1. The Digestive System

2. Objectives To learn the definition of Digestive system
To know the various organs involved in the digestion process
To know the functions of the various organs of digestive system
To know the types of the digestion
To know various phases of the digestion

4. Definition
The digestive system is the system which process the complex food and converts it into absorbable form by all body cells.
Functions
Ingestion (To take the food in the mouth)
Secretion (To secrete the saliva i.e. water and enzyme)
Mixing and Propulsion(Mixing with enzyme and liquid)
Digestion (chemical and mechanical)
Absorbtion (To make the food in the absorbable form)
Defecation (to remove the waste and metabolic by product from the body)

5. Digestive System Organization
Gastrointestinal (Gl) tract (Alimentary canal)
Accessory Organs
Structures
Mouth
Esophagus
Stomach
Small intestine
Large intestine

6. Various organs and their role
Mouth
Breaks down food into small pieces
Begins starch digestion (amylase)
Saliva produces amylase and lubricates food
Moves food into esophagus
Peristalsis moves food to stomach

7. Various organs and their role
Esophagus
Usually collapsed (closed)
Surrounded by
Blood vessels
Functions
Secrete mucous
Transport food

8. Stomach Usually “J” shaped Left side, anterior to the spleen
Mucous membrane
Functions
Mix food
Reservoir
Start digestion of
Protein
Nucleic acids
Fats
Activates some enzymes
Destroy some bacteria
Makes intrinsic factor

9. Small Intestine Extends from pyloric sphincter  ileocecal valve
Regions
Duodenum
Jejenum
Ileum
Movements
Segmentation
Peristalsis

10. Small Intestine Absorbs Lipids Monoglycerides Fatty acids Micelles
80% ingested water
Electrolytes
Vitamins
Minerals
Carbonates
Active/facilitated transport
Monosaccharides
Proteins
Di-/tripeptides
Amino acids
Lipids
Monoglycerides
Fatty acids
Micelles
Chylomicrons

11. Large Intestine

12. Functions Absorbs Mechanical digestion Concentrate/eliminate wastes
Haustral churning
Peristalsis
Reflexes
Gastroileal
Gastrocolic
Chemical digestion – Bacterial digestion
Ferment carbohydrates
Protein/amino acid breakdown
Absorbs
More water
Vitamins B K
Concentrate/eliminate wastes

13. Feces Formation and Defecation
Chyme dehydrated to form feces
Feces composition
Water
Inorganic salts
Epithelial cells
Bacteria
Byproducts of digestion
Defecation
Peristalsis pushes feces into rectum
Rectal walls stretch

14. Accessory Organs Teeth Tongue Salivary glands Pancreas Liver
Gall bladder

16. Digestion Types Mechanical (physical) Chew Tear Grind Mash Mix
Chemical
Catabolic reactions
Enzymatic hydrolysis

17. Phases
Ingestion
Secretion
Mixing and propulsion
Digestion
Absorption
Defecation
Visual presentation:

18. SUMMARY LIST THE ORGANS INVOLVED IN THE G I TRACT
LIST THE ACCESSORY ORGANS
LIST THE TYPES OF THE DIGESTION
LIST THE MAIN PHASES INVOLVED IN DIGESTION PROCESS