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33 Cards in this Set
- Front
- Back
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Define a porphyrin
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organic compound, nitrogen, 4 pyrrolic rings
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In which cells are most heme synthesized
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erythroblasts in bone marrow
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what is the normal concentration of RBC
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4.5x10^6 microLiter
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describe hemoglobin
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large protein containing 4 subunits 2 alpha and 2 beta
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can heme external heme be used
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no, it must be synthesized de novo
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Portal simulation
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capillaries on two sides with a vein separating them. No artery in the middle
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What destroys old RBC's
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mainly splenic macrophages, however any macrophage can hence splenectomy is not a deadly procedure
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What are the functions of heme
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transport and storage of oxygen. Additionally, cytochromes work with heme in the ETC
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describe heme
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a tetrapyrrol molecule with an iron molecule in the middle
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how is heme produced
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Krebs plus glycine ----> ALA ---> PBG-----> heme
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What cells can make heme
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all of them due to the necessity of cytochrome production
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Porifria
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accumulation of porferin rings, absorbs light and is toxic, produce photosensitivity in the skin and colorful products in the urine.
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what problems can lead cause
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can decrease the heme pathway by acting on the first and last enzyme in the pathway. Also causes severe anemia
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where does heme catabolism mainly occur
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spleen
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what breaks apart heme
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splenic macrophages
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how do splenic macrophages break down heme
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they take the 4 pyrrol structure and break it into a linear structure called biliverdi which is converted to bilirubin
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how is bilirubin transported
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it is insoluble in water so it is attached to albumin
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what happens to the bilirubin that is not absorbed by the liver
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it causes the normal level of bilirubin in the body, not excreted in the urine
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what is the normal concentration of bilirubin in the body
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1 miligram per deciliter
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what does the liver conjugate bilirubin with
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glucoronic acid
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what does liver conjugation do to bilirubin
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it makes it soluble in water which is then put into the bile
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jaundice definition
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large amount of bilirubin in systemic circulation
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where in the cell does heme synthesis take place
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the first and last steps take place in the mitochondria and the middle steps occur in the cytoplasm
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biochemical steps to create heme
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succinyl CoA+glycine--->pyrrole---> tetra pyrrole---- porphyrin-----> ALA x2-----> porphobillnogen----> uroporphyrinogen III-----> protoporphyrin IX------> protoporphyrin IX plus ferrous iron equals heme
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what does globin do
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prevents oidation of heme
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heme + Fe 3+
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hemin
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what does free heme promote the translation of
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globin mRNA's
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what do hepatocytes do to bilirubin
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extract and conjugate it and then secrete it to the bile and feces
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what is used to change biliverdin to bilirubin
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NADPH +H+
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at what level is bilirubin toxic
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levels 20x above normal values
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what is jaundice
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a clinical sign, yellow discoloration of the skin, sclera and mucosae usually indicating bilirubin levels 3x above normal
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neonatal hyperbilirubinema can cause
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Kernicterus
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why do infants have issues with bilirubin
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the enzyme that conjugates bilirubin, UDPGT is low so bilirubin levels rise
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