Red cell metabolism

Question 1

In order to fulfil its function, the red cell needs:

Answer 1

A supply of energy

A source of reducing power

Question 2

Mature RBCs have no DNA, RNA or mitochondria

which means what type of glycolysis and what else

Answer 2

Anaerobic glycolysis

hexose monophosphate shunt and glutathione system

Question 3

There is a lack of what synthesis in Mature RBC

Answer 3

Lack of protein synthesis

Question 4

Mutations affecting RBC enzymes either effect what

Answer 4

catalytic activity or cause premature inactivation.

Question 5

Glycolytic pathway =

Answer 5

glucose converted to pyruvate;

Question 6

One mole glucose in the Glycolytic pathway =

Answer 6

two moles ATP;

Question 7

What maintains intracellular cation balance

Answer 7

Na+ pumped out of RBC
K+ pumped into RBC
Membrane bound ATPase required

Question 8

What maintains RBC cell shape

Answer 8

Failure of energy production = reduction of cell deformability and shape changes

Question 9

Failure of Phosphorylation of glucose and fructose-6-phosphate prevents what

Answer 9

ATP production later in the pathway

Question 10

Hexose Monophosphate Pathway also called

Answer 10

pentose phosphate pathway

Question 11

Hexose monophosphate pathway consumes how much glucose - 5 - phospate

Answer 11

5-10%

Question 12

Amount of Hexose monophosphate pathway consumed depends on

Answer 12

Amount depends on NAD+ and ATP availability

Question 13

Glutathione cycle generates what

Answer 13

reducing power of the RBC via NADPH

Question 14

Generates reducing power of the RBC via NADPH - (glutathione cycle) for:

Answer 14

Oxidation/peroxidation of membrane lipids increases rigidity Reduction of methaemoglobin

Question 15

Generates reducing power of the RBC via NADPH - (glutathione cycle) for:

Reduction of methaemoglobin, how of occurs how often and reduces what

Answer 15

Occurs on a daily basis, reduces ferric to ferrous iron.

Question 16

Generates reducing power of the RBC via NADPH - (glutathione cycle) for:

Detoxification of oxidants occurs during

Answer 16

During methaemoglobin formation, reactive oxygen species are developed – superoxide and hydroxyl radicals

Question 17

2,3 DPG is formed from a

Answer 17

shunt involving 1,3 DPG, 3PG and DPG mutase

Question 18

The synthesis of one mole 2,3 DPG inhibits

Answer 18

the production of one mole ATP

Question 19

2,3 DPG inserts itself between

Answer 19

β-chains of deoxygenated Haemoglobin A

Question 20

Hereditary red cell enzymopathies are

Answer 20

genetic disorders

Question 21

enzymopathies cause hereditary

Answer 21

non-spherocytic haemolytic anaemias (HNSHA

Question 22

Enzymopathies are associated with what type of cell

Answer 22

with normocytic normochromic red cells

Question 23

Do enzymopathies have any

morphological characteristics

Answer 23

no

Question 24

Most common enzymopathies deficiencies include:

Answer 24

Glucose-6-phosphate dehydrogenase (G6PD)

Pyruvate Kinase

Question 25

The degree of haemolysis is enzymopathies is

Answer 25

variable.

Question 26

Factors to consider in enzymopathies is

Answer 26

Which pathway has been affected?
What is the role of the enzyme?
What functional abnormalities have been introduced?
How easy is it for the individual to compensate for the haemolysis

Question 27

Consequences of enzymopathies is

Answer 27

HNSHA
Splenomegaly
Jaundice
Iron overload
Non-haematological sequale

Question 28

PKLR encodes PK for

Answer 28

(R)ed cells and (L)iver:

Question 29

mutated PKLR / pyruvate kinase deficiency has the affect of

Answer 29

Reduced ATP production

Increased [2,3DPG]

Question 30

varying clinical features of PK deficiency

Answer 30

Jaundice
Blood transfusion requirements (dependency in some)
Pigment gallstones
Extravascular haemolysis

Question 31

Is there a link between residual PK activity and clinical severity.

Answer 31

NO

Question 32

Red cells deficient in G6PD develop a secondary deficiency in

Answer 32

Glutathione.

Question 33

X-linked condition

of G6DP linked too

Answer 33

Hemizygous in males

Variable presentation in females – Lyonisation

Question 34

Enzymopathy diagnosis includes

Answer 34

FBC: NCNC anaemia
Increased bilirubin
Increased LDH
Reduced haptoglobin
Raised reticulocytes
Exclude AIHA, membrane defects, haemoglobinopathies, enzyme investigations

Question 35

G6PD deficiency is associated with a

Answer 35

loss of red cell reducing power and haemolytic anaemia