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Secreted in response to the movement of gastric acid.
-stimulates the liver, pancreas, gastric and intestinal cells to secrete HCO3 and H2O
Breaks down plant starches and glycogen into Maltose, maltitriose, and alpha dextrins (limit-dextrins) in the mouth
Breaks down alpha dextrins, sucrose, maltotriose, and maltose into glucose and fructose
Breaks down sugar from mushrooms, algae, fungi, and insects into glucose
Sodium Dependent Transporters
-Membrane Protein transporter
-allows glucose and galactose and Na
-Found in Renal and Intestinal cells
Membrane Protein Transporter-absorbs Fructose only
(found in intestines, testes, brain, liver, kidneys)
Insulin Sensitive Membrane Protein Transporter
(found in adipose, skeletal muscle, heart, brain-neurons and astrocytes)
Membrane Protein Transporter for cell types with barrier functions. High Affinity Glucose
(most cells, human erythrocyte, BBB, BRB, BPB, BTB, Brain (astrocytes/glial))
Membrane Protein Transporter
-high capaciity, bidirectional . Transports Glucose, Galactose, and Fructose
(found in Liver, Kidneys, Pancreatic B-cell, Serosal Intestine mucosa cells)
Membrane Protein Transporter-newly discovered
(found in brain-neurons, testes, adipose, muscle)
Fructose will be linked to ___ in the fed state and __ in the fasting.
What pathway is used to convert Galactose into Glucose in the liver and intestinal cells?
What enzymes are used?
Where are the highest concentrations of galactose found in a lab test?
-10 x more
-what is not metabolized in liver or intestine
In Classical Galactosemia, ______enzyme is deficient leading up to build up of _____ and _____.
(common in infants)
This Galactose metabolism disorder affecting mostly RBCs and WBCs from a deficiency of _______ enzyme.
What are some test results that confirm the diagnosis of Classical Galactosemia?
-Impaired liver function
-Elevated blood galactose levels
-Hyperchloremic metabolic acidosis
-Hyperaminoaciduria (high AA)
-High galacticol excretion in urine
-Increased Galactose-1-Phosphate inside RBCs
A buildup of Galactose caused by Galactokinase Deficiency can cause _____.
-fail to develop social smile
-fail to visually track moving objects
-same labs as others (look for enzyme in blood level)
How and why does Galactose get converted to Galactitol in neural tissue and lens of the eye?
-too much galactose in circulation
-Aldose Reductase (w/NADPH) converts to Galacticol
-cannot complete Polylol Pathway
What lab tests should be done to confirm galactose disorders in newborns?
-Blood test-from heel
-Urine-check for 3 enzymes:
2. Galacto-1-phosphate unidyltransferase
How to treat galactose disorders
-Eliminate lactose from diet
-Use Soy based formula
-Surgical removal of cataracts(only persistent ones)
Why is fructose used in gatorade?
-immediate source of energy
-active in both fed and fasting states
When does hexokinase convert fructose into fructo-6-phosphate to join glycolysis?
When there is not enough Glucose
-has higher affinity for Glucose
What enzyme is deficient in Fructose Intolerance?
-inhibits connection of fructose-1-phosphate to glycolysis
(in fed state)
How does fructose intolerance affect the fasting state?
It causes an accumulation of:
What is affected if phosphates are trapped?
-ATP, GTP synthesis
-glyconeogenesis, glycolysis, glycogenolysis
-leads to cell death
How will blood tests confirm fructose intolerance
-Liver fxn panel fail
How do you treat fructose intolerance
-Elimination of Fructose and Sucrose from diet
-may not prevent progressive liver disease
What is a consequence of fructose malabsorption?
-promotes bio-film in gut
-decreased tryptophan, folic acid,and zinc in blood
-decreased absorption of some nutrients
What lab tests are run to diagnose fructose malabsorption?
Hydrogen breath test(adults)
Stool acidity test (infants)
How will urine tests confirm fructose intolerance?
-Positive for reducing sugars (high levels of sugars)
What is fructosuria?
Deficiency of hepatic fructokinase
-cannot convert fructose to fructose-1-phosphate
-excess fructose excreted in urine
What is the two unit subunit enzyme that initiates glycogen synthesis?
-free in fasting state-liver
What is the substrate for the active site of glycogenin?
-made from galactose
-converted from glucose
What enzyme transfers a glucose molecule from UDP-glucose to the terminal residue of a glycogen primer?
What enzyme breaks 5-8 glucose residues from the chain to make a branch?
(amylo (a-1-4, a1-6) transglycosylase
What is an advantage of the ring structure?
-exposed carbon makes easy degradation/synthesis
In the fed state, what does insulin do?
-glucose to glycogen
-glucose to TG
-enzymes for carb metabolism
-inhibits glycogenolysis enzymes
What is a type 0 glycogen disorder?
-failure to thrive
What is a type 4 glycogen disorder?
-altered glycogen structure
Why is sorbitol not converted to fructose to limit cell damage?
Sorbitol is produced faster than it can convert to fructose.
-cannot leave cell-toxic
-leads to cell lysis and loss of function
-peripheral tissue cells
-blood vessel cells
What tissue uses lactate for energy?
