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We have learnt…

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. Question 1. What is the enzyme that is produced by the mouth? Protease Lipase Amylase Cellulase. Question 2.

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We have learnt…

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  1. 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

  2. Question 1 What is the enzyme that is produced by the mouth? • Protease • Lipase • Amylase • Cellulase

  3. Question 2 What is the process of moving food down the oesophagus • By gravity • Absorption • Excretion • Peristalsis

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

  5. Question 4 Which of the following is not one of the stages of holozoic nutrition? • Absorption • Egestion • Ingestion • Digestion

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

  7. The Stomach

  8. 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

  9. Stomach : Functions • Mechanical Digestion • Peristalsisin the stomach helps to mix and churn the food • Digestion of proteins. • Storageof food, where the partly digested food particles becomes liquefied chyme.

  10. Stomach : Functions 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

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

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

  13. Stomach : Functions Pepsin (protease) • Digest proteins into polypeptides proteins polypeptides pepsin Pepsin does not digest proteins to amino acids!

  14. Stomach : Functions • 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 Ca2+ • This allows the insoluble casein to remain in the stomach long enough for digestion by pepsin.

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

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

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

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

  19. Holiday Assignment • Ten Years Series Questions • Watch animation and complete the worksheet

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