Haemotology - RBCs Flashcards
avg abult blood volume
5L
~7% of your weight
components of blood
45% cells (formed elements):
RBCs
WBCs
platelets
(46-63%) plasma
plasma composition
92% water
plasma proteins 7%
other solutes 1% - electrolytes, org nutrients, waste
examples of plasma proteins
albumin
globulin
fibrinogen (coagulation protein)
regulatory proteins e.g. hormones
in a centrifuged sample of blood, what does the WBC/platelets layer look like?
very thin layer between plasma and RBCs
in healthy person can see less
increased visibility in unhealthy person
what does blood transport and hoe does it defend
transports:
gases o2 and co2
nutrients
excretory products
temperature control (alongside blood vessels via vasodil and vasoconst)
defense:
antibodies, wbc
clotting factors (aka haemostatic process)
what is the stem cell that can differentiate into any blood cell
multipotential haematopoietic stem cell (haemocytoblast)
which type of cell produces RBCs, platelets and 4 types of WBCs?
common myeloid progenitor
which type of cell produces lymphocytes?
common lymphoid progenitor
whats the name of the immature cell found in bone marrow that forms 4 key WBCs
myeloblast
what is the process of blood cell formation called
haematopoiesis
see onenot for detailed diagram and learn it pls xoxo
what is the name of the commited cell in erythropoises
proerythroblast
name the order of cell types in erythropoieses
haemocytoblast -> proerythroblast -> early erythroblast -> late erythroblast -> normoblast -> reticulocyte -> erythrocyte
see diagram in onenote i made it all pretty
requirements for erythropoiesis
erythropoietin
iron
vit B12
folic acid (B9)
intrinsic factor (helps in absorption of B12)
amino acids (for globin production)
RBC structure
~7.5micrometres (caps are a lot smaller so they must be flexible)
deform readily, highly flex
no organelles or nucleus
life span = 121 days
breakdown process of a RBC
macrophages break down the aged RBCs
spilts Hb into heme and globin
heme turns into Bilirubin + iron
Bilirubin which is combined with serum albumin
transported to liver
secreted into bile
Iron combined with transferrin(transport protein)
stored as ferritin(storage protein) in the liver and spleen
the globin transormed back in into amino acids
see one note for diagram
what are some causes of hypoxia
- inc in excercise
- high altitude
- smoking
- bleeding
describe erythrocyte homeostasis
- low o2 blood levels (stimulus)
- picked up by blood vessels in kidneys (receptor)
3 kidneys inc production of erythropoietin - stem cells increase RBC production
- o2 blood levels return to normal
what stage does Hb synthesis start
in the proerythroblast
65% is made at erythroblast
35% is made at reticulocyte stage (after nucleus is gone)
how many on avg Hb molecules per RBC?
280million~
how much (in g/dL) Hb is in blood, females and males
F= 12-16 g/dL
M= 13.5-12.5g/dL
structure of Hb protein
4 subunits (2 alpha 2 beta)
each subunit has a haem
which is bound to globin (long polypeptide chain)
in middle of Haem group is ferrous iron atom (Fe2+)
this atom can bind (reversibly) with one molecule of O2
def of anaemia
Hb conc in whole blood below the accepted normal range
men - less than 13.5g/dL
women - less than 12g/dL
causes of anaemia
decreased RBC production - can happen if required units not there (e.g. less B12, folic acid etc)
increased RBC destruction - haemolytic anaemia (RBCs break down faster than made, can be casued by autoimmune disease, bone marrow disease etc.)
blood loss - acute (ie in an accident) or chronic (ie stomach ulcers, endometriosis, cancer etc)
iron deficiency anaemia key points
most common anaemia
hypochromic (paler coloured cells)
microcytic RBCs (smaller diameter)
decreased mean volume (MCV)
causes -
pregnancy,
bleeding from GI tract (ulcer, malignancy etc), malabsorption,
menorrhagia (period),
malnutrition
diagnosis of iron deficiency not adequate - always seek cause
megaloblastic anaemia
vit B12 deficiency or folate deficiency (affects the way in which cells mature - hence MEGAloBLASTic cuz theyre large and immature)
macrocytic cells (larger in diameter)
reduced Hb conc.
increased mean cell volume (MCV)
hypersegmented neutrophils (can see in blood smear under microscope)
megaloblastic anaemia: as folate deficiency
causes macrocytic anaemia
the reason theyre big is cuz they dont mature properly
and cells are unable to divide without folate
causes - pregnancxy, elderly, diet
megaloblastic anaemia: as B12 deficiency
to absorb B12, we need intrinsic factor (IF)
usually secreted by stomach
cuases:
lack of IF - PERNICIOUS ANAEMIA cuz lack of B12
Crohn’s, coeliac disease - affect absorption too
treatment: Intramuscular B12 inejctions
used to be fatal cuz people didnt know that giving B12 orally wasn’t helping
sickle cell anaemia
hereditary (african, west indian communities have more)
abrnormal Hb structure
causes sickle shaped cells
RBCs get stuck in blood vessels or
RBCs die prematurely
thalassaemias
hereditary (mediterranean, middle/far eastern)
Abnormal Hb production - alpha and beta thalassaemias
