PBL 7 - anaemia: types and causes Flashcards
what does blood distribute?
- oxygen and nutrients (removes waste products)
- hormones delivered to target organs
- blood cells and platelets
what does blood regulate?
- body temp
- pH
- solutes
- restricts osmosis into tissues
what does blood protect against?
- blood/fluid loss via haemostasis (coagulation)
- infection via contribution to inflammatory and immune responses
if the cellular components of blood are removed, what remains?
plasma
what is the buffy coat?
everything but the RBCs which will centrifuge out at this layer — WBCs + platelets
what is roughly the circulating volume of blood?
4-5l
where are the remnants of RBCs broken down?
liver and spleen
describe production of EPO
produced by kidney in response to low O2 levels
how can acute kidney disease affect EPO production?
often have anaemia with acute kidney disease — reduced production of EPO
how does testosterone affect EPO production?
enhances production
how many haem groups are there per Hb molecule?
4
how many iron atoms are there in 1 molecule of Hb?
4
each Hb can bind how many molecules of O2?
4
Hb holds iron in what form?
ferrous form = Fe++
what does proliferation of RBC precursors require?
- DNA synthesis (ie. precursors have a nucleus)
- protein synthesis (synthesis of some amino acids)
what 2 B-complex vitamins play a critical role in RBCs?
- folate (50-100ug/day) = vitamin B9 — required for synthesis of purines and pyrimidines
- vitamin B12 (approx 3ug/day) — required for synthesis of some amino acids
what is anaemia?
= reduction in Hb conc
- men < 13.5 g/dl
- women < 11.5 g/dl
what are some symptoms of anaemia?
- breathlessness
- fatigue
- palpitations
- related to cause
what are some signs of anaemia?
- pallor (pale) — not always
- related to cause — eg. jaundice if liver disease, cachexic if malnourished/cancer, sallow complexion if renal disease due to increased urea
what are the 2 different classifications of anaemia?
based on cause:
- failure of production
- defective red cells
- loss/destruction of red cells
based on red cell size:
- macrocytic
- normocytic
- microcytic
impaired vs. excessive erythrocyte production/destruction
- impaired erythrocyte production
- caused by deficiencies (diet)
- not caused by deficiencies - excessive erythrocyte destruction
- extracorpuscular defects, usually acquired eg.
autoimmune disease
- intracorpuscular defects, usually inherited
what is looked at in a FBC for anaemia?
- normal ranges change with age, sex
- look at MCV (mean cell volume)
- look at other aspects of the FBC; WCC and differential and platelets
- blood film comments
- compare with previous results, if available
what are the 2 different types of blood loss that can lead to anaemia?
- acute = dilution to maintain circulatory volume
- chronic = slow and ongoing but profound — peptic ulcers, menorrhagia, piles, worms etc.
what deficiencies can cause impaired erythrocyte production?
- iron
- vitamin B12
- folate
- protein — malnutrition, liver disease, malabsorption, carcinoma
- vitamin C (vital for protein synthesis)