Updated: 2/13/2018

Neuronal Support Cells

Topic
Review Topic
0
0
Questions
1
0
0
Videos
1
Snapshot
  • A 26-year-old male presents with bilateral gradual hearing loss mostly of his left ear. He reports having difficulty hearing conversations when the phone is on his left side. Family history is significant for neurological disease in his father, but he cannot recall the name. He does state that his father complains of headaches and has to be followed every 3-5 years with an MRI of his brain and spine. Weber and Rinne testing suggest a sensorineural hearing loss mostly affective the left ear. Skin examination is shown on the right.
Introduction
  • Glial cells play a supportive role for neurons
    • outnumber the amount of neurons in the central nervous system (CNS)
  • Glial cells can be divided into macroglia and microglia
    • macroglia
      • three main types: oligodendrocytes, astrocytes, Schwann cells
    • microglia
      • cells of the immune system for the CNS
Neuroglial cells
 
Glial Cell (and Its Origin)
Function
Clinical Correlate

Astrocytes 

(neuroectoderm)

  • GFAP (+)
  • Foot processes envelope neurons and capillaries
    • mantain blood-brain barrier
  • Involved in neurotransmitter metabolism (e.g., GABA, glutamate)
  • Uptake excess K+ in the extracellular space, acting as a K+ buffer
    • thus maintain neuronal signaling efficiency
  • Neuronal injury → reactive gliosis (glial scar)
  • Contain glycogen granules
    • can provide glucose to neurons
  • Glioblastoma multiforme (grade IV astrocytoma)
    • primary brain tumor that is highly malignant
    • ability to cross the corpus callosum "butterfly glioma"
    • pseudopalisades on histology
      • associated with necrosis
Oligodendrocytes (neuroectoderm)
  • Myelinates neurons in the CNS
    • ~ 30 CNS axons
    • ↑ speed of conduction
      • via saltatory conduction
  • Fried egg-appearance on histology
  • Oligodendroglioma
    • classic histology findings of "fried egg" appearance with "chicken wire loop" capillaries
  • Multiple sclerosis
    • loss of oligodendrocytes can be histologically seen in white matter plaques
  • Progressive Multifocal Leukoencephalopathy (PML)
    • secondary to reactivation of JC virus infection in the immunocompromised → lytic damage to oligodendrocytes
Microglia (mesoderm)
  • CNS scavenger cells
    • phagocytic cell that has the ability to present antigens to lymphocytes
    • tissue damage (e.g., stroke, neurodegeneration, infection) leads to its activation
  • Originate in the bone marrow
  • Microglia infected with HIV multinucleated giant cells in CNS 
Ependymal cells (neuroectoderm)
  • Cililated cells that line the central canal and ventricles of the CNS
    • aids in moving cerebrospinal fluid (CSF) throughout the ventricular system
  • At certain places in the CNS, the ependymal cells are continuous with the choroid plexus
    • leads to CSF production
  • Ependymoma
    • commonly found in 4th ventricle
      • risk of leading to hydrocephalus
    • perivascular rosettes on histology  
Schwann cells (neural crest)
  • Myelinates axons in the peripheral nervous system (PNS)
  • Each cell myelinates 1 PNS axon
    • ↑ speed of conduction
      • via saltatory conduction 
  • Involved in nerve regeneration
  • Can act as phagocytes to remove debri post neuronal damage
  • Guillain-Barré syndrome (GBS)
    • respiratory or gastrointestinal illness → acute inflammatory reaction to peripheral nerves (may affect Schwann cells)
      • e.g., Campylobacter jejuni (classic), Mycoplasma pneumoniae
    • acute inflammatory demyelinating polyradiculopathy (most common subtype of GBS)
  • Vestibular schwannoma (acoustic neuroma)
    • commonly affects vestibular portion of cranial nerve VIII
      • can expand to the cerebellopontine angle after it fills the internal auditory meatus 
      • bilateral acoustic neuroma is a characteristic feature of neurofibromatosis type 2 (NF2)
        • mutation in merlin protein on chromosome 22
 

 
 

Please rate topic.

Average 3.5 of 11 Ratings

Thank you for rating! Please vote below and help us build the most advanced adaptive learning platform in medicine

The complexity of this topic is appropriate for?
How important is this topic for board examinations?
How important is this topic for clinical practice?
Questions (1)
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
Calculator

Question locked
Sorry, this question is for
PEAK Premium Subscribers only
Upgrade to PEAK
VIDEOS (1)
Topic COMMENTS (12)
Private Note