Digestive+System+Review+NLL

Digestive System Review

1. Argue that absorption is the most important of the five processes of digestion over the other four processes. (144-45) Absorption occurs as unit molecules produced by digestion (i.e., nutrients) cross the wall of the GI tract and enter the cells lining the tract. From there, the nutrients enter the blood for delivery to cells. Without absorption humans wouldn’t be able to survive because there is no blood flow.

2. List the main organs of the digestive tract and state the contribution of each to the digestive process. (146-54) Mouth; teeth chew food, tongue tastes and pushes food for chewing and swallowing. Pharynx is the passageway where food is swallowed. Esophagus is the passageway where peristalsis pushes food to stomach. Stomach secretes acid and digestive enzyme for protein; churns; mixing food with secretions, and sends chyme to small intestine. Small intestine mixes chyme with digestive enzymes for final breakdown; absorbs nutrient molecules into body; secretes digestive hormones into blood. Large intestine absorbs water and salt to form feces. Rectum stores and regulates elimination of feces. Anus.

3. Name the enzymes involved in the digestion of starch, protein, and fat, and tell where these enzymes are active and what they do. (151) Salivary amylase→salivary glands→mouth→Starch+ H2O→maltose Pancreatic Amylase→pancreas→small intestine→strach+H2O→Maltose Maltase→small intestine→small intestine→maltose+H2O→glucose+ glucose Pepsin→gastric glands→stomach→protein+H2O→peptides Trypsin→pancreas→small intestine→ protein+H2O→peptides Peptidases→small intestine→small intestine→ peptide+H2O→ amino acids Lipase→pancreas→small intestine→Fat droplet+H2O→monoglycerides+fatty acids

4. Why are the pancreas, liver, and gall bladder considered accessory organs of digestion and not an organ of digestion? (152) Pancreas produces pancreatic juices; contains digestive enzymes, and sends it to the small intestine; produces salin and secretes it into the blood after eating. Liver is a major metabolic organ; processes and stores nutrients; produces bile for emulsification of fats. Gallbladder stores bile from liver; send it to the small intestine. Without the pancreas, live, and gall bladder humans couldn’t survive.

5. What is the chief contribution of each of these in the body--carbohydrates, proteins, and lipids (fats)? (158-59) Carbohydrates are essential to the body because the produce sugar (glucose). Glucose is a simple sugar preferred by the body as an energy source. It is necessary to include carbs in the diet because the body is unable to convert fatty acids to glucose. Proteins are needed to supply the essential amino acids. Lipids have several functions of the body; it is used for long-term energy storage, it insulates against heat loss, and it forms a protective cushion around major organs.

9. D 10. A 11. B 12. E 13. C 14. A 15. B 16. E 17. D 18. D 19. D 20. E 21. C 22. E 23. B 24. C 25. D 26. A 27. A 28. B 29. C