Updated: 12/22/2018

Gastrointestinal Tract Histology

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Overview of Gastrointestinal Tract Histology
GI Tract Anatomy
  • Radial organization of gastrointestinal tract
    • wall of tubular gastrointestinal tract consists of 4 concentric layers:
      • mucosa
        • epithelium
          • typically a simple cuboidal or a simple columnar epithelium
          • secretory function in stomach
          • secretory and absorptive functions in small intestine and large intestine
        • lamina propria
          • supports avascular mucosal epithelium
            • contains blood and lymphatic vessels
        • muscularis mucosae
          • typically a double layer of smooth muscle
            • inner layer of circularly oriented smooth muscle
            • outer layer of longitudinally oriented smooth muscle
          • contraction causes local movement in mucosa
      • submucosa 
        • a layer of connective tissue 
        • contains large blood vessels and large lymphatic vessels
        • contains submucosal (Meisnner's) nerve plexus
        • anchors the mucosa to the muscularis externa
      • muscularis externa
        • a double layer of smooth muscle
          • inner layer of circularly oriented smooth muscle
          • outer layer of longitudinally oriented smooth muscle
      • contains myenteric (Auerbach's) nerve plexus in between double layer of smooth muscle
      • contraction causes peristalsis
      • adventitia / serosa
        • a layer of connective tissue
Distinctive Features of Gastrointestinal Tract Histology
  • Esophagus
    • esophageal mucosa
      • non-keratinizing, stratified squamous epithelium
      • muscularis mucosae is a single layer of longitudinally oriented smooth muscle
    • esophageal muscularis externa
      • upper one third of esophagus
        • striated muscle
      • middle one third of esophagus
        • striated muscle and smooth muscle
      • lower one third of esophagus
        • smooth muscle
  • Stomach
    • gastric mucosa
      • gastric glands occupy gastric mucosa
        • simple, branched, tubular glands that extend from muscularis externa to bottom of gastric pits
        • consist of mucus neck cells, parietal cells, chief cells, and G cells
        • elaborate gastric secretions into lumen of stomach via gastric pits
  • Small Intestine
    • overview
      • small intestinal mucosa
        • exhibits numerous projections, or villi, that protrude from epithelial layer of mucosal surface
          • villi increase surface area over which digestion and absorption occurs
          • epithelial layer of small intestinal mucosa is heterogeneous, composed of:
            • mucus-secreting cells (goblet cells)
            • absorptive cells (enterocytes)
              • exhibit numerous projections, or microvilli, that protrude from apical border
                • microvilli increase surface area over which digestion and absorption occurs
                • microvilli are responsible for characteristic striated border, or brush border, of enterocytes
        • frequency of villi and of microvilli in small intestine
          • jejunum > duodenum and ileum
        • frequency of goblet cells in small intestine increases as you progress down the small intestine
          • duodenum < jejunum < ileum
    • duodenum
      • duodenal mucosa
        • crypts of Lieberkühn, or intestinal glands, occupy duodenal mucosa
          • simple tubular glands that extend from muscularis externa to base of villi
          • elaborate small intestinal secretions into lumen of duodenum
      • duodenal submucosa
        • Brunner's glands, or submucosal glands, occupy duodenal submucosa 
          • elaborate alkaline (basic pH) secretions
            • likely function to neutralize acidic chyme propelled from stomach to duodenum of small intestine
          • peptic ulcer disease presents with hypertrophy of Brunner's glands  
    • jejunum 
      • jejunal mucosa
        • crypts of Lieberkühn, or intestinal glands, occupy jejunal mucosa
      • jejunal submucosa
        • plicae circulares are circularly arranged transverse folds containing a core of submucosa that extend partially around jejunal lumen
    • ileum
      • ileal mucosa
        • Peyer's patches, or aggregations of nodules of unencapsulated lymphatic tissue, occupy ileal lamina propria (and ileal submucosa)
          • M cells, overlying Peyer's patches, function as antigen-transporting cells
            • take up microorganisms and macromolecules
            • deliver antigens to antigen-processing macrophages
              • macrophages present processed antigen to lymphocytes
                • triggers secretory immunity
                  • stimulates B cells in germinal centers of Peyer's patches to differentiate into IgA-secreting plasma cells that reside in ileal lamina propria
        • crypts of Lieberkühn, or intestinal glands, occupy ileal mucosa
      • ileal submucosa
        • plicae circulares are circularly arranged transverse folds containing a core of submucosa that extend partially around ileal lumen (proximal ileum)
          • increase surface area over which absorption occurs
  • Large intestine
    • colon
      • colonic mucosa
        • "smooth" surface devoid of villi
        • crypts of Lieberkühn, or intestinal glands, occupy colonic mucosa
      • colonic muscularis externa
        • outer layer of longitudinally oriented smooth muscle is organized into 3 bundles, or teniae coli
    • anal canal
      • anal canal mucosa
        • keratinizing, stratified squamous epithelium

