GASTROINTESTINAL AGENTS

• Main body of stomach

  Fundus
• Constricted area leading to intestine

  Pylorus
• Empty; covering with a layer of mucus which is alkali or neutral in reaction

  Stomach lining
• Saliva enzymes

  Amylase
• Esophagus uses peristalsis to push food
• Four gastric secretions

  Mucous cells

  Parietal cells

  Chief cells

  Enteroendocrine cells
• Secretes alkaline mucus

  Mucous cells
• Secretes HCl and intrinsic factors 

  Parietal cells
• Functions of HCl

  Denatures protein

  Kills bacteria

  Breaks up food

  Converts pepsinogen to pepsin
• Vitamin B12 absorption

  Intrinsic factors
• Inactive form of pepsin

  Pepsinogen
• Secrete and produce pepsinogen

  Chief cells
• Produces about 20 hormones

  Enteroendocrine cells
• G cells in pylorus

  Gastrin
• D cells in pylorus

  Somatostatin
• ECL-like cells in the fundus

  Histamine
• Inhibits release of gastrin

  Somatostatin
• Increases gastric secretions

  Gastrin
• Increases gastric production by parietal cells

  Histamine
• Three Gastric Activity Regulation

  Cephalic/Brain

  Gastric/ Stomach

  Intestinal
• Triggered by thought, smell, sight and smell

  Cephalic
• Triggered when food arrived at the stomach

  Gastric
• Triggered during the arrival of food at the duodenum

  Intestinal
• Normal ph level of the stomach

  1.6-1.8
• Absence of HCl in gastric secretions due to lack of pepsin activity

  Achlorhydria
• Gastric acidifiers:

  Dilute HCl

  Glutamic acid (Acidulin)
• Symptom of esophageal ulcer

  Heartburn
• More common type of ulcer and occurs less in patient with curvature stomach

  Gastric ulcer
• Causes of gastric ulcers

  Decrease pepsin activity

  Emotions

  Not always hyperacidity
• Alkaline bases that inactivates pepsin


  Antacids
• Ideal Antacids

  Not absorbable

  No systemic alkalosis

  Not a laxative

  Rapid effect but longer duration of effect

  Ph buffer

  Palatable

  Inexpensive
• Saline in taste and should not be given with tetracycline

  Sodium bicarbonate
• These antacids are not absorbed rather acts through physical adsorbtion

  Amphogel/ Al(OH)3

  Phosphogel/ AlPO4
• Neutralizes acids thru effervescence and can be used as dentrifice

  Calcium carbonate
• Side effect of CaCO3

  Constipation due to CaCl2
• Nitrogen in the blood

  Acetemia
• Not readily absorbed; insoluble in H2O but soluble in acids

  Magnesium-containing antacids
• Magnesium-containing antacids

  MgO

  Mg(OH)2

  Mg Trisilicate (Mg2O8Si3)
• Al(OH)3 + Mg (OH)2

  ALUDROX

  WINGEL

  MAALOX
• Al(OH)3 + Mg Trisilicate

  Gelusil

  Tricreamalate

  Triosgel