B2 - RBC: production and function

Question 1

large early cells of RBC lineage

Answer 1

erythroblast/ pro-normoblast

Question 2

in the bone marrow macrophages feed the RBCs with

Answer 2

iron

Question 3

stimulus of EPO production

Answer 3

○ Stimulus to EPO production is renal O2 tension (low oxygen tension)
§ Caused by anaemia, major bleed, giving blood, low atmospheric O2 (high altitudes), defective cardiac or pulmonary function

Question 4

RBC membrane

Answer 4

phospholipid bilayer membrane with proteins
○ Proteins are inside to give structural integrity
○ Proteins that come out through the membrane that provide blood groups (ABO, Rhesus)

Question 5

red cell cytoplasm

Answer 5

red cells contain haemoglobin
○ Transports O2 from lungs to tissues
○ Returns CO2 to lungs

Question 6

iron is absorbed in

Answer 6

upper small bowel (acidic environment)

○ Will increase in times of iron deficiency

Question 7

percentage of iron ingested that is absorbed

Answer 7

5-10%

Question 8

iron delivery to normoblast

Answer 8

• Transported to bone marrow - bound to transferrin transport molecule
  
  • Delivers to transferrin receptor on developing normoblast
  • Taken up by developing normoblast to make haem

Question 9

excess iron stored in

Answer 9

macrophages as ferritin - some in liver some in bone marrow

Question 10

iron daily requirement

Answer 10

1-2mg per day
○ up to 3mg during pregnancy
○ 2mg for menstruating females

Question 11

when red blood cells die

Answer 11

they go to the spleen and the components are broken down and the iron is released and recycled by going back into ferritin storage form
○ Recycled

Question 12

• Deficiency of folate or Vit B12

Answer 12

○ Inhibits purine and thymidylate synthesis
○ Impairs DNA synthesis
○ Bone marrow is the most actively replicating organ in the body, and is therefore the first to be compromised by a vit B12 or folate deficiency
○ Deficiency in either of these creates a problem in the manufacture of any cell that is actively being produced in the body - major site is the bone marrow
○ Cause erythroblast apoptosis - erythroid cells being made in the bone marrow are going to die in the bone marrow because the nucleus isn’t being made properly
○ Results in anaemia from ineffective erythropoiesis

Question 13

B12 body stores

Answer 13

years

Question 14

folate body stores

Answer 14

3 months

Question 15

B12 also called

Answer 15

cobalamin because of cobalt ion

Question 16

B12 absorbed in

Answer 16

terminal ileum

Question 17

folate absorbed in

Answer 17

upper small bowel

Question 18

B12 comes from

Answer 18

animal products in diet

Question 19

folate comes from

Answer 19

vegetables in diet

Question 20

B12 deficiency blood film

Answer 20

• Hypersegmented neutrophil - too many nucleus fractions (more than 3 or 4)
  
  • Large red blood cells (macrocytic)
  • Ovoid shaped macrocytes

Question 21

alpha global chains on chromosome

Answer 21

16

Question 22

beta chains on chromosome

Answer 22

11

Question 23

delta and gamma genes

Answer 23

○ B gene part of a complex containing delta and gamma genes
§ Adult haemoglobin is 2 alpha and 2 beta
§ At birth, some are made of 2 alpha and 2 gamma

Question 24

sickle cell disease

Answer 24

• Point mutation in the gene that encodes the B globin chain
  
  • Results in abnormal B chain which is sticky and tactile
  • Sickle shaped elongated red blood cells
  • Stick together and stick across the microvascular tube and block the blood supply
  • Child with sickle cell anaemia will have killed most of their spleen through obstruction of blood by age 3 - autosplenectomy - infarcted spleen
    ○ Through obstruction of blood vessels
  • Can cause strokes if they get stuck in the brain
  • Present with pain at the time when tissue in being infarcted
  • Shortened life expectancy

Question 25

autosplenectomy in sickle cell anaemia

Answer 25

infarcted spleen through obstruction of blood vessels

Question 26

hereditary spherocytosis

Answer 26

• effects proteins of RBC membrane
  
  • Proteins in the membrane make it too rigid
  • RBC cant get through the spleen because it is not deformable
  • Spleen will either remove red blood cells completely or remove some of it’s membrane
  • When some membrane is lot, the red blood cell has to become tighter around the haemoglobin - causing a rounder shape
  • Spherical shaped red blood cells
  • Rigid round balls with firm membranes, no biconcave shape
  • Causes perpetual anaemia in chronic/severe cases
  • Sometimes will only be symptomatic during an infection where preferential destruction of red blood cells occur
  • RBC are removed by spleen

Question 27

red blood cell metabolism occurs through

Answer 27

• Embden-Meyerhof pathway

Question 28

• Embden-Meyerhof pathway

Answer 28

○ Generates energy for red blood cells
○ One molecule of glucose yields 2 ATP
○ ATP maintains RBC shape and energy for deformity
○ 2 molecules of lactate produced
○ Lactate is transported to blood and in the liver is converted into glucose
○ Uses pyruvate kinase

Question 29

RBCs metabolise glucose by

Answer 29

anaerobic glycolysis (requires no mitochondria or O2)

Question 30

pyruvate kinase deficiency

Answer 30

• Prickle shaped RBC
  
  • Acanthocytes - points/prickles on red blood cells
  • Don’t have any energy - cant undergo metabolism
    Spleen must be removed - to prevent red cells from being removed

Question 31

pyruvate kinase deficiency red blood film

Answer 31

acanthocytes