Introduction to the Digestive System

1. Introduction to theDigestive System

2. Explain why digestion of large food molecules is essential • breaking down of food particles into forms small enough to be utilized by body cells – monomers!!!!! • Includes: - mechanical digestion (mastication) Explain the need for enzymes in digestion: - chemical digestion (enzymatically driven….reduces large nutrients to their monomers!!!!!!)

3. Digestive Process • ingestion - taking food into the mouth • movement - passage of food through the gastrointestinal tract • digestion - mechanical and chemical breaking down of food • absorption - passage of digested food into the blood and lymph • assimiliation – when nutrients become part of the tissues of the body • egestion- elimination of indigestible substances and undigested

4. Mouth:Mechanical and Chemical Digestion

5. Physiology of Digestion – Explain the need for enzymes in digestion

6. State the source, substrate, products and optimum pH conditions for one lipase, amylase and protease Source Substrate Products pH • amylase – Protease – lipase –

7. Draw and label a diagram of the digestive system

9. Outline the function of the stomach

10. Functions of the Stomach: • Mechanical Digestion • Churning • Hydrochloric acid (parietal cells) • Chemical Digestion • Pepsin from zymogen…Pepsinogen (chief cells) • Breaks peptide bonds between specific amino acids only • End product: smaller polypeptides in Chyme

11. Outline the functions of the small and large intestine • In the small intestine, enzymes complete the process of digestion where the end matter – monomers of protein, lipids, carbohydrates and nucleic acids is absorbed by villi. • The large intestine absorbs water and passes the unabsorbable rest off as feces.

12. Distinguish between absorption and assimilation • absorption - passage of digested food into the blood and lymph • assimiliation – when nutrients become part of the tissues of the body

13. Outline the relationship b/w structure and function of the villi of the sm. intestine • Increase s.a. • One layer of epithelial cells facilitates quick absorption • Microvilli – plasma membrane extensions • IMP channels – for fac. diff. - act. Trans. • Mitochondria in epithelial cell - - ATP needed for act. Trans. • Blood capillaries inside villi - - close to epithelial cells = quick absorption • Lacteal of lymphatic system present for fat transport

15. Absorption: Villus & epithelial cells; microvilli