 

 

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Questions (4)
Lab Values
Blood, Plasma, Serum Reference Range
ALT 8-20 U/L
Amylase, serum 25-125 U/L
AST 8-20 U/L
Bilirubin, serum (adult) Total // Direct 0.1-1.0 mg/dL // 0.0-0.3 mg/dL
Calcium, serum (Ca2+) 8.4-10.2 mg/dL
Cholesterol, serum Rec: < 200 mg/dL
Cortisol, serum 0800 h: 5-23 μg/dL //1600 h:
3-15 μg/dL
2000 h: ≤ 50% of 0800 h
Creatine kinase, serum Male: 25-90 U/L
Female: 10-70 U/L
Creatinine, serum 0.6-1.2 mg/dL
Electrolytes, serum  
Sodium (Na+) 136-145 mEq/L
Chloride (Cl-) 95-105 mEq/L
Potassium (K+) 3.5-5.0 mEq/L
Bicarbonate (HCO3-) 22-28 mEq/L
Magnesium (Mg2+) 1.5-2.0 mEq/L
Estriol, total, serum (in pregnancy)  
24-28 wks // 32-36 wks 30-170 ng/mL // 60-280 ng/mL
28-32 wk // 36-40 wks 40-220 ng/mL // 80-350 ng/mL
Ferritin, serum Male: 15-200 ng/mL
Female: 12-150 ng/mL
Follicle-stimulating hormone, serum/plasma Male: 4-25 mIU/mL
Female: premenopause: 4-30 mIU/mL
midcycle peak: 10-90 mIU/mL
postmenopause: 40-250
pH 7.35-7.45
PCO2 33-45 mmHg
PO2 75-105 mmHg
Glucose, serum Fasting: 70-110 mg/dL
2-h postprandial:<120 mg/dL
Growth hormone - arginine stimulation Fasting: <5 ng/mL
Provocative stimuli: > 7ng/mL
Immunoglobulins, serum  
IgA 76-390 mg/dL
IgE 0-380 IU/mL
IgG 650-1500 mg/dL
IgM 40-345 mg/dL
Iron 50-170 μg/dL
Lactate dehydrogenase, serum 45-90 U/L
Luteinizing hormone, serum/plasma Male: 6-23 mIU/mL
Female: follicular phase: 5-30 mIU/mL
midcycle: 75-150 mIU/mL
postmenopause 30-200 mIU/mL
Osmolality, serum 275-295 mOsmol/kd H2O
Parathyroid hormone, serume, N-terminal 230-630 pg/mL
Phosphatase (alkaline), serum (p-NPP at 30° C) 20-70 U/L
Phosphorus (inorganic), serum 3.0-4.5 mg/dL
Prolactin, serum (hPRL) < 20 ng/mL
Proteins, serum  
Total (recumbent) 6.0-7.8 g/dL
Albumin 3.5-5.5 g/dL
Globulin 2.3-3.5 g/dL
Thyroid-stimulating hormone, serum or plasma .5-5.0 μU/mL
Thyroidal iodine (123I) uptake 8%-30% of administered dose/24h
Thyroxine (T4), serum 5-12 μg/dL
Triglycerides, serum 35-160 mg/dL
Triiodothyronine (T3), serum (RIA) 115-190 ng/dL
Triiodothyronine (T3) resin uptake 25%-35%
Urea nitrogen, serum 7-18 mg/dL
Uric acid, serum 3.0-8.2 mg/dL
Hematologic Reference Range
Bleeding time 2-7 minutes
Erythrocyte count Male: 4.3-5.9 million/mm3
Female: 3.5-5.5 million mm3
Erythrocyte sedimentation rate (Westergren) Male: 0-15 mm/h
Female: 0-20 mm/h
Hematocrit Male: 41%-53%
Female: 36%-46%
Hemoglobin A1c ≤ 6 %
