Stomach secrete 2.5 L/day of acidic juice.

Active pepsin further activates pepsinogen by positive feedback mechanism

Chronic gastritis caused damage to the acid-producing cells of the stomach, so the patient develops achlorhydria and pernicious anemia because of the lack of the vitamen b12, because lack of the intrinsic factor

Insolube mucous forms a layer 1.5 mm in thickness.

Intrinsic factor & HCL are secreted from parietal cell (oxyntic cells)

pepsinogen is secreted from cheif (peptic) cells

soluble mucous is secreted from mucous neck cells

Insoluble mucous is secreted from Epithelium of the gastric body, esophageal &pyloric junctions, and the fundus.

1500 ml of pancreatic juice is secreted per day.

Pancreatic secretion is regulated by both nervous and hormonal mechanisms, but the hormonal regulation is the main mechanism.

In the nervous regulation of pancreatic secretion: the acetylcholine exerts its effects by activating phospholipase C. , the same as CCK hormone.

The effect of secretin on duct cells is due to increased intracellular c-AMP

The bile is secreted by the Liver cells

The maximum volume of the gallbladder is about 20-60ml, but I can store about 500ml (24 hours’ secretions)

During concentration of the bile: the concentration happens because of the active removal transport of Na, which passively draws Cl,HCO3, &H2O. The concentrations of bile salts, cholesterol, lecithin, and bilirubin are markedly increased.

Liver bile contains 28 mEq/L HCO3, while gallbladder bile contains 10 mEq/L.

The intestinal mucus secreted by the small intestine is in a form of mucins.

Intestinal mucus is secreted by:
A.surface epithelial cells though out the GIT
B.Goblet cells in the mucosa of the small intestine .
C.Brunner’s glands in the duodenum.

Brunner’s glands are inhibited by sympathetic stimulation , which causes peptic ulcers.

The intestinal alkaline fluid secretions are formed by the crypts of Lieberkühn