1. Unit 2A Human Form & Function Body systems The digestive system

2. Study Guide Read: Text page 87- 98 Complete: RQ 5-13 AYK 1-8

3. Digestion  Digestive processes can be chemical (involving digestive enzymes), or mechanical.  Chemical digestion the breaking down of the nutrients we eat into simpler organic compounds that can be absorbed by the body.  Mechanical digestion is the breaking down of large sized food to smaller sized food.

4. ENZYMEActs onEnd product AmylaseCarbo- hydrate Simple sugars (e.g. glucose) LipaseLipidsFatty acids ProteaseProteinsAmino acids

5. The anatomy of the digestive system US Govt NIH

6. Structure of the alimentary tube Mucosa Longitudinal muscle layer Circular muscle layer Peritoneum Villus Submucosa Thin muscle layer

7. Chemical digestion in the mouth EnzymeProduct Salivary amylase Polysaccharides → Sugars

8. The salivary glands Parotid gland Submandibular gland Sublingual gland

9. Section through the head Nasal cavity Palate Tongue Pharynx Hyoid bone Epiglottis Larynx Esophagus Teeth Vocal cords The Miles Kelly Art library, Wellcome Images

10. The tongue Jari Keinänen

11. Mechanical processes in the mouth  Chewing (mastication)  Bolus formation  Swallowing

12. Human teeth are generalised – they can process both meat and fibrous plant foods The Miles Kelly Art library, Wellcome Images Incisor teeth Premolar and molar teeth Canine tooth

13. Human dentition Molars Pre-molars Canine Incisors Gray’s Anatomy

14. Tooth section Enamel Dentine Pulp cavity Cementum Gum Root canal Crown Neck Root The Miles Kelly Art library, Wellcome Images

15. Swallowing and peristalsis The Miles Kelly Art library, Wellcome Images Epiglottis closes entrance to windpipe Tongue pushes bolus into throat Peristalsis carries bolus into stomach

16. Peristalsis Wave-like contraction of the muscular wall travels along the gut BOLUS

17. Chemical digestion in the stomach EnzymeProduct Hydrochloric acid Activates pepsinogen ( → pepsin) PepsinProteins → peptones

18. Mechanical processes in the stomach  Muscular churning mixes food with gastric juices (forms chyme)  Rennin (in infants only) curdles milk

19. Absorption in the stomach  Limited absorption of water, glucose, alcohol and some drugs takes place in the stomach.

20. Section through the stomach Esophagus Fundus Rugae Pyloric sphincter muscle G Meyer ANHB – UWA

21. Section through the stomach Esophagus Rugae Pyloric sphincter muscle Three muscle layers Duodenum

22. Chemical digestion in the duodenum EnzymeProduct AmylasesDisaccharides → glucose LipaseFats & oils → fatty acids + glycerol TrypsinPeptones → polypeptides

23. Mechanical processes in the duodenum  Bile salts emulsify fats (reduce them to small droplets which increases their surface area).

24. Inside the duodenum

25. Chemical digestion in the small intestine EnzymeProduct Maltase Lactase Sucrase Maltose → glucose Lactose → glucose Sucrose → glucose LipaseFats & oils → fatty acids & glycerol PeptidasesPolypeptides → amino acids

26. Absorption in the small intestine Glucose, amino acids, water and minerals are absorbed into the blood capillaries. Fatty acids and glycerol are absorbed into the lacteals (forming chyle).

27. Section through small intestine showing villi L. Slomianka ANHB-UWA Secretory cells Villus Gland

28. Section through a villus Lacteal Network of blood capillaries Epithelial cells & goblet cells Lymph vessels Intestinal gland

29. Functions of the large intestine Further absorption of water and some salts. Bacterial activity – there are trillions of resident bacteria in the large intestine. They are believed to have several important roles in addition to digesting cellulose in plant foods and synthesising some vitamins (e.g. folic acid).

30. The large intestine Caecum Appendix Colon (ascending branch) Colon (transverse branch) Colon (descending branch) Rectum LIVER

31. Some major functions of the liver  Deaminates amino acids  Converts glucose to glycogen  Produces bile  Stores iron, and vitamins A, B 12, D, E & K  Synthesises vitamin A & plasma proteins  Detoxifies drugs (including alcohol) and other toxins.

32. Wellcome Photo Library Liver Stomach Pancreas

33. External features of the liver Miles Kelly Art Library Gall bladder Bile duct Hepatic artery Hepatic portal vein Inferior vena cava

34. Liver lobule Artery, vein & bile duct Central vein Lobule L. Slomianka ANHB-UWA