GI and vitamins and minerals Flashcards
What does the stomach secrete?
1) Hydrochloric acid (HCI)
2) Bicarbonate
3) Pepsinogen
4) Intrinsic factor
5) Mucus
6) Prostaglandins
7) Glands of the stomach
8) Cells of the gastric gland
What are the cells of the gastric gland? What do they do?
1) Chief cells which secrete pepsinogen, a proenzyme that becomes pepsin when exposed to acid. Pepsin breaks down proteins (proteolytic)
2) Mucous cells (surface epithelial cells) provide a protective mucus coat that protects again self digestion by HCI and digestive enzymes
Whats the acidity of the stomach? Small Intestines? Lungs?
This is important for NG tube placement…
The stomach pH is 1-4 (prof said 4 in strip)
The small intestine is around 5
The lung is around 6-7
Know that theres many variables that can cause a shift in the pH of these areas but this is about the average.
What excretes HCI?
Parietal cells when stimulated by food.
What are some acid related diseases?
1) Peptic ulcer disease (PUD) Gastric or duodenal ulcers that involve the digestion of the GI mucosa by the enzyme pepsin.
2) Helicobacter pylori (H. pylori) Bacterium found in the GI tract in 90% of people with duodenal ulcers and 70% of those with gastric ulcers. First line therapy are 10-14 day course of PPIs and two antibiotics clarithromycin and amoxicillin.
3) Stress related mucosal damage are common in ICU patients and present as GI lesions. FActors include decreased blood flow, mucosal ischemia, hypoperfusion, and reperfusion injury, NG tubes.
What are antacids and what do they contain?
Antacids are basic compounds used to neutralize stomach acid. They are typically made aluminum, magnesium, calcium and/or sodium salts and some also contain simethicone (antigas).
What is the mechanism of action of antacids?
They do not prevent the overproduction of acid but instead help to neutralize acid secretions. It also helps promote gastric mucosal defense mechanisms (mucus, bicarb, prostaglandin secretion)
What are the drug effects of antacids?
Reduction of pain associated with acid-related disorders by reducing the acidity. It also works on reducing pain by increasing the resisitance of the stomach lining to irritation, inhibition of the protein digesting ability of pepsin, and increases the tone of the cardiac spincter.
Raising the gastric pH by 1 point neutralizes 90% of the gastric acid.
What are some H2 receptor antagonists and what do they do?
The most popular drugs for treatment of acid-related disorders are:
Cimetidine (tagamet)
Nizatidine (Axid)
Famotidine (Pepsid)
Rantidine (Zantac)
Over the counter version of the drugs are at lower doses
They reduce acid secretion.
What is the mechanism of action for H2 antagonists?
The competitively block the H2 receptor of acid-producing parietal cells reducing hydrogen ion secretion from the parietal cells, they do increase the pH of the stomach. They relieve many of the symptomes associated with hyperacidity-related disorders.
What is the mechanism of action of PPI’s?
They inhibit the release of hydrogen ions (protons) from the parietal cells into the stomach during HCI production. It IRREVERSIBLY binds to H+/K+ ATPase enzyme. This results in achlohydria where ALL gastric secretion is temporarily blocked, typically lasts 24 hours depending on the dose. This prevents ulcers.
What is the mechanism of action of sucralfate?
This is a cytoprotective drug, typically used in patients taking salicylic acid or aspirin. Its used for stressed ulcers, peptic ulcer disease.
Its attracted to an binds to the base of ulcers and erosions, forming a protective barrier over these areas. This protects it from pepsin.
What is the mechanism of action of Misoprostol?
Its a Prostaglandin E analog which have cytoprotective activity. It protects the gastric musosa from injury by enhancing local production of mucus or bicarbonate, promotes local cell regeneration, and helps to maintain mucosal blood flow.
This is used in the prevention of NSAID-induced gastric ulcers.
When treating duodenal ulcers often produces abdominal cramps and diarrhea.
