1. The Human Digestive System

2. Cells, Tissues, Organs & Systems
The basic structure in the human body is the CELL
There are over 200 different types of cells in the human body
Cells of the same type combine to form TISSUES
Different tissues combine to form organs (structures that work towards a common goal)

3. Cells, Tissues, Organs & Systems
Groups of organs working together towards a common goal are called SYSTEMS

4. The Digestive System

5. Digestion
The transformation of food into smaller molecules that can be used by the body
Two ways:
Physical Transformation: breaking food down physically and moving it along through the tube
Chemical Transformation: enzymes produced by the body break apart different molecules

6. Anatomy of the Digestive System
Digestive Tract
Mouth
Esophagus
Stomach
Small Intestine
Large Intestine (Colon)

7. Anatomy of the Digestive System
Digestive Glands
Salivary glands
Pancreas
Liver
Gastric glands
Intestinal glands

8. The Mouth

9. The Mouth The Tongue Teeth
Responsible for moving food around to different parts of the mouth
Teeth
Incisors: four front teeth (top & bottom); used to cut pieces of food
Canines: pointy teeth beside incisors; used to shred food (especially meat)
Premolars: towards the back from canines; used to grind and crush food
Molars: at the very back; used to grind and crush food

10. The Mouth

11. The Mouth The Pharynx (throat) Salivary glands
Cavity at the back of the mouth
Place where digestive and respiratory tubes meet
Salivary glands
Produce saliva
Saliva is used to kill bacteria and begin the digestion of starch molecules
Three sets: parotid glands, sublingual glands and submandibular glands

12. The Mouth

13. The Esophagus A tube, roughly 25 cm long and 3 cm in diameter
Peristaltic contractions of the walls of the esophagus push food down to the stomach

14. The Esophagus

15. The Stomach The stomach has valves at both ends
The cardiac sphincter (entrance)
The pyloric sphincter (exit)
The gastric glands produce gastric juice (a mix of enzymes, hydrochloric acid and mucus)
Function: mixes food with gastric juice to begin digesting protein and sugars

16. The Stomach

17. The Small Intestine About 7 m long and 3 cm in diameter Three sections
The Duodenum: first 25 cm at the exit of the stomach
The Jejunum: next 2 m
The Ileum: the final 5 m ending at the colon
Intestinal Glands: produce intestinal juice (a mix of enzymes used to digest protein and carbohydrates)

18. The Small Intestine

19. The Liver The largest gland of the human body
Produces BILE, a liquid that is stored in the GALL BLADDER
Bile drains down to the duodenum when needed and is used to break fats into smaller droplets

20. The Liver

21. The Pancreas A long, leaf-shaped gland below and behind the stomach
Produces PANCREATIC JUICE, a liquid that drains to the duodenum and is used to digest protein
Also produces INSULIN, a hormone used to help sugars leave the blood and enter cells

22. The Pancreas

23. Absorption
At the end of the digestive process (in the small intestine), simple nutrients are ready to enter the bloodstream
Carbohydrates: simple sugars (glucose, galactose and fructose)
Protein: amino acids
Fat: fatty acids and glycerol
Vitamins
Minerals

24. Absorption
Simple nutrients pass through VILLA in the walls of the small intestine

25. The Large Intestine (Colon)
About 2 m long and 8 cm in diameter
Begins with the cecum and the appendix
Ends with the rectum and the anus
Divided into three sections:
Ascending colon
Transverse colon
Descending colon

26. The Large Intestine (Colon)
Water is absorbed into the blood
Some vitamins are produced by bacteria living in the colon and then absorbed

27. The Large Intestine (Colon)

28. All together now…