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6 Cards in this Set
- Front
- Back
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Which cells/tissues have an absolute requirement for blood glucose?
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RBC, WBC, lens of the eyes and the kidney medulla
Note: The CNS "prefers" glucose but can use ketone bodies (acute hypoglycaemia leads to brain damage as no ketone bodies in blood unless chronic decline in glucose levels and stores) These tissues also have no reserves and solely rely on the blood |
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How is anaerobic glycolysis maintained? (What substance is produced and why? - lengthy answer!)
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Glycolysis reduces NAD+ to NADH, this noramlly gets oxidised by the mitochondria, but in a anaerobic state this cannot occur, as NAD+/NADH level are constant NAD+ will eventually run out ceasing glycolysis, so lactate dehydrogenase uses pyruvate to oxidise NADH back to NAD+
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What are the 3 main things the pentose phosphate pathway is important for?
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1. Cells without mitochondria (RBC) lack reductive power to stop protein conjugation (S-H -> S-S)
2. NAPDH improtant in fatty acid synthesis (Liver) 3. Ribose needed to produce DNA and RNA |
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What is the common feature of both types of galactosaemia and those of the more serious classical type?
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Common: galactosaemia -> galactitol = cataracts, Hypoglycaemia (babies) due to inability to convert galactose into glucose (milk high in galactose)
Classical: Retardation - Galactope-1-pi inhibits phosphoglucomutase (hypoglycaemia) and locks up Pi leading to damage in highly metabolically active tissues, jaundice as bilirubin cannot enter bile |
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Hexokinase commits glucose to glycolysis, what is the isoenzyme in the liver called and what is different about it?
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Glucokinase - Has a lower affinity (5mM) for glucose - This encourages liver to only use glucose when blood levels are higher and allows for glucose to be stored e.g. after a meal dampenning rise in blood sugar. Also stops use in glucogenolysis which is done primarily to maintain blood sugar no supply the liver.
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Glucose 6-phosphate dehydrogenase deficiency my be assymptomatic. What substances and what drugs can lead to the symptoms anaemia and jaundice?
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G6PDH is needed to creating reducing power in RBC, a deficiency leads to a reduced ability to cope with oxidative stressors. So oxidative agents and drugs (e.g. primiquine - antimalarial) can lead to anaemia as RBC lyse also increase heme breakdown (jaundice)
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