The Digestive System

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

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)

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

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

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

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

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

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

Large Intestine

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

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

Accessory Organs Teeth Tongue Salivary glands Pancreas Liver Gall bladder

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

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

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