DIT review - GI 1 Flashcards by Giselle McIntyre

What are the neres that innervate each of the branchial arches

1st arch - CN V

2nd arch - CN VII

3rd arch - CN IX

4th-6th arches - CN X

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Describe the branchial origin, as well as nerves responsible for taste, sensation, and motor of anterior 2/3 of tongue

Anterior 2/3:
- Origin - 1^st and 2^nd branchial arch
- Taste - CN VII
- Sensation - CN V3
- Motor - CN XII

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Describe the branchial origin, as well as nerves responsible for taste, sensation, and motor of posterior 1/3 of tongue

Posterior 1/3:
- Origin - 3^rd and 4^th branchial arch
- Taste - CN IX, CN X (very posterior)
- Sensation - CN IX, CN X (very posterior)
- Motor - CN XII

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Most common location of salivary gland tumors

Parotid gland

Usually benign; if they are located in a smaller gland, more likely to be malignant

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Compare and contrast gastrischisis to omphalocele

Gastroschisis
- Defect in abd wall
- Extruding viscera not covered by sac
- Other anomalies less common
Omphalocele
- Defect in abd wall
- Extruding viscera covered by sac (composed of peritoneum and amnion)
- Liver often found protruding
- Other anomalies common

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Describe the defect and presentation of tracheoesophageal fistula

Most common type is esophageal atresia with distal tracheoesophageal fistula
- Aka blind upper esophagus with lower esophagus joined to trachea
Presentation:
- Polyhydramnios in utero
- Air in stomach (visible on X-ray) – due to fistula

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What are the components of CREST syndrome

Seen in limited type scleroderma

· Calcinosis / anti-centromere antibody

· Raynoud

· Esophageal dysmotility

· Sclerodactyly (tightening of skin with loss of wrinkles)

· Telangiectasias

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What is the metaplastic change associated with Barret esophagus

Nonkeratinized stratified squamous –> columnar

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What is Boerhaave syndrome

Transmural, usually distal esophageal rupture
Due to violent retching
Surgical emergency

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Causes of esophagitis

GERD
Candida (white pseudomembrane)
CMV (linear ulcers)
HSV (punched-out ulcers)

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Triad of Plummer-Vinson Syndrome

Dysphagia (due to Esophageal web)
Iron deficiency anemia
Glossitis

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What is the most common esophageal cancer in America and what are its associations?

Adenocarcinoma
- Occurs in distal 1/3 of esophagus
- Associated with chronic GERD, Barrett esophagus, obesity, achalasia
- More common in America

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What is the most common esophageal cancer worldwide and what are its associations?

Squamous cell carcinoma
- Occurs in the proximal 2/3 of esophagus
- Associated with alcohol, smoking, and hot liquids
- More common worldwide

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Describe the branches of the celiac trunk

Celiac trunk - Pharynx, esophagus, proximal duodenum, liver, gallbladder, pancreas, spleen
- Common hepatic artery
  - Gastroduodenal artery
    - R gastroepiploic - greater curvature of stomach (anastomoses with L gastroepiploic)
    - Anterior superior pancreaticoduodenal à head of pancreas, proximal duodenum
  - Right gastric artery - lesser curvature of stomach (anastomoses with L gastric a.)
  - Proper hepatic artery
- Splenic artery - spleen
  - Left gastroepiploic artery - greater curvature of stomach
- Left gastric artery - lesser curvature of stomach

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What is the purpose of gastrin, and how does it accomplish this?

G-cells
- Located in the antrum of the stomach (lower stomach)
- Produce gastrin in response to decreased HCl
  - Gastrin can directly stimulate parietal cells to make gastric acid, but . . .
  - Gastrin’s main mechanism of action is to increase acid secretion mostly via effect on ECL cells –> histamine release –> histamine activation of parietal cells
- Gastrin release stimulation by:
  - Phenylalanine
  - Tryptophan
  - Calcium

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What is Zollinger-Ellison syndrome

Gastrin-secreting tumor (gastrinoma) of pancreas or duodenum
- Too much gastrin à too much gastric acid à recurrent duodenal ulcers
Diagnosis:
- Positive secretin stimulation test
  - Gastrin levels remain elevated even after administration of secretin, which normally inhibits gastrin release

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Common causes of acute gastritis

NSAIDs - decreased PGE2 - decreased gastric mucosa protection
Burns (Curling ulcer) - hypovolemia - mucosal ischemia
Brain injury (Cushing ulcer) - increased vagal stimulation - increased ACh - increased H+ production

Causes of chronic gastritis

H. Pylori
Autoimmune – antibodies against parietal cells

Compare and contrast gastric vs. duodenal peptic ulcer disease (effect of eating, association with H. Pylori, other causes, risk for carcinoma)

Gastric ulcer:
- Pain worse with meals
- 70% due to H. Pylori
- Other causes include NSAIDs
- Increased risk of carcinoma
Duodenal ulcer:
- Pain decreases with meals
- 90% due to H. Pylori
- Other causes include Zollinger-Ellison syndrome
- Generally benign

What is triple therapy for H. Pylori

Triple therapy = PPI + clarithromycin (or metronidazole) + amoxicillin

What is menetrier disease?