(provided from RBCs, seritoli cells, astrocytes,muscles)
What enzyme starts the breakdown of glycogen by breaking the a-1,4 bonds
-pyridoxal (b6) cofactor
What enzyme goes into effect during glycogenolysis when there are only four glucose molecules left on a branch?
(4:4 transferase), then
Where do the G-6-P molecules end up after glycogenolysis?
-Pentose Phosphate Pathway
What three hormones regulate glycogenolysis in the liver?
Glucagon, cortisol, and epinephrine
-released due to hypoglycemia
-fasting, low carb diet, sleep, exercise
-stress on the body
What hormone counters the effect of insulin and stimulates gluconeogenesis to increase blood sugar levels?
What is affected in Type 1 VonGlerke's glycogen disorder
-stops conversion to glucose
What is affected in Type III Cori's glycogen disorder?
-no free glucose
-altered glycogen structure
What is affected in Type V McArdle's glycogen disorder?
-no breaking of glycogen
What is affected in Type VI Hers' glycogen disorder?
-no glucose to brain
-breaks down AA/FA
What is lactogenesis and where does it occur?
production of Lactose
-mammary glands in females
-uses both glucose and galactose
What hormone stimulates lactogenesis?
-other hormones levels drop after childbirth leaving high levels of prolactin
-or suckling of infant
What enzymes are synthesized in response to prolactin and cortisol?
A-lactalbumin and galactosyltransferase
-increases production of lactose
What enzyme removes galactose from UDP galactose and bonds with glucose to create lactose?
-enhanced by A-lactalbumin
What is the first milk a breastfed baby receives?
What is special about it?
-high amounts of WBCs, and Antibodies
(more than mature milk)
What is in mature breast milk?
What glucose/galactose pathway creates no ATP, makes macromolecules for other functions in the body,and connects to the pentose phosphate pathway?
Uronic Acid Pathway
-AKA Glucuronic Acid Pathway
What is the clinical significance of glucuronides?
eliminates insoluble(non polar) substances from body
-out in urine and bile
-facilitates transport of insoluble drugs in body
What is the synthesis of glucuronides called and where does it take place?
-mainly in liver
-other-H,K,spleen, adrenal glands, thymus
Non polar substances that are transported by glucuronides
morphine, sleep drugs, cancer drugs
-Steroids,Thyroid hormones (T3 and T4)
-fatty acid derivatives
What compounds can help control the progression of cancer by increasing the rate of glucuronidation reactions?
- D-glucaric acid
-lung, skin, liver, breast, colon, bladder, and prostate cancer
How do the "anti-cancer" compounds work?
- inhibit the enzyme B-glucuronidase
- suppress cell proliferation and inflammation
How is Bilirubin transported in circulation?
-Bound to Albumin
-transported to liver
What happens to unconjugated Bilirubin in the liver?
-makes conjugated Bilirubin
What do intestinal bacteria do with conjugated bilirubin?
-90% converted to stercobilin/urobilin
-color of poo
What enzymes convert Heme to bilirubin?
Microsomal heme oxygenase
-biliverdin + Fe
-Fe stored as Ferritin
What is Jaundice or Icterus?
Excess unconjugated, conjugated, or urobilinogen in circulation or urine
What are the causes of Jaundice
-Too much unconjugated bilirubin-liver cannot conjugate all
-Hepatic disease-liver can't conjugate
-Liver disease-cannot reabsorb or re-excrete urobilinogen
-duct obstruction-backup of conjugated bilirubin
-over-abundance of u-b in blood
-increase urine urobilinogen
-increase fecal urobilinogen
-normal AST, ALT, ALP
-no urine bilirubin
-Increase AST and ALT
-Increase urine urobilirubin
-urine bilirubin present (dark)
-decrease fecal urobilirubin
Intrahepatic (Neonatal) <30 days old
Immature liver cells
-no Urine urobilinogen
-no fecal urobilinogen
Post Hepatic Jaundice (obstructive)
-urine bilirubin present (dark)
-no fecal urobilinogen (blocked)
-no urine urobilinogen
-normal AST, ALT
Causes and signs of liver disease
hepatitis exposure, transfusions, IV drug use, alcohol use, some meds, or family history
-blood test will specify
Tests to run to diagnose Jaundice
-plasma bilirubin-conjugated and total
-Liver Panel-AST, ALT, ALP, GGT
-measurement of coagulation time (PT)
What disease is marked by a unconjugated bilirubin level that rarely exceeds 50?
-enzyme for conjugation
Causes of Intra-hepatic Jaundice in Newborns
-Immature Liver Cells-can't conjugate or might leak into intestine
-unconjugation in intestine by B-glucuronidase -re-enters bloodstream
-RBC destruction - maternal IgG problems or conversion to adult Hb
What is the most severe form of Jaundice in newborns?
serum>300 of U-B
-no C-B in urine
-U-B and no uribilinogen in Meconium
What are some causes of post-hepatic obstructive jaundice?
-Cancer-mass closes lumen
-Gall Stones (>60yrs)
Possible treatments for neonatal jaundice
-takes care of skin color
IVIG-due to blood group incapatabilities
-exchange transfer of blood
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