27: Red Cell Metabolism - Schmidt Flashcards Preview

CS2 Exam II > 27: Red Cell Metabolism - Schmidt > Flashcards

Flashcards in 27: Red Cell Metabolism - Schmidt Deck (25):
1

erythrocytes lose nuclei __ entering circulation

before

mRNA disappears 1-2 d after release; no prtn synthesis, no replacement of damage, etc.

2

old, inelastic RBC are trapped in ___ and phagocytosed by _____

spleen; macrophages

extravascular hemolysis - no RBC lysis in vasculature

3

hereditary spherocytosis -->

spectrin mutation leads to rounded, short-lived cells

defects of cytoskeleton shorten RBC lifespan

4

neonatal jaundice, failed phototherapy, blood analysis shows hemolysis --> what might it be?

G6PD deficiency

infant has a problem producing NADPH leading to hemolysis

5

intravascular v. extravascular hemolysis

intravascular: mechanical disruption, relase of hemoglobin from RBC --> hemoglobinuria

extravascular: normal, removal of stiff RBC, relase of bilirubin from RBC, possible jaundice

6

4 purposes of RBC metabolism

- keeping iron reduced in Fe2+ form (NADH)
- maintaining K/Ca gradients (ATP)
- keeping prtn SH groups reduced (NADPH)
- maintaining cell shape (ATP)

7

If RBC metabolism fails (3 things) ...

- cells fill with Ca2+
- cells release K+
- lose biconcave shape

8

Red blood cell eats...

only glucose as an energy source

insulin has no effect on RBCs

9

look at slide 11

energy clutch and electron sources

10

what is the purpose of the energy clutch?

keep degrading 1.2bisphosphoglycerate even if no ADP available

11

2 regulated steps of glycolysis in RBC

- hexokinase
- phosphofructokinase I

acidic pH inhibit glycolysis - less lactate producton

12

acidic environment --> low 2,3 BP glycerate -->

increased binding affinity of oxygen to RBC

acidosis reduces 2,3BPG production

acidosis reduces 23BPG concentration and improves oxygen saturation

13

hemolytic crises triggered by:

infection, H2O2 producing drugs, Fava beans

14

see RBC with a bite taken out of them by a macrophage

G 6PD deficiency

also heinz body

15

blebbing of outer membrane of the RBC

pyruvate kinase deficiency

16

tumor cells get energy from..

glycolysis

produce large amounts of lactate

express hypoxia inducible factor 1a to support anaerobic metabolism

17

what is the cytoskeleton of RBCs like

mesh of spectrin under the PM with glycophorin and/or band/4.2/ankyrin anchoring to the membrane

18

most common cytoskeletal defect

hereditary spherocytosis

"rounding off of cells"

most commonly an ankyrin mutation but could be others

19

is glycolysis in RBC insulin dependent?

nope

20

provides reduction equivalents in the form of NADPH

PPP pentose phosphate pathway

21

low intraceullar NADPH -->

activates G6PD

pentose products are re-introduced into glycolysis

22

importance of glutathiione

GSH keeps sulfhydryl groups reduced

provides electrons to convert H2O2 to H20

23

what converts O2- to H2O2

superoxide dismutase

24

causes hemolytic anemia for lack of NADPH

G6PD deficiency

PPP defect

25

causes hemolytic anemia for lack of NADH/ATP

pyruvate kinase deficiency

glycolysis defect