Red blood cells: production and survival Flashcards
What does haematinic refer to? [4 marks]
Iron, vitmin B12, folate in red blood cell.
What are the first recognisable erythrocyte precursors on the bone marrow? [1 mark]
Proerythroblasts
Why is the cytoplasm of an erythrocyte basophilic? [1 mark]
Polyribosome
Why can hypoxia be caused by? [3 marks]
- Low erythrocyte count
- Decreased levels of haemoglobin
- Decreased availability of oxygen
What does erythropoietin do? [1 mark]
Stimulates red bone marrow to increase erythropoiesis
Which foods are sources of iron? [4 marks]
- Meat
- Eggs
- Vegetables
- Dairy food
How is iron absorbed? [2 marks]
- 5-10% absorbed in the duodenum and jejeunum
- Divalent metal transporter 1 and ferroportin transport iron from the duodenum and jejunum
What causes iron deficiency? [3 marks]
- Decreased uptake
- Increased demand
- Increased loss
How disease can cause malabsorption of iron? [1 mark]
Celiac disease (villi of the small intestine is damaged)
What is mean cell volume and how is that calculated? [2 marks]
- The average volume of each red blood cell
- The ratio of haematocrit to the red blood cells count.
What does low mean cell volume mean? [1 mark]
Microcytic anaemia
What is vitamin B12 and folic acid needed for? [3 marks]
- RBC maturation
- DNA synthesis
- Formation of thymidine triphosphate
What is vitamin B12 a coenzyme for? [1 mark]
Methionine synthase
What is intrinsic factor and where is it produced? [2 marks]
- A glycoprotein produced in the stomach
- Binds to Vitamin B12 and takes it to the ileum
What is the cause if folate deficiency? [4 marks]
- Inadequate intake
- Absroption defect (i.e. coeliac, Crohn’s, Tropical sprue)
- Increased demands/losses
- Drugs
How do anticonvulsants cause folate deficiency? [1 mark]
They affect its absorption
What happens to erythrocytes in folate & B12 deficiency? [3 marks]
- Megaloblastic anaemia (large, nucleated immature progenitor)
- Macroovalocytes (large, oval RBC)
- Hypersegmented neutrophil
Which foods can you get vitamin B12 and folate? [4 marks]
VITAMIN B12: Animal produce
FOLATE: Liver, greens and yeast
What are the daily requirements and of vitamin B12 and folate? [2 marks]
VITAMIN B12: 1-2μg
FOLATE: 100-150μg
How much vitamin B12 and folate is stored in the body? [2 marks]
VITAMIN B12: 2-3μg
FOLATE: 100-150μg
Where is vitamin B12 and folate stored? [3 marks]
VITAMIN B12: Ileum
FOLATE: Duodenum & jejunum
How is vitamin B12 and folate transported in plasma? [2 marks]
VITAMIN B12: Bound to TCII and transported
FOLATE: It weakly binds to albumin
What else affects red blood cell production? [3 marks]
- Renal disease (affects erythropoiesis)
- Aplastic anaemia (failure of RBC production in bone marrow)
- Leukaemia
How is haemolytic anaemia classified? [3 marks]
- Hereditary/Congenital vs. Acquired
- Intrinsic vs. Extrinsic
- Intravascular vs. Extravascular
What causes hereditary spherocytosis? [1 mark]
Mutations in one of the peripheral proteins (Spectrin, ankyrin, protein 4.1, actin)
What causes hereditary elliptocytosis? [2 marks]
- A mutation in spectrin
- Causes defective spectrin-ankyrin association
What does glucose-6-phosphate dehydrogenase do? [2 marks]
- Catalyses production of NADPH, which reduces glutathione
- Important in the pentose phosphate pathway
What does pyruvate kinase do? [3 marks]
- Produces ATP and pyruvate
- ATP maintains shape, flexibility and cation pumps of RBCs
- Important in glycolytic pathway
How is glucose for RBCs produced? [2 marks]
- Glycolytic pathway: produces 90%
- Pentose phosphate pathway: produces 10%
What happens in G6PD deficiency? [2 marks]
- Oxidative damage to RBCs and haemolysis
- Heinz bodies (inclusions of denatured Hb)
What benefit can G6PD deficiency have? [1 mark]
Protection against malaria
What happens in PK deficiency? [4 marks]
- Cation pumps fail to function
- RBC lose a lot of potassium and water
- Causes chronic non-spherocytic haemolytic anaemia
- Excess haemolysis leads to jaundice
What is extravascular haemolysis? [2 marks]
- Haemolysis in macrophage
- Normal
What is intravascular haemolysis? [2 marks]
- Haemolysis in bloodstream
- Abnormal
