44. Blood (TT)

Question 1

What is bilirubin?

Answer 1

• Yellowish substance in your blood.
• It forms after red blood cells break down.

Question 2

What structure is this?

Answer 2

Bilirubin - It is like a haem group, but with an open ring.

Question 3

What is the purpose of metabolism of bilirubin in the liver?

Answer 3

It is conjugated so that it is more soluble in water and can be more easily excreted.

Question 4

What is bilirubin conjugated to in phase II metabolism in the liver?

Answer 4

Glucuronate

Question 5

Write the equation for the phase II metabolism of bilirubin in the liver. What enzyme catalyses this?

Answer 5

UDP-Glucuronate + Bilirubin -> Bilirubin glucuronide

Enzyme: UDP glucuronosyl transferase

Question 6

How is bilirubin relevant in clinical tests?

Answer 6

Levels of bilirubin can be used to estimate liver function.

Question 7

What are some conditions that may be caused by high levels of bilirubin? [IMPORTANT]

Answer 7

• Jaundice
• Kernicterus

Question 8

What is neonatal jaundice, what causes it and what are some of the symptoms?

Answer 8

• A condition resulting from build up of bilirubin in young children, giving them a yellowish colour
• This occurs because the levels of UDP-glucuronosyl transferase are too low in the liver for metabolism and excretion of bilirubin

Question 9

How and why are the symptoms of jaundice different in adults and children?

Answer 9

• In adults, the blood-brain barrier is well-developed with tight junctions, meaning that there is little risk of the bilirubin affecting the brain
• In children, the barrier is not as well developed, so the bilirubin can affect the brain and cause kernicterus

Question 10

What is kernicterus, what are the causes and symptoms, and who does it affect?

Answer 10

• A type of brain damage that can result from high levels of bilirubin in a baby’s blood, usually caused by jaundice
• It can cause athetoid cerebral palsy, hearing loss, problems with vision and teeth, and sometimes intellectual disabilities.
• It affects babies due to their poorly-developed blood-brain barrier.

Question 11

What can be used as therapy for neonatal jaundice and kernicterus? How does this work? [IMPORTANT]

Answer 11

• Phototherapy
• This involves shining a blue light on the baby that causes a double bond in bilirubin to pivot from cis to trans

Question 12

Add flashcard about: “Significance of conjugated and unconjugated bilirubin in liver function tests in investigation of causes of jaundice”.

Answer 12

Do it!