Digestive System Chp 4 (Exam 4)

Organs of the GI system

mouth and salivary gland, esophagus, stomach lining, small intestines, large intestines, anus, accessory organs (liver, gallbladder, pancreas)

GI mucosa

Lines the lumen of the alimentary canal (gastrointestinal tract). Its three major functions are:

(1) Secretion of mucus

(2) Absorption of the end products of digestion

(3) Protection against infectious disease

esophagus

Consists of the esophageal mucosa: nonkeratinized stratified squamous epithelium. Glands secret mucus as a bolus moves through the esophagus.

stomach

Consists of the epithelial lining, which is composed of goblet cells that produce a coat of alkaline mucus

mucous neck cells

secrete acid mucus

parietal cells

secrete HCl and intrinsic factor

chief cells

produce pepsinogen (inactive form of pepsin) and gastric lipase

enteroendocrine cells

secrete gastrin, histamine, serotonin, and somatostatin into the lamina propria

G cells

also secrete gastrin

acetylcholine (AcH), histamine, gastrin

HCl secretion is stimulated through second-messenger systems by:

only one ligand binds to parietal cells

if conc. of HCl is low

all three ligands bind to parietal cells

if conc. of hcl is high

GERD (Gastroesophageal Reflux Disease)

·        Commonly known as heartburn, it is when the stomach acid refluxes (flow back) into the esophagus.

·         It causes esophagitis with irritation, inflammation, and pain.

peptic ulcer disease

·         Caused by irritation of the mucous membranes lining the gastrointestinal track.

·         It can be located anywhere in the esophagus, stomach, or duodenum.

antacid drugs

Treats GERD.

This drug releases weak bases that neutralize HCl in the stomach. the higher pH (1) decreases the irritation of the gastric mucosa and (2) inhibits pepsin so that it does not break down the mucous membrane

H2 blocker drugs

Treats GERD and peptic ulcer disease.

This drug blocks the action of histamine by blocking its receptors. This stops the production of HCl.

Common suffix -tidine

proton pump inhibitor drugs

Treats esophagitis, GERD, heartburn, and peptic ulcer.

Decrease gastric acid by blocking the final step of acid production within the gastric parietal cell. Involves an enzyme system known as the proton pump.

Common suffix -prazole

Helicobacter pylori (H. pylori)

A spiral bacterium that has flagella. They live in the gastric or duodenal mucosa and are the cause of peptic ulcers that do not heal after standard treatment with the previously mentioned drugs.