Lecture 1: RBCs

Question 1

Where does oxygen bind haemoglobin?

Answer 1

Binds the iron ions in the haem (4 in every Hb - 1 per subunit)

Question 2

How much more oxygen is carried on Hb compared to plasma?

Answer 2

70X

Question 3

What is the equation for oxidative respiration?

Answer 3

C6H12O6 + 6O2 –> 6CO2 + 6H2O + 36ATP

Question 4

What is the equations for anaerobic glycolysis?

Answer 4

C6H12O6 –> 2 lactate + 2ATP

Question 5

How big is the small haem group in Hb?

Answer 5

616Da

Question 6

How big is the large globin peptide in Hb?

Answer 6

17000Da

Question 7

Describe HbA

Answer 7

2 alpha + 2 beta subunits

Question 8

Describe HbF

Answer 8

2 alpha + 2 gamma subunits
Binds O2 more strongly than HbA
Adults have a small percentage of HbF

Question 9

What is the Bohr effect?

Answer 9

Increase blood CO2 –> decrease affinity of Hb for O2
Decrease blood pH –> decrease affinity of Hb for O2
Because..
Increase blood Co2 –> decreases blood pH

CO2 and H+ bind Hb but in different place to O2

Question 10

What are the percentages of CO2 transport in blood?

Answer 10

Dissolved - 10%
Carbamino - 22%
HCO3- - 68%

Question 11

Describe the chloride shift for RBCs

Answer 11

CO2 + H2O –> H2CO3 + H+
The H+ goes on to bind Hb- to make HHb
The HCO3- leaves the RBC via an exchanger that brings Cl- into the RBC

More Cl- inside the RBCs in venous blood than arterial blood

Question 12

Describe O2 binding curves of Hb and myoglobin

Answer 12

Myoglobin - hyperbolic

Hb - sigmoidal

Question 13

What things cause rightward shift?

Answer 13

Rightward shift –> decreases affinity for O2

CO2, H+, Cl-, 2,3-DPG

Question 14

What is 2,3-DPG?

Answer 14

Binds to Hb, lowers the affinity of Hb for O2, found in erythrocytes at 5mM
Foetal HbF has higher affinity for O2 than HbA

Question 15

What happens in active muscles?

Answer 15

• O2 leaves the Hb (cooperativity)
• CO2 and H+ bind to Hb – shifts Hb saturation to right
• HCO3- leaves RBC  plasma
• Cl- leaves plasma  enters RBC (Cl- shift)

Question 16

What is the main driver to increase respiratory rate?

Answer 16

H+ in CSF

Question 17

How big are erythrocytes?

Answer 17

7uM by 2uM

Question 18

What cells are in 1ul of blood?

Answer 18

RBCs - 5million
Leukocytes - 9000
Platelets - 300,000

Question 19

Reference range of packed cell volume

Answer 19

M- 40-52%

F- 36-48%

Question 20

Reference range of Hb

Answer 20

M- 13-17g/dL

F- 12-16g/dL

Question 21

Reference range for Mean Cell Haemoglobin (MCH)

Answer 21

27-34pg

Question 22

Reference range for Mean Corpuscular Volumes (MCV)

Answer 22

80-100fL

Question 23

Erythropoiesis process

Answer 23

Haematopoetic stem cell –> BFU-E –> CFU-E –> erythroblasts (all these stages are erythropoietin dependent)

Erythroblasts –> reticulocytes (iron dependent)

Reticulocytes –> erythrocytes

Question 24

What is methaemoglobinaemia?

Answer 24

Fe in Hb is Fe3+ (oxidised) instead of the usual ferrous Fe2+

Question 25

How much stronger is COs affinity Hb compared to O2?

Answer 25

250%

Question 26

What is the treatment for CO poisoning?

Answer 26

95% O2 / 5% CO2 (CO2 drives the CO out of the binding pocket so O2 can bind)

Question 27

What are the types of polycythaemia?

Answer 27

Increased number of RBCs

Physiologic - due to living at high altitude

Polycythaemia vera - neoplasm, no cure, venesection