Gastrointestinal Disease Lecture Flashcards

Vocabulary flashcards covering gastrointestinal anatomy, cell types, acid secretion mechanisms, and common GI pathologies including PUD, GERD, and IBD.

Mucosa

The layer of the digestive tract that produces digestive enzymes and mucus for lubrication.

Submucosa

A layer of the digestive tract responsible for producing digestive enzymes, lubrication, and acid neutralization.

Muscularis externa

The digestive tract layer that facilitates the movement of contents along the gastrointestinal tract.

Serosa

The outermost layer of the digestive tract that produces serous fluid, forming a moist and slippery surface to reduce surface tension.

G cells

Gastric cells that secrete gastrin when stimulated by epinepherin, AA, $Ca^{2+}$ containing food, or alcohol.

Parietal Cells

Cells that secrete intrinsic factor and hydrochloric acid ($HCl$); they are stimulated by histamine ($H_2$) receptors, parasympathetic activity, and gastrin.

Chief Cells

Gastric cells that secrete pepsinogen and lipase.

ECL cells

Enterochromaffin-like cells that synthesize and secrete histamine when stimulated by gastrin and pitutary hormones.

Prostaglandin

Substances that inhibit proton secretion and stimulate mucus production in the stomach.

$H^+/K^+$ ATPase pump

Also known as the proton pump, this transporter on the luminal membrane is responsible for acid secretion.

Carbonic anhydrase

The enzyme that facilitates the reaction $CO_2 + H_2O \rightarrow H_2CO_3 \rightarrow H^+ + HCO_3^-$ during acid secretion.

Alkaline tide

The phenomenon caused by $HCO_3^-$ moving out to the blood from the basolateral membrane after a meal.

Dyspepsia

Common discomfort described as indigestion, gaseousness, fullness, or pain that is gnawing or burning, usually localized to the upper abdomen or chest.

Erosive gastritis

A type of stomach inflammation caused by a noxious irritant.

Acute gastritis

Transient mucosal inflammation usually caused by local irritants such as NSAIDS, alcohol, or bacterial toxins.

Chronic gastritis

Gastritis characterized by no visible changes and chronic inflammatory changes leading to atrophy of the glandular epithelium, most commonly caused by Helicobacter pylori.

Peptic Ulcer

A groups of ulcerative disorders in the upper GI tract characterized by a discrete mucosal defect in portions exposed to acid-pepsin secretion.

Hematemesis

The vomiting of blood, indicating a hemorrhage complication in peptic ulcer disease.

Melena

Black faeces resulting from gastrointestinal bleeding.

Perforation

A peptic ulcer complication where gastrointestinal content enters the peritoneum, causing peritonitis.

Penetration

A complication where a peptic ulcer erodes into adjacent organs such as the liver or pancreas.

Zollinger-Ellison syndrome

A gastrinoma or gastrin-secreting tumour that increases gastric acid secretion leading to ulceration.

GERD

GastroEsophageal Reflux Disease; the backward movement of gastric contents into the esophagus, often due to a weak lower esophageal sphincter.

Barrett esophagus

A complication of GERD where squamous mucosa is replaced with columnar epithelium, which is associated with increased risk of esophageal cancer.

Constipation

Condition defined as bowel frequency of less than 3 motions per week or needing to strain more than $25\%$ of the time.

Noroviruses

The most frequent pathogens associated with viral gastroenteritis leading to sudden onset of diarrhea and vomiting.

Irritable bowel syndrome (IBS)

A condition characterized by abdominal pain and altered bowel function for at least 12 weeks, with relief typically occurring after defecation.

Crohn's Disease

A form of IBD involving granulomatous lesions that can occur anywhere in the GI tract and affect all layers of the bowel wall.

Ulcerative Colitis

A form of IBD that commonly affects the rectum and colon, causing continuous inflammation primarily in the mucosal layer and stools containing blood and mucus.

Internal haemorrhoids

Haemorrhoids originating above the dentate line inside the rectum; they are generally not painful due to a lack of pain-sensing nerves unless they prolapse.

External haemorrhoids

Haemorrhoids that develop below the dentate line; they possess sensory fibres and are usually painful.

Thrombosis

The formation of blood clots within prolapsed external haemorrhoids, often turning them purple or blue.

Sitz Baths

A non-pharmacologic treatment for haemorrhoids where patients sit in warm water ($40-46\,^\circ\text{C}$) 2-3 times daily for 15 minutes.

Pathophysiology of GERD

Weakening of the lower esophageal sphincter (LES), impaired defensive factors (decreased salivation and salivary buffering capacity), impaired esophageal clearance (weak peristalsis delaying acid clearance), compromised mucosal defense (dilated intercellular spaces allowing acid to reach nerve endings), and delayed gastric emptying.