Enzymes, Chemicals and Hormones associated with the Human Digestive System
MOUTH
Enzyme, Chemical,
Hormone or Cell
Enzyme,
Chemical,
Hormone
or Cell
Important Information
Salivary Amylase
enzyme
Found in saliva that catalyzes the hydrolysis (breaking down) of starch, glycogen and
related polysaccharides into more simple and readily usable forms of sugar.
Ptyalin
enzyme
A form of amylase found in the saliva of humans and some other animals; converts starch into
simple soluble sugar
Betaine
Chemical
Maintains cell fluid balance as osmolytes (dehydration, dry mouth); protects cells, proteins, and
enzymes from environmental stress (eg, low water, high salinity, or extreme temperature)
Bromelain
enzyme
Found in pineapple, that breaks down protein and is used as a meat tenderizer; Anti-inflammatory
agent
Lysozyme
enzyme
Found in saliva (and tears) and catalyzes the destruction of the cell walls of certain bacteria.
STOMACH
Enzyme, Chemical,
Hormone or Cell
Parietal Cells
Enzyme,
Chemical,
Hormone
or Cell
cell
Chief Cells
cell
Mucous neck or Pit Cells
cell
Involved in mucous production and are replaced every 2–4 days. This high rate of turnover is a
protective mechanism designed to protect the epithelial lining of the stomach from both the action
of pepsin and the acid produced by parietal cells;
G Cells
cell
A gastrin-producing cell found in the antrum (initial portion of the pyloric portion of the stomach)
of the stomach and to a lesser extent in the mucosa of the duodenum
Pepsin
enzyme R Released in the stomach as pepsinogen (zymogen - an inactive substance that is converted into an
en enzyme when activated by another enzyme); the release of HCl stimulates the release of the basic
m form of pepsin; when pepsinogen is exposed to HCl in the stomach the pepsinogen unfolds and
pe breaks into pepsin; breaks down proteins into smaller polypeptides
chemical ThThe pH of gastric (stomach) acid should normally be between 1.5-3.5, HCl denatures proteins;
Aactivates the conversion of pepsinogen to pepsin; acts as antiseptic in the stomach; allows for
improper mineral absorption as it assists in ionizing minerals
HCl
Important Information
Are the stomach epithelium cells which secrete gastric acid (HCl); Primarily secreted in response
to ingested protein or fat; stress also may stimulate acid output; also secrete intrinsic factor
absorption of vitamin B12 and the normal development of red blood cells Pernicious anemia may
be caused by the absence of intrinsic factor.
Also called zymogenic cell. Any one of the columnar epithelial cells or the cuboidal epithelial cells
that line the gastric glands and secrete pepsinogen which are needed for the digestion of proteins
Intrinsic Factor
Chemical A A substance secreted by the stomach that enables the body to absorb vitamin B12. It is a
glycoprotein
fd glycoprotein
Gastrin
hormone
Gastrin is a major physiological regulator of gastric acid secretion. It also has an important growthpromoting influence on the gastric mucosa. Gastrin is synthesized in G cells, which are located in
gastric pits, primarily in the antrum region of the stomach. Anticipation of food, stomach
stretching (rugae), presence of partially digested food – stimulates the secretion of gastric juices
rich in pepsin and HCl which aid in digestion.