L9 Carbohydrate Metabolism II

• metabolic disorder occurs when abnormal chemical reactions in the body.
• Metabolism is carried out by chemical substances called enzymes, which are made by the body.
• The disorders usually result from an inability to break down some substance that should be broken down

  -allowing some intermediate substance that is often toxic to build up
• Type of disorder

  a)Acquired – Diabetic ketoacidosis, hyperosmolar coma, and hypoglycemia

  b) Inherited – G6PD deficiency, glycogen storage diseases, galactosemia, fructosuria & pyruvate kinase deficiency
• Cells of Islet of Langerhans monitor blood glucose levels.
• Regulated mainly by two pancreatic hormones

  ➢ Insulin : released by pancreatic β-cells when glucose high

  ➢ Glucagon : released by pancreatic α-cells when glucose low
• Increase blood glucose resulting the following signs & symptoms

  ➢ Hyperglycemia

  ➢ Glycosuria (glucose in urine)

  ➢ Polyuria (excess water excretion)

  ➢ Dehydration

  ➢ Polydipsia (increased thirst)

  ➢ Polyphagia (excessive hunger)
• Glucagon

  -inhibits – glycogen synthesis

  -Stimulates – gluconeogenesis, glycogenolysis & lipolysis
• Type I diabetes mellitus

  -No insulin is secreted by Islets of Langerhans

  -destruction of B cells

  -Must be treated by insulin injections
• Type II diabetes mellitus

  -Insulin normal or even elevated

  -associated with obesity

  -treated with insulin or drugs which increase tissue sensitivity to insulin
• G6PD deficiency

  -X-linked recessive inborn error of metabolism that predisposes to hemolysis

  -impaired NADPH production

  -can cause hemolytic anemia
• Role of NADPH in the RBC

  -prevents oxidative stress in cells

  -to reduce glutathione (reactions catalyzed by glutathione reductase).

  -Without NADPH, reactive oxygen species is converted to free radicals
• LIPID PEROXIDATION

  -oxidative degradation of lipids.

  -It is the process whereby free radicals"steal" electrons from the lipids in cell membranes

  -resulting in cell damage.
• Glycogen storage diseases

  -accumulation of glycogen

  -inherited as autosomal recessive traits

  -affect muscle characterized by weakness, cramping and muscle atrophy
• Von Gierke’s Disease

  -autosomal recessive disease.

  -Deficiency of glucose 6-phosphatase

  -Severe hypoglycemia
• Galactosemia

  -high blood level of galactose

  -Inherited autosomal recessive metabolic disorder

  -can damage the lens of eye, causing cataracts
• Defect in fructose metabolism

  -body has difficulty processing fructose

  -type of simple sugar found in fruits, some vegetables, and sweetened beverages
• There are two main types of fructose metabolism defects

  a)Hereditary fructose intolerance

  b)Essential fructosuria