Digestive System
1. What is digestion?
2. How different are extracellular and intracellular digestion? What is the evolutionary advantage of extracellular digestion?
3. How is extracellular digestion related to tissue and cellular specialization?
4. What is the difference between an incomplete digestive and a complete digestive system system? How are these types of digestive tubes associated or not to extracellular digestion?
5. What are some evolutionary advantages of animals with complete digestive tube?
6. What is mechanical digestion? In molluscs, earthworms, arthropods, birds and vertebrates, in general, which organs respectively participate in this type of digestion?
7. Concerning extracellular digestion what is meant by chemical digestion?
8. Which kind of chemical reaction is the breaking of macromolecules into smaller ones that occurs in digestion? What are the enzymes that participate in this process called?
9. Which organs of the body is part of the human digestive system?
10. What are peristaltic movements? What is their role in human digestion?
11. From the lumen to the external surface what are the tissues that form the digestive tube wall?
12. What is the location of the salivary glands in humans?
13. What is the approximate pH of the salivary secretion? Is it an acid or basic fluid? What are the main functions of saliva?
14. What is the salivary digestive enzyme? Which type of food does it digest and into which smaller molecules does it transform the food?
15. Why doesn't the food enter the trachea instead of going to the esophagus?
16. Is the esophagus a muscular organ? Why even in a patient lying totally flat on a hospital bed can the swallowed food reach the stomach?
17. What is the route of the ingested food from swallowing until the duodenum?
18. What is the valve that separates the stomach from the esophagus called? What is its function?
19. What is the valve that separates the duodenum from the stomach called? What is its function?
20. What is the pH inside the stomach? Why is there a need to keep that pH level? How is it maintained? Which are the cells that produce that pH?
21. Besides being fundamental for the activation of the main gastric digestive enzyme how does HCl also directly participate in digestion?
22. How is the gastric mucosa protected from the acid pH of the stomach?
23. What is the digestive enzyme that acts within the stomach? Which type of food does it digest? What are the cells that produce that enzyme?
24. What name does the food bolus that passes from the stomach to the duodenum get?
25. Which are the three parts of the small intestine?
26. By generally dividing food into carbohydrates, fats and proteins and considering the digestive process until the pylorus (exit of stomach), which of these mentioned kind of food have already undergone chemical digestion?
27. What is the substance produced in the liver that acts in the small intestine during digestion? How does that substance act in the digestive process?
28. What is the adnexal organ of the digestive system in which bile is stored? How does this organ react to the ingestion of fat rich food?
29. What are the digestive functions of the liver?
30. Besides the liver which is the other adnexal gland of the digestive system that releases substances in the duodenum participating in extracellular digestion?
31. How does the pancreatic juice participate in the digestion of proteins? What are the involved enzymes?
32. How does the pancreatic juice resume the digestion of carbohydrates? What is the involved enzyme?
33. How does the pancreatic juice help the digestion of lipids? What is the involved enzyme?
34. Besides the pancreatic juice in the intestine there is the releasing of the enteric juice that contains digestive enzymes too. What are these enzymes and which type of molecule do each of these enzymes break?
35. Coming from the acid pH of the stomach which pH level does the chyme find when it enters the duodenum? Why is it necessary to maintain that pH level in the small intestine? What are the organs responsible for that pH level and how is it kept?
36. What are the five human digestive secretions? Which of them is the only one that does not contain digestive enzymes?
37. Why do protease-supplying cells of the stomach and of the pancreas make only precursors of the active proteolytic enzymes?
38. After digestion the next step is absorption done by cells of the mucous membrane of the intestine. For this task a large absorption surface is an advantage. How is it possible in the small internal space of the body of a pluricellular organism to present a large intestinal surface?
39. In which part of the digestive tube is water is chiefly absorbed? What about the mineral ions and vitamins?
40. From the intestinal lumen through to the tissues - what is the route of nutrients after digestion?
41. What is the special route that lipids follow during digestion? What are chylomicrons?
42. What are the so-called "good" and "bad" cholesterol? 43. Why does the ingestion of vegetable fibers improve the bowel habit in people that suffer from hard stools?
44. What are the major functions of the bacterial flora within the human gut?
45. The releasing of digestive secretions is controlled by hormones. What are the hormones that participate in this regulation?
46. How is it produced and what is the function of gastrin in the digestive process?
47. Where is it produced and what is the function of secretin in the digestive process?
48. How is it produced and what is the function of cholecystokin in the digestive process?
49. Where is it produced and what is the function of enterogastrone in the digestive process?
50. What are the special structures of the avian digestive tube and their respective functions?
51. Compared to mammals do birds absorb more or less water in their digestive system? Why is this phenomenon an adaptation to flight?
52. What is meant by "mutualist exploration of cellulose digestion", a phenomenon that occurs in some mammals and insects?
53. Cows swallow their food once and then this food goes back to the mouth to be chewed again. How can this phenomenon be explained?