it’s the churning and mixing food
Mechanical digestion works similar to the electronic blender 4

5. Why? Food can be absorbed more easily.
Chemical digestion
What? Breaking down food macromolecules to smaller molecules by enzymes (different enzymes have different functions)
Why? Food can be absorbed more easily.
Where? Oral cavity, stomach, intestines. 5

6. Let’s start our alimentary canal tour!
Each part of the digestive system is a tourist attraction
Each digestive system malfunction or disease will receive a caution. (That’s what your insurance for) 6

7. Oral Cavity What? A fancy way to say “mouth”
Function: receive & store food while the teeth are chewing it. (without this closed area, the food will never ever get into your stomach)
Made up of:
Lips: hold the food (like the guard of oral cavity)
Teeth: physically break down food into bolus
Tongue: directs food towards teeth, and then directs bolus towards the pharynx 7

8. Important features: Salivary glands Function: produce saliva
Saliva’s function:1.makes food wet (become slippery and be easily swallowed)
2.Contains enzymes break down starch into carbohydrates (the last part of ppt will describe enzymes in details)
3.locations of salivary glands: Sublingual gland (beneath the tongue), Submandibular gland (beneath the floor of the mouth), Parotoid gland (right in front of ears, on the cheek ) 8

9. 2.Pharynx 2.1 Where? 1.Back of the throat
2.Includes oral and nasal cavities & where they join 9

10. 2.2 Important features Epiglottis 1.Covers the glottis
2.The entrance of trachea
3. Close when swallowing happens
Why? Preventing the bolus goes to wrong way 10

11. 2.3 extra information: swallowing
Process:
Reflex action:1.bolus moves down to the throat
2.soft palate closes the nasopharynx, epiglottis closes the trachea
3. bolus moves down to the esophagus, peristalsis (explained later) happens 11

12. 3.The Esophagus
3.1 What? Muscular tube, joins the pharynx and the stomach, expands only when bolus comes down
3.2 Function: passageway, pushes bolus downwards to the stomach through peristalsis 12

13. 3.3 Important process: peristalsis
What? Rhythmic contraction squeezes bolus downwards
Location: the esophagus, continues in all the organs of the digestive pathway (i.e. the intestine tract)
Explanation: the area above the bolus squeezes; however, the bolus and the area below the bolus are relaxed. As a result, it’s easy to push bolus downwards 13

15. 4. The stomach
4.1 Structure: J-shaped, thick wall with folds (rugae), mucous on the inside surface
4.2 Location: left side of the body, below the liver, above the pancreas
4.3 Function: 1.stores food
2. Churns food, helps digesting food physically product: acid chyme
3. Begins digestion of protein
4. Moves food to the small intestine 15

16. 4.4 sphincters Cardiac Sphincter Band of muscle
At the top of the stomach
Function: 1.prevent stomach acid from entering the esophagus
2.Opens when bolus enter to the stomach
Pyloric Sphincter
Band of muscle
At the bottom of the stomach
Function:1.acid chyme can’t easily escape
2. Allows small amounts of chyme entering the duodenum 16

17. 4.5 Caution (additional info)
4.51 Heartburn
Gastric juice escapes the guarding (cardiac sphincter) enters the esophagus The pain often rises in the chest, may radiates to the neck, throat, or angle of the jaw.
Internal fire, rising from the stomach 17

18. 4.52 gastric perforation
What? The mucous (internal layer) of the stomach The penetration of the wall of the stomach exists a hole stomach contents escape into the abdominal cavity
Harm: potential bacterial infection to the abdominal cavity & entire body 18

19. 4.6 gastric juice 4.61 stomach acid Mainly: HCl acidic pH
Function: 1.prodives the optimum pH for pepsinogen to work
2. Kill bacteria inside the food
4.62 pepsinogen
Importance: changes into pepsin (enzyme) when exposed to HCl
Pepsin function: break down protein into peptides

20. 5. Duodenum First 25cm of the small intestine
Contain ducts connected with the gall bladder and the pancreas
Bile and pancreatic juice come and join here (details explained later)
Duodenum and internal surface 20

21. 6. The Small Intestine 6.1 Diameter: small 2.5cm Distance: long 7m
6.2 Function: 1. further digestion
2. Absorption of nutrients
6.3 Important feature:
Villi, microvilli, lacteals
Villi: projection, finger like, epithelial cells on the outside
Microvilli: on the epithelial cells, similar structure 21

