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MCM II > Lec 11 heme synthesis > Flashcards

Lec 11 heme synthesis Flashcards

1
Q

structure of Hemeoglobin

A

Porphyrin ring with iron present at the center (ferrous)

4 5 membered rings (pyrrole)

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2
Q

Phase 1 of heme synthesis

A
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3
Q

Phase II of heme synthesis

A
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4
Q

Phase III of heme synthesis

A
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5
Q

Lead poisoning and heme production

A

Lead inactivates ALA dehydratase and ferrochelatase

ALA and protoporphyrin ix accumulate

ALA is neurotoxic

causes anemia

impact energy production no cytochromes synthesized

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6
Q

What is Porphyrias

A
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7
Q

example of porphyrias that affect the erythropoietic

A

Congenital erythropoietic porphyria

defect in uroporphyrinogen III synthase (erythrocytes)

Photo sensitivity red urine

Auto recessive

buld up uroporphyrinogen I oxidise to uroporphrin I

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8
Q

Porphyrias that affect hepatic

A

Acute intermittent porphyria

defect in PBG deaminase (in liver)

too much ALA and PBG

Auto dom

ab pain and neuro dysfunction

Variegate porphyria (famous people had it)

defect protoporphyrinogen ix oxidase

Auto dom

photosens.

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9
Q

porphyria that affect hepatoerythropoietic

A

Porphyria cutanea tarda (PCT)

most common in us

defect uroporphyrinogen decarboxylase

auto dom

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10
Q

Heme degradation is under what system?

A

Reticulo-endothelial system

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11
Q

Globin broken down into what?

what happens to heme?

A

Globin broken down into aa

heme removed for degradation

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12
Q

Difference between heme and bilirubin?

A
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13
Q

What does heme oxygenase require?

what does it release?

A

oxygen

releases Carbon monoxide

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14
Q

What happens to the Fe2+ in heme once broken open?

A

changes into ferric iron Fe3+

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15
Q

Pathway from heme into billirubin

A
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16
Q

What happens once we have bilirubin?

A
  • Released to bloodstream.
  • Free/unconjugated/indirect BR insoluble
  • so bound to albumin
  • BR/albumin transport to liver
17
Q

what assists uptake of BR in hepatic tissue?

A

protein carrier

18
Q

what happens to Bilirubin in the liver?

A

UDP- glucuronate and bilirubin ix go to

bilirubin-monoglucuronide (direct)

via UDP-glucuronyltransferase

another UDP-glucuronate is added to this with same enzyme making

bilirubin-diglucuronide (direct)

19
Q

are bilirubin mono and di- glucuonide indirect?

A

no they are direct or conjugated and are now soluble

(conjugated with glucuronic acid)

20
Q

UDP-glucuronate formation

A

UDP-glucose converted UDP-glucuronic acid

via UDP glucuse dehydrogensase

21
Q

Bilirubin-diglucuronide in liver then does what?

A

moves to the gallbladder (part of bile)

22
Q

From gallbladder what happens (Path 1)

A

bilirubin-diglucuronide goes to bilirubin

bilirubin goes to urobilinogen

via microbial reduction

Urobilinogen gets reabsorb to kidneys

goes to urobilin (yellow color of urine)

23
Q

From gallbladder what happens (path two)

A

bilirubin-diglucuronide goes to bilirubin

bilirubin goes to urobilinogen

via microbial reduction

urobilinogen goes under further microbial reduction to red-brown stercobilin (feces color)

24
Q

Jaundice

A

hyperbilirubinemia

elevated levels of BR in blood stream

unconjugated/indirect (.2-.9)

conjugated/direct (.1-.3)

imbalance between production and exrecretion

25
Q

types of jaundice

A

pre-hepatic

intra-hepatic

post-hepatic

26
Q

Pre-hepatic jaundice (causes)

A

increased production of unconjugated BR

  • excess hemolysis (hemolytic anemias)
  • internal hemorrhage
  • liver capacity (uptake, conjugate, excrete)
  • glucose 6 PO4 dehydrog defic
  • incompatibility of maternal-fetal blood groups
27
Q

pre-hepatic findings

A

elevated blood levels unconj or indirect BR

normal conjugated BR

normal alanine aminotransferase (ALT) and aspartate aminotransferase AST

urobilinogen in urine (conjugate not impaired)

direct BR absent in urine

28
Q

Intra-hepatic causes

A

impaired hepatic uptake, conjugation, or secreition of conjugated BR

  • Hepatic dysfunction
    • liver cirrhosis
    • viral hepatitis
    • criggler-najjar syndrome
    • Gilbert syndrome
29
Q

Intra-hepatic findings

A
  • variable increases in unconjugated and conjugated BR depending on the cause (pre post conjugation)
  • increse in ALT AST in serum (hepatic dysfun)
  • urobilinogen levels normal
  • conjugated BR detected in urine
30
Q

Post-hepatic causes

A

problems with BR excretion

AKA cholestatic jaundice (decrease bile flow)

obstruct liver of bile duct

gall stone

carcinoma

liver disease

lesions

drugs

31
Q

Post-hepatic findings

A

elevated blood levels of conjugated BR

small increase in unconjugated form

Normal AST ALT

elevated ALP

conjugated BR in urine (dark)

no urobilinogen in urine

no stercobilin in feces (pale stool)

32
Q

Neonatal jaundice

A
33
Q

Phototherapy and neonatal jaundice

A
34
Q

crigler-Najjar syndrome

A

(type 1) deficiency of UDP-GT

complete absence of gene

BR accumulate in brain of babies (serious)

  • blood transfustions
  • phototherapy
  • heme oxygenase inhibitors
  • calcuim phosphate and carbonate (complex in gut
  • liver transplant
35
Q

criggler-Najjar syndrome type II

A

benign form

mutation in UDP-GT gene

10% activity

(not as severe)

36
Q

Gilbert syndrome

A

relatively common

reduced activity UDP-GT (25%)

BR <6mg/dL may icrease with fasting, stress

or alcohol consumption

37
Q

Hepatitis

A

inflammation of liver (liver dysfunction)

viral infec, alcohol cirrhosis, liver cancer

  • increased levels of unconj and conj BR
  • BR accum in skin and sclera yellow discolor
  • tea colored urine
38
Q

Bruises and their colors

A

breakdown of hemoglobin diff colors

  • Hemoglobin
  • heme-red
  • biliverdin-green
  • bilirubin-orange
  • iron-reddish brown (hemosiderin)

MCM II (11 decks)

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