CARDIO- Red Blood Cell Production and Survival

Question 1

what is the sequence of events forming a blood cell

Answer 1

hemocytoblast 
proerythroblast 
early erythroblast (ribosome synthesis)
late erythroblasts (Haemoglobin accumulation)
normoblast (ejection of nucleus)
reticulocyte
erythrocyte

Question 2

how is red cell production regulated

Answer 2

RBC number is inversely related to ambient O2 pressure

key regulator = erythropoietin

Question 3

how does erythropoietin regulate regulate RBC production

Answer 3

stimulus (hypoxia) - kidneys / liver release erythropoietin - erythropoietin stimulates the bone marrow - enhanced erythropoietin increased RBC count - increased O2 carrying ability of blood = homeostasis

Question 4

what does ferroportin do

Answer 4

helps absorption of iron from intestines into the blood

Question 5

what does erythroferrone do

Answer 5

inhibits hepcidin

Question 6

what sources is iron found in

Answer 6

meat, eggs, vegetables, dairy

Question 7

how is iron absorbed / regulated

Answer 7

gastric secretions and ascorbic acid help to absorb

DMT-1 and ferroportin regulate

Question 8

why is vitamin B12 / folic acid needed

Answer 8

essential for RBC maturation and DNA synthesis
needed for the formation of thymidine triphosphate
deficiency leads to failure of nuclear maturation

Question 9

what are the causes of iron deficiency

Answer 9

poor diet- inadequate intake / malabsorption
increased demand - pregnancy, growth
chronic blood loss
malabsorption

Question 10

what are the signs of iron deficiency

Answer 10

spoon nails

anaemia - microcytes, hypochromic (pale)

Question 11

what are the causes of B12 deficiency

Answer 11

inadequate intake
absorption defect
IF deficiency
drugs - anticonvulsants (inhibit absorption)

Question 12

what are the signs of B12/ folate deficiency

Answer 12

macrocytes - megaloblastic anaemia

hyper segmented neutrophils

Question 13

what are the treatments for deficiencies

Answer 13

Iron - iron infusion / tablets
B12- hydroxocobalamin
folate - give folic acid

Question 14

what are some other factors that affect nutrient levels

Answer 14

renal disease - ineffective erythropoiesis

reduced bone marrow erythroid cells

Question 15

what is ATP used for in RBC

Answer 15

maintaining shape and deformability, regulates intracellular cation concentration via Na/K pumps

Question 16

how does a G6PD deficiency affect red blood cell production and survival

Answer 16

G6PD deficiency = low NADPH and GSH

meaning there is acute haemolysis on exposure to oxidant stress; oxidative drugs or infections

Question 17

what is hereditary spherocytosis

Answer 17

loss of membrane integrity, RBC become spherical

deficiency in the protein with vertical interactions between the membrane skeleton and lipid bilayer

Question 18

what is hereditary elliptocytosis

Answer 18

mutations in the horizontal interactions (spectrin =, ankyrin, actin, protein 4.1 deficiency)

Question 19

what are haemoglobinopathies

Answer 19

mutations or deletions leading to the abnormal synthesis of globin chain in sickle cell disease / reduce rate of synthesis in thalassaemia

Question 20

what happens in sickle cell disease

Answer 20

point mutation in beta globin gene makes insoluble Hb when deoxygenated leading to polymerisation = sickle shaped cells

Question 21

what happens in thalassaemia

Answer 21

beta - loss of beta-chain causes mild microcytic anaemia
loss of both causes thalassaemia major
excess alpha chain precipitates in erythroblasts causing haemolysis and ineffective erythropoiesis

alpha thalassaemia - can be loss of 1,2,3,4

Question 22

outline hereditary forms out haemolytic anaemia`

Answer 22

intrinsic
intravascular
red cell membrane disorders - hereditary spherocytosis, elliptocytosis
red cell metabolism - G6PD / PK deficiency
haemoglobinopathies - sickle cell. thalassaemia

Question 23

outline acquired forms out haemolytic anaemia

Answer 23

extrinsic
extravascular
immune - autoimmune (warm/ cold)
alloimmune - haemolytic transfusion reaction/ haemolytic disease of the new-born

non-immune - infection, red cell fragmentation, chemical agents, secondary (liver/kidneys), PNH