GI Flashcards
What is the function of the GI tract?
- Food digestion
- Absorption of nutrients and water
What are the primary GI disorders?
- ) Damage 2⁰ to gastric acid secretion
- drugs- manage acid production
- )Abnormal food movement through the GI tract (gastric motility!!)
- excessive motility (diarrhea)
- reduced motility (constipation)
- management of emesis (N and V)
The gastrointestinal system is divided into what 2 parts?
- The GI tract
- Accessory digestive organs
What are the three phases of digestion?
Cephalic phase:
- anticipation of food (sight, smell) initiates release of stomach acid
- parietal cells secrete acid (for pH between 1-4)
- mucoid cells secrete mucus for stomach lining protection
Gastric phase:
- gastrin released when antrum stretched
- triggers release of more gastric acid
Intestinal phase:
- chyme enters duodenum
- triggers negative feedback for reducing gastric acid/ proteolytic enzyme action in stomach
- release of bicarbonate solution and pancreatic enzymes to aid in digestion
Control of digestion is divided into ______ control and _______ control
neuronal and hormonal
Neuronal control consists of what mainly?
- Enteric nervous system: myenteric plexus and submucosal plexus
- parasympathetic
- Sympathetic system
- decreases motility
- controls mucus secretion
- increases sphincter control
Hormonal control consists of what?
- Gastrin- stimulate gastric acid secretion
- Pepsinogen- converts to pepsin, digests proteins
- Secretin- stimulates pancrease to secrete HCO3 sol
- Cholecystokinin- stimulates gallbladder release of HCO3
- Others
What is essential for activating digestive protease activity and controlling intestinal bacteria?
Gastric acids (HCl)
Gastric acids can also do what?
Can cause severe ulceration of stomach lining with accompanying hemorrhage if produced excessively or if stomach lining is damaged.
Acid reducing agents work by stopping this process, block proton pump
2 acid-related GI conditions
- Peptic Ulcer
- GERD
What are peptic ulcers?
Ulceration of the mucosal lining of the esophagus, stomach, and/or duodenum
What is GERD?
Gastroesophageal reflux disease
-stomach contents leak backwards from the stomach into the esophagus (AKA: heartburn or acid indigestion)
Acid-suppressive drugs: Antacids MOA?
AE?
-neutralize gastric acidity
- AE: effervescent types (ie Alka-seltzer) have high sodium contents
- magnesium products- diarrhea
- aluminum and calcium- constipation
- DD interactions
- alter absorption of electrolytes from GI tract = e- inbalance
- avoid taking within 2 hrs of other oral medication
What is the primary use of Antacids?
- treat acid reflux
- increase stomach pH from 1.3 to 3.5 which produces symptomatic relief and some ulcer healing
What are some examples of antacids?
- calcium carbonate (tums)
- magnesium hydroxide (milk of magnesia)
Acid-suppressive drugs: Proton Pump Inhibitors MOA?
AE?
-irreversibly inhibits H+/K+ ATPase pump on parietal cell membrane which blocks final step in acid secretion into lumen of stomach
- generally well tolerated
- long term use associated with gastric polyps, altered calcium metabolism, some CV abnormalities
What is the primary purpose of Proton Pump Inhibitors?
-treat acid reflux and heal ulcers
Which has been shown to be more effective in treating acid reflux and healing ulcers: PPI or H2 Antagonist?
PPI
What are three mucosal protectors?
- Bismuth chelate
- Sucralfate
- Misoprostol
What can H. pylori infections cause?
What is used to treat it?
-chronic gastritis, PUD, GERD, gastric cancer
-Combination therapy: acid-controlling drug + antibiotic
Ex:
-colloidal bismuth, tetracycline, and metronidazole
-PPI plus 2 antibiotics
Treatment can eliminate bacteria within _____
1 week