Bilirubin Metabolism Quiz

Bilirubin Levels

• Normal range for total serum bilirubin is approximately 0.1 to 1.2 mg/dL.
• Normal range for serum indirect (unconjugated) bilirubin is typically 0.2 to 0.8 mg/dL.
• Normal range for serum direct (conjugated) bilirubin is about 0.0 to 0.3 mg/dL.
• Conditions such as Gilbert syndrome are associated with biochemical disturbances in bilirubin metabolism.

Hyperbilirubinemia

• Hyperbilirubinemia is defined as elevated levels of bilirubin in the blood, commonly indicating liver dysfunction or hemolysis.

Gastrointestinal Smooth Muscle

• The normal resting membrane potential in smooth muscle fibers of the gastrointestinal tract is around -50 to -60 mV.
• Slow waves in gastrointestinal smooth muscle are characterized by rhythmic fluctuations in membrane potential that do not always lead to contraction.
• Frequency of slow waves varies:
  • Stomach: approximately 3 cycles per minute (cpm)
  • Duodenum: about 12 cpm
  • Ileum: around 8 to 9 cpm
• Average intensity of slow waves in smooth muscle is moderate, enough to trigger action potentials when reaching a threshold.
• The rhythm of contraction in the duodenum is based on the higher frequency of slow waves (approximately 12 cpm), facilitating more frequent contractions.