Lecture 1: Red Blood Cells Flashcards
how soluble is oxygen in plasma
poorly soluble
how many ATP molecules does a glucose molecule produce
36
what is haemoglobin made of
4 subunits, each with a small haem group and large globin peptide
properties of haem group
- porphyrin ring
- rigid, 2D and highly coloured due to sharing of electrons
- ferrous, so conjugated to Fe2+
which subunits are present in adult haemoglobin
2 alpha and 2 beta
which subunits are present in foetal haemoglobin
2 alpha and 2 gamma
what is the Bohr effect
- increased blood CO2 level decreases affinity
- decreased blood pH level decreases affinity
which forms are CO2 transported in
- dissolved
- carbamino
- HCO3-
how is CO2 transported as HCO3-
- CO2 and H+ converted to H2CO3 by carbonic anhydrase
- H+ binds to Hb and HCO3- leaves through Band 3, a chloride carbonate exchanger
what causes rightward shifts of the haemoglobin dissociation curve
- CO2
- H+
- Cl-
- 2,3-DPG (diphosphoglycerate)
what does 2,3-DPG do
binds to haemoglobin to lower affinity for oxygen
what is foetal hameoglobin’s affinity to 2,3-DPG like
lower than adult, so higher affinity for oxygen
what happens in active muscles
- O2 leaves Hb
- CO2 and H+ bind to Hb
- HCO3- leaves RBC to plasma
- Cl- leaves plasma to RBC
what is breathing controlled by
CO2, O2 and H+
what is the main driver to increase respiratory rate
H+ in cerebrospinal fluid, as CO2 gas enters CSF and acted on by carbonic anhydrase to make H+ and carbonic acid
what is the size of a red blood cell
7 micron diameter
2 micron height
where does erythropoiesis happen after birth
membraneous bone marrow, eg vertebrae
where does erythropoiesis happen before birth
- liver
- spleen
- lymph nodes
- yolk sac
development stages of stem cell differentiation
1) multipotent stem cells
2) multipotent progenitor cells
3) lineage-committed progenitor cells
4) mature cells
what is required for a haematopoietic stem cell to become an erythroblast
erythropoietin
what is required for an erythroblast to become erythrocytes
iron
what is erythropoietin
- a cytokine made in the kidney during hypoxia
- stimulates erythropoiesis
- performance enhancing drug for athletes
what is a reticulocyte
- red blood cell precursor, still contains nucleus and organelles
- lasts for 2 days in the blood
how can reticulocyte count be used
- diagnostic tool in anaemia
- indicator of bone marrow activity
- high levels in haemolytic anaemias
- low levels when erythropoiesis is low
what is methaemoglobinaemia
- Hb cannot transport O2
- ferric haemoglobin Fe3+ rather than ferrous Fe2+
- due to congenital globin mutations, hereditery decrease of NADH, toxic substances
treatment for CO poisoning
95% O2 and 5% CO2
what are polycythaemias
- increase in number of RBCs
- increased viscosity of blood
what is pathological polycythaemia
- polycythaemia vera
- is a neoplasm
- no cure, treat with venesection
- all ages, increases with age
- might be genetic
how is Fe stored intracellularly
- stored as ferritin and haemosiderin
- in reticulo endothelial system
why is vitamin B12 and folic acid important
- essential for forming DNA
- deficiency causes megaloblastic anaemia, fragile cells
- deficiency caused by diet, malabsorption or increased utilisation
- deficiency treated with oral folic acid and intramuscular hydroxocobalamin (B12)
what sort of anaemia is caused by iron deficiency
- hypochromic microcytic anaemia
- cells keep dividing but can’t fill up with Hb
what sort of anaemia is caused by folic acid or B12 deficiency
- megaloblastic anaemia
- cells keep filling up with Hb but can’t divide fast enough
