RBC and cancer metabolism Flashcards Preview

Year 2 Hematology > RBC and cancer metabolism > Flashcards

Flashcards in RBC and cancer metabolism Deck (31)
1

what will be observed in the serum following intravascular hemolysis?

hemoglobinuria

2

what will be observed in the serum following extravascular hemolysis (spleen)?

bilirubin (jaundice) - Hb has already been dealt with by macrophages

3

what is accomplished by RBC metabolism?

1. keeping iron reduced (2+)
2. maintaining K/Ca gradients
3. keeping protein SH groups reduced
4. maintaining cell shape

4

what is the relationship between NADH and MetHb?

NADH transfers electrons to MetHb to replenish the 2+ state

5

what is the role of ATP in maintenance of K/Ca gradients?

maintenance of ions across membrane

6

how do RBCs keep protein thiol groups reduced?

transfer electrons from glutathione to thiol groups to keep them reduced

7

where does glutathione get the electrons for reduction of thiol groups?

NADPH

8

what is the result of RBC metabolism failure?

1. cells fill with Ca2+
2. cells release K+
3. lose biconcave shape

9

what is the substrate that RBCs use for the PPP?

glucose-6-P

10

the RBC energy clutch bypasses which step of RBC metabolism?

phosphglycerokinase step converting 1,3-BPG to 3-phosphoglycerate

11

what is the result / purpose of the RBC energy clutch?

1. no consumption of ADP
2. net gain of ATP is zero

(saves one ADP expenditure and one ATP production per cycle)

12

in what circumstances is the energy clutch useful for RBC metabolism?

if cell is full of ATP but there is no ADP and you still need to make NADH

13

what regulates the energy clutch?

pH - lower pH increases activity - more NADH production

14

what are the two enzymes that compete for 1,3-BPG?

1. phosphoglycerate kinase
2. diphosphoglyceromutase

15

what are the regulated steps of glycolysis in RBCs?

1. hexokinase (glucose to glucose-6-P)
2. PFK1 (fructose-6-P to fructose-1,6-BP)

16

how do acidic pH levels impact glycolysis?

inhibition (less lactic acid production)

17

how is 2,3-BPG affected by low pH?

decreased

18

how is oxygen affinity affected by low pH? by what mechanism?

increased due to less 2,3-BPG, which is inhibited by low pH

19

what is the regulated enzyme in the PPP?

glucose-6-P dehydrogenase

20

what is the function of the PPP?

provide reduction equivalents in the form of NADPH

21

which enzyme is upregulated in response to low intracellular NADPH?

G6PD

22

what is the role of glutathione hydrolase?

1. keeps sulfydryl groups reduced
2. provides electrons to convert H2O2 to H2O

23

what is the role of SOD?

converts superoxide radical to H2O2

24

what is the role of glutathione peroxidase?

1. converts H2O2 to water
2. oxidizes GSH to GSSG

25

what is the role of glutathione reductase?

1. GSSG to GSH
2. NADPH to NADH

26

ultimately, where do the electrons for oxidant defense come from?

1. glucose to NADPH via PPP and NADP
2. from NADPH to GSSG via glutathione reductase

27

what are the two causes of nonspherocytic anemia?

1. G6PD deficiency - lack of NADPH
2. pyruvate kinase deficiency - lack of NADH / ATP

28

bite cells are seen with what condition?

G6PD deficiency

29

what are the components of the RBC cytoskeleton?

1. spectrin fibers - underlie plasma membrane
2. transmembrane proteins - band 3, glycophorin

30

how do the RBC cytoskeletal defects present?

hereditary spherocytosis

31

what is the most common RBC cytoskeleton defect?

ankyrin