Normal Erythrocytes

Question 1

Life span of mature RBCs

Answer 1

~120 days

Question 2

Which organ removes fragile old RBCs from circulation

Answer 2

Spleen

Question 3

Globular haemoglobin is broken down to what?

Answer 3

Amino acids (these then enter bloodstream)

Question 4

The haem group is converted to what?

Answer 4

Haem group (minus iron) is converted to bilirubin

-bilirubin is transported to liver and secreted into bile

Question 5

What happens to the iron?

Answer 5

Binds to transferrin and is recycled

Question 6

What is a proerythroblast derived from?

Answer 6

Myeloid stem cell

Question 7

What is special about the shape of red blood cells?

Answer 7

• diffusion distance minimised
• surface to volume ration maximised
• flexible membrane allows cells to squeeze in single file through capillaries

Question 8

RBC ion balance and cell volume are actively regulated by which ENERGY-DEPENDENT PUMP?

Answer 8

Na+/K+ ATPase (the sodium pump)

Question 9

RBC’s have no mitochondria so how do they make ATP?

Answer 9

Anaerobic glycolysis

-glucose is key fuel

Question 10

_____ from glycolysis helps keep iron in Fe2+ state?

Answer 10

NADH from glycolysis helps keep iron in Fe2+ state (HbFe3+ cannot bind oxygen!!)

Question 11

What is required for maintaining adequate levels of reduced glutathione? and how is it produced?

Answer 11

NADPH

-some glucose is metabolised through the hexose monophosphate shunt and this produces NADPH

Question 12

What releases O2 from Hb?

Answer 12

2,3, BPG (2,3 bisphosphoglycerate)

Question 13

Describe the structure of glutathione

Answer 13

Tripeptide consisting of glutamate, cysteine and glycine

Question 14

What does reduced glutathione do?

Answer 14

Combats oxidative stress

-helps protect against he toxic effects of free radicals

Question 15

What are free radicals?

Answer 15

Highly reactive molecules with unpaired electrons

-can lead to damage of cellular structures and enzymes

Question 16

What is the primary intermediate in oxidative damage and what protects against its effects?

Answer 16

Primary intermediate is hydrogen peroxide (glutathione detoxifies it)

Question 17

What is needed from the pentose phosphate pathway to produce reduced glutathione?

Answer 17

NADPH

Question 18

How is carbon dioxide transported? and how is this facilitated?

Answer 18

• dissolved in solution (10%)
• bound to Hb: carbamino-haemoglobin (30%)
• as bicarbonate ion (60%)

Facilitated by CARBONIC ANHYDRASE

Question 19

When fully saturated, 1g Hb will bind how many mls of oxygen?

Answer 19

1.34mls

Question 20

Normal haemoglobin concentrations in adults?

Answer 20

Males: 130-180 g/l
Females: 115-165 g/l

Question 21

Structure of adult haemoglobin

Answer 21

• 4 globin sub-units, each containing a single haem

- each haem contains a single Fe2+ ion and can bind one O2 molecule

Question 22

What is co-operativity?

Answer 22

The influence that the binding of a ligand to one site on the molecule has on the binding of ligand to a different functional site

Question 23

What facilitates the transfer of O2 from the mother to foetus?

Answer 23

• Foetal Hb has a higher affinity for O2 than adult

- HbF has a lower affinity for 2,3 BPG than does HbA