2. 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
3.
4. 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
5.
6. 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
7.
8. 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
9.
10. 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
11.
12. 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)
13.
14.
15.
16. Hunger Hormones
Hunger – a feeling of discomfort or
weakness caused by a lack of food
Satiety – a feeling of fullness
19. 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?
