RBC Creatine Flashcards
Give me some structural features of RBC
Biconcave
no nucleus
high surface area/volume
maintains membrane integrity and prevents oxidation
What are the main functions of RBC
O2 and CO2 transport, acid/base balance
Tell me about stem cells in embryonic development
stem cells form blood islands in yolk sac
cells migrate to the liver then spleen then bone marrow
at birth widely distributed then retreating to axial skeleton by adulthood
Bone marrow stroma
fat cells
macrophages
fibroblasts
endothelium
What are the growth factors that drive maturation
- interleukin 3
- erythropoietin
- androgens
- thyroxine
- growth hormone
Reticulocytes
remnants of mRNA left once the nucleus of a maturing RBC has been extruded. Removed by spleen in 1-2 days.
What is reticulocytes used for:
useful for measure of marrow response to anaemia or treatment
What are reticulocytes stained by
methylene blue on a slide or automated count
how much iron does a normal adult have
3000-5000mg 2/3 is Hb
Where is fe +++ transported
duodenal enterocytes
What chemical regulates iron absorption and release from macrophages
Hepcidin = increased during an inflammatory response so their is less available iron
What are the different ways of iron loss
menstrual loss minor trauma GI Blood sampling Very small amounts in urine and skin shedding
What is the role of trasnferrin
transport/recycle of iron molecules, these receptors are increased in iron deficiency
what is ferritin
insoluble storage form of iron
Where is folic acid absorbed
upper small bowel
What is the role of the intrinsic factor
Gastric parietal cells produce it and it binds to B12
Where is B12 absorbed
terminal ileum
What are antibodies to intrinsic factors are associated with
gastric atrophy
B12 and Folic acid
gets folic acid into the cell in a functioning form
allows production of thymidine (1 of 4 bases) from uridine (in RNA not DNA)
we eat 5 methyl tetradrofolate, B12 changes this to THF by stripping off methyl group (co-factor)
what is erythropoetin triggered by
tissue hypoxia = at low 02 levels mRNA for epo Is increased
high altitude
epo producing tumours
spectrin
two forms wound together and anchored to the cell membrane alpha and beta, provides its resilience, gives its ability to spring back once squeezed through capillaries
Haem O2 binding
one O2 per globin chain (4 chains)
What is haemoglobin composed of
2- alpha chains (zeta then to alpha)
2- beta chains (epsilon then gamma (child) then delta then beta
What is Thalassaemia
an inherited defect in globin chain
sickle cell disease
one amino acid change in beta chain
What is the role of the glycotic pathway ending with lactate and pyruvate
maintain membrane integrity
Prevent oxidation of enzymes and Fe++
Maintain gradients of K+ and Ca ++
What kind of enzymes can cause anaemia
pyruvate kinase by haemolysis - increase rate RBC breakdown
What factors will cause increased O2 delivery to tissues
Acidosis and increased temperature
intermediate stage in glycoloysis
2,3 DPG causes more 02 to be released as it wedges open the chains and releases O2, increased when excessing/anaemia and high altitude
What is myoglobin
store of O2 in skeletal muscle for immediate use
Tell me about the acid-base balance
Regulates free H+ ions in body fluids
pH normally 7.35 to 7.45
Whats the equation for the buffer system (60%)
CO2 + H2O (Carbonic Anhydrase acts as catalyst) >
H2CO3
>
H+ + HCO3-
buffer system for 30% capacity
H+ combines with Hb after loss of 02
low pH decreases affinity for 02
CO2 + Hb > HbCOO- + H+
What happens as RBC age
membrane more rigid
loss of glycolytic enzymes
neoantigens exposed on cells surface
Tell me about the recycling of RBC
- Haptoglobin mops up free Hb
- cleared by liver
- Globing chains broken up into amino acids
- Iron bound to transferrin and returned to macrophages
- porphyrin ring > bilirubin
- bound to albumin
- conjugated to glucuronice
- excreted in bile