22. Function of villi and microvilli: the shape of them increase surface area more site for absorption
Lacteal: blood capillaries (even microvilli have these) + lymphatic capilary
How it function: absorbs the nutrients (i.e. fatty acids and amino acids), and they will travel through the veins, be used by the cells of the entire body 22

23. 23

24. 7.Appendix
7.1 Location: at the junction of the small intestine and colon (connect them)
7.2 Function: no functions in human bodies 24

25. 7.3 appendicitis (extra info)
Inflammation of the appendix
How it forms: the food goes into the wrong way, it accumulates inside the appendix, the appendix may burst, and the result may cause death 25

26. 8. The large intestine (colon)
8.1 consists of : cecum (the first length of it), ascending colon, transverse colon, descending colon, sigmoid colon
8.2 Diameter: larger 6.5cm
Distance: shorter 1.5m
8.3 Escherichia coli: the colon is there home
Break down some indigestible material, produce some vitamins and molecules, beneficial to humans 26

27. 8.4 Function:1. absorbs water, salts, vitamins
2. Forms the indigestible wastes as feces 27

28. 9. Pelvic Cavity 9.1 Rectum Structure: pouch like, enlarged portion
Function: stores undigested food (feces) for a short period of time
rectum 28

29. 1.A sphincter = a band of muscle
9.2 Anus
1.A sphincter = a band of muscle
2. Allow undigested wastes (feces) to exit the body
3. Why this is important? Without it, we can’t control the feces getting out of our bodies, so it will cause gatism 29

30. The important process: Elimination / defacation
4.By the way------
The important process:
Elimination / defacation
Discharge of feces from the rectum through the anus 30

31. Let’s zoom in the liver and the pancreas!
special top 2 tourist attractions

32. 10. The Liver 10.1 Function: 1. produce bile
2. Destroys old red blood cells, converts hemoglobin to the bile
3. After eating: stores glucose as glycogen
Between eating: breaks down glycogen into glucose
4. deamination: breaks down amino acids & produces urea 32

33. 5. (also) produces blood proteins from amino acids
6. Detoxifies and metabolizes poisonous substances
10.2 Importances:
Maintain the blood glucose level
bile: emulsifies fats= breaks fats down into fat droplets easier for body to absorb fat molecules 33

34. 11. The Gall Bladder Function: stores the bile
Process: 1.acid chyme stimulates the duodenal wall
2.release cck
3.stimulates the release of bile 34

35. 12. The Pancreas 12.1 Both an Exocrine and an Endocrine organ
12.2 Exocrine: enzymes
Pancreatic amylase: breaks downstarch into maltose
Trysin (protease): breaks down protein into peptides
3. Lipase: breaks down fat droplets into glycerol and fatty acids

36. 12.3 Endocrine (produces hormones)
Insulin
Function: lower the blood concentration
Makes liver and muscles store spare glucose
Helps synthesis of protein, fats
glucagon
Function: increases the blood concentration
Makes liver and muscles break down glycogen
Stops synthesis of protein, fats

37. 12.4 sodium bicarbonate NaHCO₃ (basic)
Function: be secreted by the pancreas in order to neutralize the acid in the acid chyme (get a neutral pH, the duodenum doesn’t have the mucous like the one the stomach has)

38. The results of the chemical digestion of organic molecules
& Let’s get to know some friends!!
(function of the enzymes)

39. 13.carbohydrates Process: hydrolysis 13.1 Enzyme: Salivary amylase
Location: mouth
Produced by: salivary glands
Function: starch + H2O  maltose
13.2 enzyme: Pancreatic amylase
Location: small intestine (the duodenum)
Produced by: the pancreas

40. 13.3 Enzyme: maltase
Location: small intestine
Produced by: small intestine
Function: Maltose + H2O  Glucose + Glucose

41. 14. Proteins 14.1 Enzyme: Pepsin (protease)
Produced by: gastric glands
Location: the stomach
Function: Protein + H2O Peptides
14.2 Enzyme: Trypsin (protease)
Produced by: the pancreas
Location: the duodenum (small intestine)

42. 14.3 Enzyme: Peptidases
Produced by: small intestine
Location: small intestine
Function: Peptides + H2O  Amino Acids

43. 15. fats 15.1 bile (not an enzyme) Produced by: the liver
Location: the duodenum
Function: break down fats into droplets physically
15.2 Enzyme: lipase
Location: the duodenum (small intestine)
Produced by: pancreas
Function: Fats + H2O  Glycerol + 3 fatty acids

44. Reference A lot of thanks to Mr. H’s notes!
A lot of thanks to Biology 12 textbook
Extra information (digestive problems and diseases)