High School
SAT
ACT
University
MCAT
LSAT
DAT
Wize University Physiology Textbook > Gastrointestinal Physiology

Endocrine Glands of the GI Tract

GI TractPrevious Section
AbsorptionNext Section
Popular Courses
Find My Course
0:00 / 0:00

Accessory organs of the GI Tract

3 main glands
  1. Pancreas
  2. Liver
  3. Gal bladder
https://pixabay.com/vectors/digestive-system-human-digestion-41529/
PAGE BREAK

Pancreas

  • long shaped gland that feeds hormones into the duodenum of the small intestine
  • has a common duct with the gal bladder (bile duct)
  • Exocrine secretions of the pancreas include
  • Amylase
  • Lipase
  • Trypsinogen --> trypsin (activated by enteropeptidase from the brush border)
  • chymotrypsinogen --> chymotrypsin
  • procarboxypeptidase --> carboxypeptidase
  • phospholipase
  • colipase
  • The endocrine hormones insulin and glucagon are secreted from the islets of Langerhans and are spread throughout the body.
https://commons.wikimedia.org/wiki/File:Blausen_0699_PancreasAnatomy2.png
PAGE BREAK

Liver

  • made of liver cells called hepatocytes
  • highly vascularized, sending and receiving many substances in the body.
  • It receives a normal blood supply to keep it healthy (artery and vein for O2 and CO2 exchange
  • it also has an other vein attached which comes from other parts of the body and stops by on its way to the heart. It can deliver things to liver from the body. This special vein is called the heptic portal vein.
  • jack of all trades... has over 500 functions in the body
  • for this class, we just need to know that it:
  • secretes bile which is then stored in the gallbladder.
  • excretes bilirubin (pigment) into the blood as waste
  • stores and produces nutrients
  • processes drugs and hormones
  • gluconeogenesis (production of glucose from smaller molecules)
commons.wikimedia.org
PAGE BREAK

Gallbladder

  • Stores bile
  • bile is made of...
  • bile salts
  • cholesterol
  • bilirubin
  • water and ions
commons.wikimedia.org
0:00 / 0:00
List the main function of each digestive accessory structure in regards to the digestive tract

Liver: Bile production
Gallblader: Bile storage
Pancreas: produce the majority of enzymes needed to breath down chyme in the small intestine including....
  • Amylase
  • Lipase
  • Trypsinogen --> trypsin (activated by enteropeptidase from the brush border)
  • chymotrypsinogen --> chymotrypsin
  • procarboxypeptidase --> carboxypeptidase
  • phospholipase
  • colipase

0:00 / 0:00

Regulation of Digestion

Three main phases
  1. Cephalic Phase
  2. Gastric Phase
  3. Intestinal Phase

Cephalic Phase

  • gastric secretions begin
  • starts before food even enters the body. It is triggered by visual, auditory and olfactory sensations
  • these sensory signals are integrated in the amygdala and hypothalamus. They then send signals to the intestinal tract to prepare for a meal.
commons.wikimedia.org
PAGE BREAK

Gastric Phase

  • ingested food begins to activate gastric secretions
  • lack of food (when we are not eating) leads to inhibition of sensory activity
commons.wikimedia.org
PAGE BREAK

Intestinal Phase

  • occurs in duodenum as chyme arrives
  • stimulates hormonal responses (gallbadder and pancreas secretions begin)
  • Stimulates neural pathways (vagus nerve stimulation)

0:00 / 0:00
Which phase is responsible for both activation of stomach enzymes and inhibition of stomach enzymes? Explain how.

The intestinal phase is able to regulate the stomachs production of chyme. It does this by regulating its ability to creating chyme, i.e enzymatic breakdown. When the duodenum stretches, stomach enzymes are inhibited from being released. If there is not enough chyme, the small intestine can activate enzyme release through neural communication.