12.3.2 The Beginning of Chemical Digestion Flashcards Preview

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Flashcards in 12.3.2 The Beginning of Chemical Digestion Deck (11)
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1
Q

The Beginning of Chemical Digestion

A
  • A major goal of the digestive system is to break down macromolecules into smaller subunits using chemicals.
  • Salivary glands in the mouth produce salivary amylase, which breaks down starches into smaller polysaccharides.
  • Secreted in by parietal cells in the stomach wall, hydrochloric acid functions by disrupting the extracellular matrix of tissues and killing bacteria.
  • Chief cells in the stomach wall secrete pepsinogen. Pepsinogen is converted by HCl into its active form, pepsin. Pepsin breaks down proteins into small polypeptides.
2
Q

mouth

A
  • Food begins to be broken down in the mouth. Salivary glands in the mouth produce saliva, which contains
    salivary amylase. Salivary amylase is an enzyme that breaks down starch and glycogen into smaller polysaccharides.
3
Q

stomach

A
  • Swallowed food enters the stomach. Parietal cells found within the gastric pits in the lining of the stomach secrete gastric juice. The hydrochloric acid present in gastric juice functions as a defense mechanism by killing bacteria present in food that is ingested. Hydrochloric acid also disrupts the extracellular matrix present in tissues, aiding in the breakdown of foods.
4
Q

gastric pit

A
  • Chief cells, also present in the gastric pits of the stomach lining, secrete pepsinogen. Pepsinogen is the inactive form of the enzyme pepsin. Hydrochloric acid secreted by parietal cells converts pepsinogen into pepsin. In addition to being activated by hydrochloric acid, pepsinogen can also be activated by pepsin. Active pepsin is able to break down proteins into smaller polypeptides.
5
Q

Pepsin is an enzyme that catalyzes the breakdown of proteins into smaller polypeptides. Which of the following react to form pepsin?

i. hydrochloric acid (HCl) secreted by chief cells
ii. hydrochloric acid (HCl) secreted by parietal cells
iii. pepsinogen secreted by the chief cells
iv. pepsinogen secreted by parietal cells

A
  • ii, iii
6
Q

As proteins travel through the digestive system, they:

A
  • are broken down into amino acids.
7
Q

Proteins in the stomach are broken down into smaller polypeptides and dipeptides by the action of

A
  • pepsin
8
Q

Why is it an important adaptation for chief cells to produce pepsinogen, a precursor to pepsin, rather than directly producing pepsin?

A
  • Pepsin would destroy chief cells by digesting internal proteins.
9
Q

Which of the following is not a role of the HCl secreted by the parietal cells?

A
  • disruption of the intracellular matrix of tissues
10
Q

Which of the following statements about the stomach is false?

A
  • The stomach has an extremely high pH
11
Q

Salivary amylase is secreted by the salivary glands, and catalyzes

A
  • the breakdown of starch and glycogen to smaller polysaccharides.

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