GI and digestion terms to memorize


Cephalic phase

The first phase of digestion, when the sight and smell of food causes your brain to turn on the parasympathetic system and start your salivary glands and stomach working.


A starch-digesting enzyme produced in the saliva (salivary amylase) and the pancreas (pancreatic amylase)


Hydrocholoric acid, secreted by the stomach


The inactive form of pepsin, a protein-digesting enzyme produced by the stomach. It is activated by interaction with the HCl in the stomach


A protein-digesting enzyme produced by the stomach

Intrinsic factor

A compound produced in the stomach which allows you to absorb Vitamin B12


Produced to coat the stomach lining and protect it

Gastric phase of digestion

The second phase, beginning when you eat and food reaches the stomach. The stomach secretes GASTRIN. This phase lasts until the stomach contents enter the duodenum.


A hormone that makes the stomach get more excited and secrete more digestive enzymes and HCl. This is an example of positive feedback.


This is the stomach contents. It’s a mix of ground-up and partly digested food, HCl, and pepsin.

Intestinal Phase of digestion

This begins when the duodenum receives chyme from the stomach. The duodenal cells detect HCl, fats, and amino acids and begin to secrete SECRETIN and CHOLECYSTOKININ. They also secrete GASTRIC INHIBITORY PEPTIDE which turns off the stomach.


A hormone secreted by the duodenum. It goes into the blood and is carried to the pancreas, where it causes the pancreas to release bicarbonate (HCO3-) ions. These ions go to the duodenum and neutralize the HCl that just entered it from the stomach.

Cholecystokinin (CCK)

Means ‘gall bladder activator’. Causes the pancreas to secrete digestive enzymes and makes the gall bladder contract and shoot bile into the duodenum.


A compound made out of cholesterol and bilirubin. It emulsifies fats so you can digest them.


A strong protein-digesting enzyme produced by the pancreas


Fat-digesting enzyme produced by the pancreas

Brush border enzymes

Enzymes attached to the surface of small intestine epithelial cells, where they can break food molecules apart


Mixing fats and water together so the fats stay suspended in the water, instead of coming together into big lumps.

Exocrine pancreas

The part of the pancreas that produces digestive enzymes and bicarbonate and sends them out to the duodenum through the pancreatic duct

Endocrine pancreas

The part of the pancreas that produces insulin and glucagon and releases them into the blood

Islets of Langerhans or pancreatic islets

The clusters of cells that make up the endocrine pancreas

Pancreatic Alpha cells or A cells

The cells that make glucagon

Pancreatic Beta cells or B cells

The cells that make insulin. Always say PANCREATIC B cells, because there’s a whole different set of B cells in the immune system!

Hepatic portal vein

Takes the blood from your GI tract to the liver to be filtered before it is sent to the rest of your body

Hepatic sinusoids

The capillaries that take the blood through your liver. These get blocked in liver cirrhosis.


The liver cells that live along the sinusoids, filtering toxins and excess food out of the blood.

Hepatopancreatic ampulla or ampulla of Vater

The little nozzle that lets bile and pancreatic secretions empty into your duodenum.

Sphincter of Oddi

The little sphincter that opens or closes the hepatopancreatic ampulla