Blood I Flashcards
function of blood
- transport: O2, nutrients, CO2 and waste products
- immune response
what is the composition of blood
plasma (55%)
cells (40-45%)
when does haemopoisis begin
then 6 wks-6 months
6 months-birth
adult life
in yolk sac at 3rd week of gestation
6 wks–6 mo: liver, spleen (extramedullar)
6 mo–birth: bone marrow taking over (medullary)
In adult life: bone marrow
how do mature cells form
pluripotent stem cells–> myeloid or lymphoid cells–> committed stem cells–> earliest recognisable precursors–> mature cells
how is MCV mean cell volume calculated
PCV/RBC count
how is mean cell Hb calculated
Hb (g/dl)/RBC count
how is mean cell Hb conc calculated
Hb g/dl/ PCV
what are the essential diatary constituents of blood
- iron
- vit B12
- folic acid
what is anaemia
haemiglobin lower than ref level for age and gender
reduction in red cell mass
classified in terms of RED CELL INDICES (MCV)
what are the 3 major types of anaemia
- hypochromic microcytic with low MCV
- normochromic normocytic with a normal MCV
- macrocytic with a high MCV
what are the pathological consequences of anaemia
tissue hypoxia
what are the clinical manifestations of anaemia
- can be asymptomatic
- fatugue
- headaches
- faintness
- pallor of conjuctiva
what is anisocytosis in anaemia
variation in size
eg low VitB12
what is poikilocytosis
variation in shape
eg sickle cell
what is anisochromasia
variation in haemoglobinisation
eg low Fe
what are the causes of anaemia
- dec production
(suppressed proliferation, defective maturation) - inc destruction/loss
(haemorrhage, haemolysis)
describe Fe deficiency
- causes microcytic and hypochromic anaemia
- most common cause of anaemia
- iron status controlled by absorption
- stored ferritin and haemosiderin
what causes Fe deficiency
- inc demands
- chronic blood loss
- poor diet
- malabsorption
how to treat Fe deficient anaemia
- find and treat underlying cause
- Fe to correct anaemia
- monitored by RETICULOCYTE count and Hb
- oral Fe
what happens if Fe therapy doesn’t work
what could be the cause
- non-compliance
- incorrect diagnosis
- mixed deficiency eg thalassamia
- chronic inflammation eg TB, malaria INFECTIOUS, and rheumatoid arthiritis
- malignant disease eg carcinoma, sarcoma, lymphoma
what is megaloblastic anaemia
- eg macrocytic, normo/hypochromic
- characterised by megaloblasts in bone marrow eg erythroblasts with delayed nucleus formation
- large oval RBCs
- hypersegmented neutrophils
what are the causes of megaloblastic
- deficiency of VitB12 and folate
- abnormal metabolism of B12 and folate
- other defects of DNA synthesis
dietary folate i sessential for what
DNA synthesis
as it provides methylation to form DNA
where is B12
- meat
- fish
- dairy produce
- not in plants
where is B12 absorbed
in terminal ileum, Intrinsic Factor req
what is the function of B12
methylation for DNA synth
what are the causes of B12 deficiency
- low dietary inate
- malabsoption: gastric (pernicious anaemia, congenital lack of IF, gastrectomy)
- intestinal: Crohn’s, blind loop syndrome, ileal resection
folate is from where
- meat
- greens
(present as polyglutamates)
how is folate metabolised
converted to MONOGLUTAMATE during absorption
what are the causes of folate deficiency
- nutritional (poor diet, overcooking food)
- malabsorption (tropical sprue, coeliac, Crohn’s)
- excess utilisation (pregnancy, lactation, malignancy, haemolytic anaemia)
- drugs (alcohol, anti-convulsants)