Gastric hyperplasia of mucosa cells of the stomach
- Leads to hypertrophied rugae which look like brain gyri
Atrophy of parietal cells - decreased gastric acid production
Increased risk of gastric carcinoma

Presentation of gastric carcinoma

Weight loss, early satiety, acanthosis nigracans, Leser-Trelat sign

What is Sister Mary Joseph nodule

Gastric carcinoma metastasis to subcutaneour periumbilical

What is an acute gastric ulcer associated with elevated ICP or head trauma

Cushing ulcer

Brain injury (Cushing ulcer) - increased vagal stimulation -increased ACh - increased H+ production

What is acute gastric ulcer associated with severe burns

Curling ulcer

What is duodenal atresia and how does it present?

* Failure of the duodenum to recanalize, so it is basically a blind pouch * Presents as bilious vomiting and abdominal distension * X-ray will should “double bubble” * Buildup of air distal to the pyloric sphincter (within the blind pouch) * Buildup of air proximal to the pyloric sphincter within the stomach

Where is secretin produced and what is its function?

* Produced by S cells of the duodenum * Increase pancreatic HCO3- secretion in order to neutralize gastric acid * Decreases gastric acid secretion

Where is CCK produced and what is its function?

* Produced by I cells of the duodenum * Stimulated in response to fatty acids * Increases pancreatic secretions * Increased gallbladder contractility * Relaxes the Sphincter of Oddi * Decreases gastric emptying

Where is somatostatin produced and what is its function

* Produce by D cells of pancreas and GI mucosa * Shuts down everything: * Gastrin, CCK, Secretin, GIP, VIP, Insulin, Glucagon

Where is VIP produced and what is its function?

* Produced by smooth muscle cells in gut and parasympathetic ganglia * Relaxes smooth muscle and sphincters throughout the GI tract * Causes copious diarrhea

Symptoms of a VIPoma

* VIPoma - WDHA (watery diarrhea, hypokalemia, achlorhydria)

Name all of the retroperitoneal structures

SAD PUCKER: S - suprarenal (adrenal) glands A - Aorta and IVC D - 2-4th part of duodenum P - Pancreas (except tail) U - ureters C - Colone (ascending and descending) K - Kidneys E - thoracic esophagus R - rectum

Describe abetalipoproteinemia

* Autosomal recessive * Lack of apoprotein B * B48 needed for chylomicron secretion from the intestinal cells * Enterocytes fill with chylomicrons that cannot pass into circulation * Fat malabsorption, steatorrhea, failure to thrive * B100 needed for LDL reuptake in the liver

What is the characteristic histology of abetalipoproteinemia

Acanthocytes ("spur cells")

Pathogenesis and histology of celiac disease

* Autoimmune tolerance to gliadin (gluten protein found in wheat) * Wheat protein cross-reacts with small bowel tissue leading to: * Inflammation * Antibodies against gliadin and tissue transglutaminase * Histology: * Blunting of villi * Crypt hyperplasia * Intraepithelial lymphocytosis

Why can you get temporary lactose intolerance from enteritis?

* Lactase is located at tips of villi * Temporary lactase deficiency can occur with enteritis when there is injury to the tips of villi

Presentation of Tropical sprue

* Unknown cause – probably infectious * Looks like celiac but: * Affects the entire small bowel * Responds to antibiotics

What are the antibodies associated with celiac?

Anti-gliadin Anti-transglutaminase

What disease is associated with weight loss, diarrhea, arthritis, fever, adenopathy, and hyperpigmentation?

Whipple disease

Describe Whipple disease (cause, presentation, histology)

* Infection with Tropheryma whipplei * Symptoms: * Weight loss, lymphadenopathy, hyperpigmentation, cardiac symptoms, arthralgias, neurologic symptoms * Histology: * PAS (+) foamy macrophages in intestinal lamina propria

What is the characteristic histology of abetalipoproteinemia

* Will see abnormal star-shaped RBCs called acanthocytes (spur cells) - irregular spikes (vs. Echinocytes/burr cells) * Lack of apoprotein B * B48 needed for chylomicron secretion from the intestinal cells * Enterocytes fill with chylomicrons that cannot pass into circulation * Fat malabsorption, steatorrhea, failure to thrive * B100 needed for LDL reuptake in the liver