Hemoglobin, blood Male: 13.5-17.5 g/dL
Female: 12.0-16.0 g/dL
Hemoglobin, plasma 1-4 mg/dL
Leukocyte count and differential  
Leukocyte count 4,500-11,000/mm3
Segmented neutrophils 54%-62%
Bands 3%-5%
Eosinophils 1%-3%
Basophils 0%-0.75%
Lymphocytes 25%-33%
Monocytes 3%-7%
Mean corpuscular hemoglobin 25.4-34.6 pg/cell
Mean corpuscular hemoglobin concentration 31%-36% Hb/cell
Mean corpuscular volume 80-100 μm3
Partial thromboplastin time (activated) 25-40 seconds
Platelet count 150,000-400,000/mm3
Prothrombin time 11-15 seconds
Reticulocyte count 0.5%-1.5% of red cells
Thrombin time < 2 seconds deviation from control
Volume  
Plasma Male: 25-43 mL/kg
Female: 28-45 mL/kg
Red cell Male: 20-36 mL/kg
Female: 19-31 mL/kg
Cerebrospinal Fluid Reference Range
Cell count 0-5/mm3
Chloride 118-132 mEq/L
Gamma globulin 3%-12% total proteins
Glucose 40-70 mg/dL
Pressure 70-180 mm H2O
Proteins, total < 40 mg/dL
Sweat Reference Range
Chloride 0-35 mmol/L
Urine  
Calcium 100-300 mg/24 h
Chloride Varies with intake
Creatinine clearance Male: 97-137 mL/min
Female: 88-128 mL/min
Estriol, total (in pregnancy)  
30 wks 6-18 mg/24 h
35 wks 9-28 mg/24 h
40 wks 13-42 mg/24 h
17-Hydroxycorticosteroids Male: 3.0-10.0 mg/24 h
Female: 2.0-8.0 mg/24 h
17-Ketosteroids, total Male: 8-20 mg/24 h
Female: 6-15 mg/24 h
Osmolality 50-1400 mOsmol/kg H2O
Oxalate 8-40 μg/mL
Potassium Varies with diet
Proteins, total < 150 mg/24 h
Sodium Varies with diet
Uric acid Varies with diet
Body Mass Index (BMI) Adult: 19-25 kg/m2
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(M1.GI.70) A 56-year-old woman with a longstanding history of gastroesophageal reflux presents for follow-up evaluation of endoscopically confirmed gastric and duodenal ulcers. Her symptoms have been unresponsive to proton pump inhibitors and histamine receptor antagonists in the past. Results for H. pylori infection are still pending. Which of the following changes is expected in the patient's duodenum, given her peptic ulcer disease? Review Topic

QID: 106493
1

Increased secretions from crypts of Lieberkühn

7%

(1/14)

2

Increased glucose-dependent insulinotropic peptide (GIP) release from K cells

0%

(0/14)

3

Hyperplasia of submucosal bicarbonate-secreting glands

79%

(11/14)

4

Expansion of gastrointestinal lymphoid tissue

0%

(0/14)

5

Proliferation of secretin-releasing S cells

14%

(2/14)

M1

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