Concept Check Chapter 21 Silverthorn Questions:
1. Is the lumen of the digestive tract on the apical or basolateral side of the intestinal epithelium? On
the serosal or mucosal side?
2. Name the four layers of the GI tract wall, starting at the lumen and moving out.
3. Name the structures a piece of food passes through as it travels from mouth to anus
4. Define digestion. What is the difference between digestion and metabolism [p. 138]?
5. Why is the digestive system associated with the largest collection of lymphoid tissue in the body?
6. Draw a cell showing (1) an enzyme in a cytoplasmic secretory vesicle, (2) exocytosis of the vesicle,
and (3) the enzyme remaining bound to the surface membrane of the cell rather than floating
away.
7. What is the difference between absorption and secretion?
8. How do fats absorbed into the lymphatic system get into the general circulation for distribution to
cells? [Hint: p. 535]
9. Why are some sphincters of the digestive system tonically contracted?
10. Excitation of GI function by the parasympathetic division and inhibition by the sympathetic division
is an example of what kind of control?
11. How do mucin, amylase, and immunoglobulins move from salivary gland epithelial cells into the
lumen of the gland? (Hint: They are all proteins.)
12. Do bile salts digest triglycerides into monoglycerides and free fatty acids?
13. Bile acids are reabsorbed in the distal intestine by an apical sodium-dependent bile acid
transporter (ASBT) and a basolateral organic anion transporter (OAT). Draw one enterocyte. Label
the lumen, ECF, and basolateral and apical sides. Diagram bile acid reabsorption as described.
14. Explain how pH can be used to predict the location where a particular digestive enzyme might be
most active.
15. What activates pepsinogen, trypsinogen, and chymotrypsinogen?
16. In secretory diarrhea, epithelial cells in the intestinal villi may be damaged or may slough off. In
these cases, would it be better to use an oral rehydration solution containing glucose or one
containing sucrose? Explain your reasoning.
Concept Check Chapter 21 Answers:
1. The lumen is on the apical or mucosal side of the intestinal epithelium.
1. Is the lumen of the digestive tract on the apical or basolateral side of the intestinal epithelium? On
the serosal or mucosal side?
2. Name the four layers of the GI tract wall, starting at the lumen and moving out.
3. Name the structures a piece of food passes through as it travels from mouth to anus
4. Define digestion. What is the difference between digestion and metabolism [p. 138]?
5. Why is the digestive system associated with the largest collection of lymphoid tissue in the body?
6. Draw a cell showing (1) an enzyme in a cytoplasmic secretory vesicle, (2) exocytosis of the vesicle,
and (3) the enzyme remaining bound to the surface membrane of the cell rather than floating
away.
7. What is the difference between absorption and secretion?
8. How do fats absorbed into the lymphatic system get into the general circulation for distribution to
cells? [Hint: p. 535]
9. Why are some sphincters of the digestive system tonically contracted?
10. Excitation of GI function by the parasympathetic division and inhibition by the sympathetic division
is an example of what kind of control?
11. How do mucin, amylase, and immunoglobulins move from salivary gland epithelial cells into the
lumen of the gland? (Hint: They are all proteins.)
12. Do bile salts digest triglycerides into monoglycerides and free fatty acids?
13. Bile acids are reabsorbed in the distal intestine by an apical sodium-dependent bile acid
transporter (ASBT) and a basolateral organic anion transporter (OAT). Draw one enterocyte. Label
the lumen, ECF, and basolateral and apical sides. Diagram bile acid reabsorption as described.
14. Explain how pH can be used to predict the location where a particular digestive enzyme might be
most active.
15. What activates pepsinogen, trypsinogen, and chymotrypsinogen?
16. In secretory diarrhea, epithelial cells in the intestinal villi may be damaged or may slough off. In
these cases, would it be better to use an oral rehydration solution containing glucose or one
containing sucrose? Explain your reasoning.
Concept Check Chapter 21 Answers:
1. The lumen is on the apical or mucosal side of the intestinal epithelium.
