Deck 16: B--The Digestive System

Question 1

Use this figure to answer the corresponding questions.
Number ____ identifies the ____________________, which secretes three proteolytic enzyme precursors. After activation, these precursors become three active enzymes including ____________________, ____________________, and ____________________.

Answer 1

6, pancreas, trypsin, chymotrypsin, carboxypeptidase

Question 2

Indicate the causes and effects of constipation and diarrhea.

Answer 2

Constipation occurs when feces remain in the colon for longer than normal periods, which causes more H₂O to be absorbed, making the feces hard and dry. Factors that could lead to constipation include: (1) ignoring the urge to defecate; (2) decreased colon motility resulting from aging, emotion, or a low-fiber diet; (3) obstruction of fecal movement caused by a local tumor or spasm; and (4) impairment of the defecation reflex, such as through injury of the nerve pathways involved. In some cases, constipation can allow hardened fecal material to become lodged in the appendix, causing it to become inflamed (appendicitis). This can lead to circulatory interference and if the appendix ruptures, the result is the spread of bacteria into the abdominal cavity.

Question 3

Describe the chemical digestion of proteins, including the sites where it occurs, specific enzymes involved and their actions, the sources of the enzymes, and how certain enzymes are activated.

Answer 3

Protein digestion begins in the stomach, which secretes pepsinogen that is activated into the active enzyme pepsin by the action of hydrochloric acid. Pepsin breaks proteins into peptide fragments. In the small intestine, enzymes from the pancreas break down peptide fragments into smaller peptides and amino acids. The pancreas secretes three enzyme precursors: trypsinogen, chymotrypsinogen, and procarboxypeptidase, all of which enter the small intestine where they are activated and then break up proteins and peptide fragments. Trypsinogen is first activated by the enzyme enterokinase in the brush border of the small intestine. Trypsin then converts chymotrypsinogen to chymotrypsin and procarboxypeptidase to carboxypeptidase. The small intestine synthesizes aminopeptidases and embeds them within cell membranes of the brush border. These enzymes break peptide fragments into amino acids or very small peptides. The small intestine's epithelial cells absorb the amino acids and small peptides. The small peptides are then broken down to amino acids by intracellular peptidases.

Question 4

Use this figure to answer the corresponding questions.
The hormone called secretin has a stimulatory effect on the ____________________ (labeled # ____) and the ____________________ (labeled # ____), but it has an inhibitory effect on the ____________________ (labeled # ____).

Question 5

Use this figure to answer the corresponding questions.
Match the following statements with all appropriate organ number(s). Some numbers may be used more than once.

Question 6

Describe the defecation reflex. Include the following in your

Question 7

Use this figure to answer the corresponding questions.
Number ____ identifies the ____________________, which utilizes SGLT and GLUT-5 carriers.

Question 8

Describe factors within the stomach and duodenum, and those outside the digestive system that affect gastric motility and emptying.

Question 9

Indicate which item in the top column best describes the item in the bottom column by writing the appropriate letter in the blank.

Question 10

Describe how food in the stomach affects other structures in the digestive system. Include information about hormonal and neural reflexes.