2. We have learnt… What are the 4 stages of nutrition? Why must we digest our food? What are the two types of digestion? What is the structure and function of: – Mouth – Oesophagus

4. Question 1 What is the enzyme that is produced by the mouth? (A)Protease (B)Lipase (C)Amylase (D)Cellulase

5. Question 2 What is the process of moving food down the oesophagus (A)By gravity (B)Absorption (C)Excretion (D)Peristalsis

6. Question 3 Digestion is present in the oesophagus. True/False

7. Question 4 Which of the following is not one of the stages of holozoic nutrition? (A)Absorption (B)Egestion (C)Ingestion (D)Digestion

8. Lesson Objective Describe the structure and the main functions of the stomach in relation to digestion. Holiday Assignment

9. The Stomach

10. Stomach : Structure Thick muscular bag with thick muscle walls At the end of the stomach, there is a muscular valve called pyloric sphincter Controls the entry of food from the stomach into the intestines

11. Mechanical Digestion Peristalsis in the stomach helps to mix and churn the food Digestion of proteins. Storage of food, where the partly digested food particles becomes liquefied chyme. Stomach : Functions

12. Protein digestion begins in the stomach Proteins  polypeptides Protein digestion in the stomach requires the gastric juice Food in the stomach stimulates the gastric glands to secrete gastric juice

13. Gastric Juice Gastric juice is a dilute solution of: –Hydrochloric acid (~pH 2) –Pepsin –Rennin Gastric Juice

14. Functions of dilute HCl: Denatures salivary amylase Activates inactive enzyme, Pepsin Provide slightly acidic for action of gastric enzymes Kills potentially harmful microorganisms Stomach : Functions

15. Pepsin (protease) Digest proteins into polypeptides proteins polypeptides pepsin Pepsin does not digest proteins to amino acids!

16. Function of Rennin (for your information): Rennin curdles milk proteins –converts the soluble caseinogen found in milk to insoluble casein –caseinogen (soluble) casein (insoluble) –this process requires Ca 2+ This allows the insoluble casein to remain in the stomach long enough for digestion by pepsin. Stomach : Functions

17. Summary Stomach –Structure –Functions Mechanical Digestion Chemical Digestion Hydrochloric acid (~pH 2) Pepsin Rennin

18. Remember your job application? Let us assess without you will get the job!

19. Mouth Applying for job : Digestion of Starch Condition: pH 7 Skills: Tongue Teeth Saliva

20. Stomach Applying for job: Digestion of protein Condition: pH2 Skills: Mechanical Digestion Chemical Digestion (Gastric Juice) Hydrochloric acid Pepsin Rennin

21. Holiday Assignment 1.Ten Years Series Questions 2.Watch animation and complete the worksheet