Final exam Flashcards
(132 cards)
GLUT 2 transporter
Facilitated diffusion from intestinal cell into blood for Glu, gal, Fru
Liver/pancreatic uptake - Low affinity, high capacity so only active in periods of high glucose
No hormonal control
GLUT 4 transporter
Muscle and adipose cell uptake
Regulated by insulin
Active only in high blood glucose (insulin active)
Decreased Insulin sensitivity and GLUT 4
Decreased sensitivity = decreased GLUT 4 = hyperglycemia
Regulation of hexokinase
Glucose –> G6P
Inhibited by G6P
PFK-1 Regulation
F6P –> F-1,6-BP
Activated by F2,6BP
Inhibited by citrate
FBPase-1 regulation
Gluconeogensis reaction
F1,6BP –> F6P
Activated by citrate
Inhibited by F2,6BP
Essential fructosuria
Defect in fructokinase –> elevated fructose in urine
Hereditary fructose intolerance
Aldolase B deficiency
F1P –> DHAP + Glyceraldehyde
Increase in F1P –> Phosphate trapping –> Inhibition of glycogenolysis and gluconeogenesis b/c no ATP available
Hereditary fructose intolerance symptoms
Hypoglycemia
Cirrhosis
Jaundice
Glycogen phosphorylase inhibited (Buildup in liver)
Galactokinase deficiency
Elevated blood galactose
Galacitol formation –> Cataracts
Classic galactosemia
Uridyl transferase deficiency
Elevated G1P:
Increased galacitol –> cataracts
Phosphate trapping –> fucked
Glucokinase
Liver glucose phosphorylater
Stimulated synthesis by insulin
Low affinity, high capacity
PFK2 Regulation
F6P –> F2,6BP
Stimulated by Ppase (via insulin)
Inhibited by PKA (via glucagon)
FBPase2 regulation
F2,6BP –> F6P
Stimulated by PKA (via glucagon)
Inhibited by PPase (via insulin)
Pyruvate kinase regulation
PEP –> Pyruvate
Activated by: F1,6BP, PEP, Ppase (via insulin)
Inhibited by: PKA (via glucagon), alanine
Pyruvate carboxylase regulation
Gluconeogensis rxn
Pyruvate –> OAA
Activated by Acetyl CoA
PEP carboxykinase regulation
OAA –> PEP
Inhibited by insulin
Activated by cortisol
Glycogen phosphorylation regulation
Glucagon/Epinephrine –> Gprotein and cAMP increase –> PKA activation
PKA –> Glycogen synthase inhibition
–> Phosphorylase kinase activation
PhosKinase –> glycogen phosphorylase activated
Glycogen phosphorylation and G6P
G6P inhibits phosphorylase kinase
Allosteric inhibition of Active GlycPhos
GSD Type 0: Enzyme defect, clinical features, biochem, workup/treatment
Defect: Glycogen Synthase
Clinical features: Fasting hypoglycemia, ketosis, hypoala, hypolactate
Post prandial hyperglycemia
Biochem: No glycogen, use alt resources in fasting
Workup: Fasting glu, ketones, ala, lactate
Treat: Avoid fasting
GSD Type 1a/1b: Enzyme defect, clinical features, biochem, workup/treatment
Defect: G6Pase and G6P transporter
Clinical Features: Hepatomegaly and liver dysfunction, kidney dysfunction, elevated TGs/cholesterol/VLDL, elevated lactate/ala, uricemia, platelet dysfunction and anemia, growth failure
Biochem: Glycogenolysis and gluconeogenesis inhibited by elevated G6P
Workup: Check values of above things
Treat: NG tube, diet
GSD Type II: Enzyme defect, clinical features, biochem, workup/treatment
Defect: Lysosomal acid maltase
Clinical features: Muscle related deficits. Hypotonia, areflexia etc
Buildup of glycogen in lysosome, but cytoplasmic glycogen is handled
GSD Type III: Enzyme defect, clinical features, biochem, workup/treatment
Defect: Debranching enzyme
Clinical features: Hepatomegaly and liver dysfunction, hypoglycemia, muscle wasting
Biochem: Short branches interfere with glycogen phosphorylase –> decreased breakdown so buildup in liver
Workup/treatment: Check fibroblast enzyme activity, liver function, glucose. Avoid hypoglycemia, increase protein
GSD Type IV: Enzyme defect, clinical features, biochem, workup/treatment
Defect: Branching enzyme
Clinical features: Severe and quick onset liver dysfunction and progression to cirrhosis
Biochem: Non branched glycogen hydrated and excess water stored in liver cells –> not good
Not many treatment options