2. Unit 3: Animal Anatomy & Physiology The Digestive System

3. Digestive System responsible for 4 major functions: 1.ingestion intake of nutrients (eating) 2.digestion the breakdown of food into small soluble molecules a) physical digestion: (ex.) chewing – mechanical digestion that cuts food into small pieces – smaller pieces increase surface area for enzymes to work on

4. Digestive System 4 major functions (continued): b) chemical digestion: ex. digestive secretions (saliva) enzymes in digestive juices chemically breakdown food molecules into their monomers (soluble) monomersfood

5. Digestive System b) chemical digestion: (continued) i) carbohydrates i.e. polysaccharides & disaccharides monosaccharides

6. Digestive System b) chemical digestion (continued): ii) proteins amino acids

7. Digestive System b) chemical digestion (continued): iii) lipids

8. Digestive System 4 major functions (continued): 3.absorption the uptake of nutrient molecules, first into the cells of the small intestine then into the blood stream 4.Egestion: removal of solid undigested material (feces) from anus  eating cellulose (fiber) helps ** Excretion (part of the excretory system) removal of liquid soluble waste (urine) from the bladder via urethra

9. Components of the Digestive System Mouth Esophagus Stomach Small Intestine Large Intestine Rectum Anus Liver Pancreas Gall Bladder digestive tract (alimentary canal) really just a very long tube (~ 9 m long) takes food ~ 24 - 33 hours to go through digestive tract

10. Components of the Digestive System OrganCommentsFunction 1.Mouth opening to digestive system a)Teethdifferent shapes for tearing & grinding ingestion physical digestion

11. Mouth (Oral Cavity)

12. Components of the Digestive System Teeth: Molars (12) Premolars or bicuspids(8) Canines (4) Incisors (8)

13. Anatomy of the Mouth

14. Components of the Digestive System OrganCommentsFunction b) saliva made by 3 pairs of salivary glands secrete saliva into oral cavity contains: 1.water: 2.mucus: 3.salivary amylase: lubricates food (makes it slippery) help to dissolve food enzyme which digests starch i.e. into mono & disaccharides Parotid gland Submandibular gland Sublingual gland

16. Salivary GlandsSublingual gland Parotid gland Submandibular gland Tongue Mouth (oral cavity)

17. Components of the Digestive System OrganCommentsFunction c) tongue very strong muscle contains large numbers of taste buds bolus: 2. physical digestion: chewing & mixing food with saliva 1.sensory: taste & temperature control 3. swallowing: a.pushes bolus up & to the back of the throat nerve endings. ball of chewed food b.causes epiglottis to block windpipe 4. speech

18. Components of the Digestive System Tongue: Different parts of the tongue are able to taste one of four basic tastes. sour bitter salty sweet

19. NOT IN YOUR NOTES Components of the Digestive System OrganCommentsFunction d) epiglottis 2) pharynx flap of tissue at the base of the tongue above the trachea back of the throat prevents food from going into lungs (down trachea) to avoid choking. common passageway for food & air

20. Components of the Digestive System OrganCommentsFunction 3) esophagus narrow tube about 24 cm long connecting pharynx to stomach contains 2 muscle layers which relax and contract rhythmically for peristalsis. 1. leads food into stomach 2. ensures that food (bolus) is pushed into stomach (mucus glands help lubricate the bolus) wave-like contractions

21. Esophagus (24 cm long, carries food) Lined with circular and longitudinal muscle Lower end of esophagus is thickened just before stomach (sphincter) (ie: heartburn) Regurgitation – movement of food from the stomach up the esophagus and out the mouth

22. SWALLOWING

23. Stomach Esophagus Pharynx

24. Stomach

25. Glands: – Located in lining of stomach – Produce gastric juices which contain: (i) HCl – Chemical breakdown of fibrous tissue Kills bacteria (ii) Pepsin – Enzyme which breaks down proteins (iii) Mucus –Thick layer which protects stomach wall from acid and pepsin

26. Sphincters: Small ring like muscles located at either end of the stomach (i) Cardiac Sphincter – Controls entry of food into stomach from esophagus Closed during digestion to avoid re-entry into esophagus (heart burn) (ii) Pyloric Sphincter – Controls entry of chyme (partially digested food & gastric juices) into the small intestine

27. Components of the Digestive System cardiac sphincter pyloric sphincter duodenum circular muscles oblique muscles longitudinal muscles

28. Components of the Digestive System glands in stomach lining ulcer in stomach lining

29. ENDOSCOPE ACID REFLUX GASTRIC FOLDSSTOMACH LINING & GASTRIC JUICE

30. ENDOSCOPE STOMACH ULCER MULTIPLE STOMACH ULCERS

31. Before food enters the small intestine: It must pass through the PYLORIC SPHINCTER which is a valve that contracts and relaxes to control the flow of food leaving the stomach and going to the small intestine.

34. Extra info in the next slides!

35. Components of the Digestive System Kinds of TeethDescriptionFunction  long & pointy  sharp  rip/tear  very developed in predators  wide, but very thin  bumps on bottom edges  cut like knives for biting  flat & broad  have 2 bumps on surfaces called cusps (bicuspids)  grinding & mashing  flat & broad  have 4 cusps  grinding & mashing Canines Incisors Premolars Molars

36. Components of the Digestive System periodontal membrane enamel pulp (cavity) root canal nerve artery vein dentin crown (above gums) gingiva (gums) root (under gums) nerve endings

37. Salivary Glands Parotid Gland (below/ in front of ears, largest) Sublingual Gland (floor of mouth, smallest) Submandibular Gland (below and behind sublingual)

38. Ducts and Saliva Ducts – tubular canals for carrying glandular secretions from one part of the body to another. Saliva – Moisten and lubricate food – First step in chemical digestion