Lecture 2: Clinical Relevance of Cell Membranes and Transport Flashcards

1
Q

What is Niemann-Pick Disease?

A
  • causes deficiency in Acid-Sphingomyelinase (A-SMase) which normally breaks down sphingomyelin
  • defective enzyme = SM accumulation in: liver, spleen, CNS, and bone marrow LYSOSOMES
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2
Q

What are the symptoms of Niemann-Pick Disease?

A
  • enlarged liver and spleen (hepatomegaly and splenomegaly)

- neurological damage, “cherry red spot” in the eye

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3
Q

How does A-SMase cute sphingomyelin?

A

cuts the phosphate-choline off from the sphingosine backbone

  • creates: ceramide and phosphoryl-choline
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4
Q

Why is phosphatidyl serine (PS) a marker for apoptosis?

A
  • normally found in INNER LEAFLET of bilayer

- apoptosis occurs when PS is found on OUTER LEAFLET (phagocytes recognize and remove)

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5
Q

What is the role of Annexin V and FITC in PS apoptosis?

A
  • Annexin V binds to PS on apoptotic cell (in OUTER leaflet)

- FITC acts as fluorescent marker of Annexin V

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6
Q

What blood types are distinguished as the Universal Donor and the Universal Acceptor, and why?

A

Universal Donor = TYPE O

  • RBC’s have NO blood group antigens
  • can only receive from Type O (A/B antibodies)

Universal Acceptor = Type AB
- plasma has NO A/B antibodies

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7
Q

What is the Rh incompatibility between newborns and their mothers? (Erythroblastosis fetalis)

A
  • refers to D antigen (Rh+) –> autosomal dominant

Erythroblastosis Fetalis - incompatibility between mother (Rh-) and fetus (Rh+) blood

  • mother produces antibodies that attack fetus by crossing placenta
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8
Q

What is the importance of cholesterol in membranes?

A
  1. INCREASES fluidity in RIGID membranes
    • prevents close packing of saturated fatty acids)
  2. DECREASES fluidity in FLUID membranes
    • fit in gap between kink of unsaturated fatty acid tails)
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9
Q

What is Spur Cell Anemia?

A
  • type of hemolytic anemia, elevated cholesterol levels bound to RBC membranes
  • excess cholesterol from impaired liver cholesterol metabolism (Chronic Liver Dysfunction)
  • spiky RBC’s called ACANTHOCYTES
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10
Q

What are the symptoms of Spur Cell Anemia?

A
  • impaired RBC deformability = lyse as they pass through capillaries of spleen
  • prognosis poor, median survival = months
  • Liver Transplant = only potential curative option
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11
Q

What is Cystinuria and what are the symptoms associated with it?

A
  • autosomal recessive disorder
  • cause: defect in transporter (uptake) of Cysteine (and other dibasic AA’s –> Arginine, Lysine, Ornithine)
  • results in: cystine crystals in kidney
  • patients present with Renal Cholic (kidney stone-linked waves of abdominal pain)
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12
Q

What is Hartnup Disease and what are the symptoms associated with it?

A
  • autosomal recessive disorder
  • cause: defect in non-polar/neutral AA transporter (alanine, valine, threonine, leucine, TRYPTOPHAN)
  • results in: intermittent cerbellar ataxia (no muscle coordination), nystagmus, photodermatitis, photosensitivity
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13
Q

What are Cardiotonic Drugs and what do they act on?

A
  • contraction-inducing drugs (ouabain and DIGOXIN) –> CARDIAC GLYCOSIDES
  • inhibit Na/K-ATPase pump (cardiac myocytes) = INC. intracellular Na
  • impairs Sodium Calcium Exchanger (NCX) –> 2nd transport coupled it Na/K-ATPase pump
  • NCX impairment = Ca INC in sarco-endoplasmic reticulum
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14
Q

What is the effect of cardiotonic drugs?

A
  • increased sarcoplasmic Ca = INC cardiac contractile force
  • used for: Congestive Heart Failure, atrial fibrillation, dysrhythmias
  • cardiac glycosides EXTREMELY POTENT (become toxic over long periods of use)
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15
Q

What is Digitoxigenin?

A
  • cardiotonic drug
  • slowly reduces neuron resting potential to 0
  • side effects: disturbed vision, confusion, delirium
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16
Q

What is the cause of Cystic Fibrosis?

A
  • autosomal recessive disorder
  • cause: mutation in Cystic Fibrosis Transmembrane Conductance Regulator (CFTR) gene
  • defective CFTR protein –> misfolded, does not leave ER after translation
17
Q

What is the CFTR and what happens when it is defective?

A

a chloride ion channel that mediates active transport of Chloride from inside cells to outside in airways/sweat ducts

  • defective CFTR = buildup of Cl- inside airway epithelial cells (compensated by Na INC = NaCl)
  • water flows into airway to compensate salinity, decreasing surface mucous layer water content

THICKER mucous, airway susceptible to BACTERIAL INF