The Digestive
System:
Secretion of
Digestive Juices
By Yoshi (Erin) and
Mads (Maddie)
Salivary Glands

Salivary glands secrete saliva.

This saliva contains amylase, an enzyme
that turns starch into glucose.

Saliva serves in beginning the breakdown of
carbohydrates.

It also contains bicarbonate ions, which
neutralizes acids in the foods.
Gastric Glands

Located in the epithelial cells in the stomach, these gastric
glands secrete gastric juices.

Secretion of gastric juices is controlled by nervous (smells,
thoughts, caffeine) and endocrine signals.

The stomach secretes 400-800 mL of gastric juices per meal

The gastric juices contain HCL, which lowers the pH in the
stomach to between 1.5 and 2.5, thereby activating pepsin.

HCL also kills microorganisms which may be living in the
food.

Pepsin is released from the breakdown of pepsinogen which
serves as a stable storage for HCL and pepsin so that it is
not released when there is no food in the stomach.

Pepsin serves as an enzyme that begins protein digestion in
the stomach, and it works by splitting off fragments of
peptides from protein molecules during digestion in the
stomach.
Pancreatic Glands

Pancreatic juice is secreted into the small
intestine at the duodenum.

The pancreatic juice neutralizes the chyme,
using sodium bicarbonate, an acid
neutralizer.

The juice contains digestive enzymes:
•
Pancreatic amylase, which hydrolyzes
starch
•
Pancreatic lipase, which hydrolyzes
ingested fats
Small Intestine

The villi in the small intestine have cells that
produce enzymes which complete the
digestion of both peptides (protein) and
sugars (carbohydrates)