Hormones of the
Digestive System

Hormone Basics
 Hormones are secreted into the blood stream and must circulate
the body before reaching target location
 Hormones turn things on (stimulate) or off (inhibit)
 Hormones are regulated by hypothalamus in the brain
 Endocrine glands are gland that secrete hormones

GASTRIN:
Secretion: By “G cells” of stomach lining
Stimulus: Stomach distention and acid pH of chyme
causes gastrin to be produced.
Action:
 1. increases HCl production in stomach
 2. increases gastric motility
 3. stimulates growth of gastric mucosa
 4. contract lower esophageal sphincter
 5. relaxes pyloric sphincter
 6. relaxes ileocecal sphincter

SECRETIN:
Secretion: By (S) cells in the small intestine.
Stimulus: Acid chyme in small intestine causes
secretion of secretin
Actions:
 stimulate secretion of pancreatic juice and bile that is rich in
bicarbonate ions.
 inhibit production of HCl in stomach
 promote growth and maintenance of the pancreas
 enhance effects of Cholecystokinin (CCK)
 Increases rate of bile secretion by liver

CHOLECYSTOKININ (CCK):
Secretion: Enteroendocrine cells in the small
intestine mucosa (Crypts of Lieberkuhn)
Stimulus: Chyme rich in amino acids, triglycerides
and fatty acids enter the small intestine.
Actions:
 increases secretion of pancreatic juice rich in digestive
enzymes
 opens the Sphincter of Oddi (from common bile duct)
 contracts the gallbladder
 Inhibits gastric secretion and motility
 May reduce hunger

Gastric Inhibitory Peptide (GIP):
Secretion: Enteroendocrine cells in the small intestine
Stimulus: Chyme rich in glucose enter the small
intestine.
Actions:
 Stimulates release of insulin by beta cells of pancreas
 Inhibits gastric secretion and motility
 Stimulates glucose use by skeletal muscle cells

Hormonal control in the Digestive system
Pancreas and Islets of Langerhans
 Endocrine cells make up 1% of the pancreas and are
observed as Islets of Langerhans:
1. Alpha Cells: Secrete Glucagon (increases blood
sugar)
2. Beta Cells: Secrete Insulin (decreases blood sugar)
3. Delta Cells: Secrete Human Growth Hormone- Inhibiting
Hormone (inhibit secretion of both glucagon and insulin
and slows rate of nutrient absorption)
4. F-Cells: Secrete Pancreatic Polypeptide (inhibit
secretion of digestive enzymes and inhibits contraction
of the gallbladder)

Hunger Hormones
 Hunger – a feeling of discomfort or
weakness caused by a lack of food
 Satiety – a feeling of fullness

Hunger Hormones

Hunger Hormones
Case Study
 Work as a table team to
answer the questions in
the case study
 What are some of the
issues that are occurring
in his body? How might
his digestive organs be
involved?

Case Study
What is the difference between type 1 and type 2
diabetes?

Case Study
Flow Chart

Case Study
Flow Chart