anaemia Flashcards
anaemia definition
condition in which the number of red blood cells or their oxygen carrying capacity is insufficient to meet physiological needs which vary by age, sex, altitude, smoking and pregnancy status
what is the name of the stem cells that make red blood cells
haemotopoetic stem cells in the bone marrow in the process of haematopoeisis.
explain the process of haematopoeisis
begins with a multipotent haematopoetic stem cell, develops into a common lymphoid progenitor which can differentiate into t cell, b cell or NK cell (natural killer). if the hps cell develops into a common myeloid progenitor then it can diffrentiate into erythrocytes, mast cells or mega karyocytes which can diffrentiate into platelets, or the common myeloid progenitor can differentiate into neutrophil, monocyte or osteoclast.
what is the daily production of red blood cells
200 billion
what is the lifespan of a red blood cell
120 days +- 20 days
how many red blood cells are destroyed per second
2.5 million red blood cells
what are early red blood cells or new red blood cells called
reticulocytes
no nucleus but has rna
how does the reticulocyte turn into a mature red blood cell
loses rna.
has no rna and no nucleus
what happens in the bone marrow stage of rbc production
red blood cell precursors begin to mature
briefly outline how erythropoiesis occurs
in the bone marrow, haematopatic stem cells produce RBC. the red blood cell precursors begin to mature causing a reticulocyte to form which is a new red blood cell. although it has no nucleus, it still has rna. as the reticulocyte matures into a red blood cell, it loses its rna.
what is the major function of a red blood cell
oxygen carrier, provides oxygen to tissues.
explain how red blood cells act as oxygen carriers
red blood cell contains lots of haemoglobin protein which allows oxygen molecules to bind in the lungs, this blood then travels to tissues and releases oxygen into tissue cells , oxyhaemoglobin unloads the oxygen at the tissues.
describe the major protein haemoglobin
tetramer of 4 globin folded proteins
2 alpha chains and 2 beta chains
fe2+ haem groups
describe haem group
contains fe iron
oxygen binding capacity
what does DO2 represent in the oxygen delivery equation
the oxygen delivery
what does Q represent in the oxygen delivery equation
cardiac output
what does HB represent in the oxygen delivery equation
haemoglobin
what does saO2 represent in the oxygen delivery equation
arterial oxygen saturation
what does PaO2 represent in the oxygen delivery equation
amount of dissolved oxygen in the blood
what is the oxygen delivery equation
DO2= Q x (hbxSaO2) x 1.34 + (pao2 x 0.003)
how is erythropoiesis regulated
1) low oxygen blood level is detected
2) stimulus causes kidneys to increase production of EPO (erythropoietin)
3) erythropoietin hormone released by kidneys stimulates RBC production
3) stem cells increase red blood cell production
4) oxygen blood level returns to normal
5) normal oxygen levels in blood
6) stimulus is resolved
explain erythropoiesis regulation including jak 2
EPO binds to receptor on bone marrow erythroid progenitor, the binding of the receptor to the epo induces conformational changes in jak 2 that cause stats, mapk, akt/p13k. this occurs on the extracellular membrane cytoplasm
what happens at the end of the life cycle of the red blood cells
1) red blood cell death and phagocytosis
2) globin is broken down into amino acids that can be reused for protein synthesis
3) the haem in the red blood cell can be broken down into billiverdin which is eventually broken down into billirubin which is secreted in the gut and some of it is absorbed.
where are red cells produced
in the bone marrow
what is the main function of a red blood cell
transport oxygen to the tissues
what stimulates erythropoietin by the kidneys to stimulate red cell production
hypoxia- low oxygen levels in the blood
how many days do red blood cells live
120 days and are recycled by the reticulo endothelial system.
what procedure can we carry out to diagnose anaemia in the lab
venepuncture and then passing the sample through the automated blood count analyser
what does a full blood count show us or tell us
-haemoglobin
-white cell count
-platelet count
what method is used to directly measure haemoglobin
photometric method
expressed as a concentration g/L
what are red cell indices
mean cell volume
red cell distribution width rdw
packed cell volume
red cell count
reticulocyte count
what is mean cell volume if measured directly expressed as
FL 10^-15
what is the reference range for mean cell volume
80-99fl
what mean cell volume indicates microcytic cells
MCV<80fl
what is a normal mcv mean cell volume
80-100fl
what mean cell volume is macrocytic
mcv>100fl
what pathway follows if the mean cell volume is less than 80fl (microcytic)
-next step is to check ferritin levels (ferritin is a protein which carries iron)
if ferritin is too low than this indicates iron deficiency anaemia- mean cell volume low but rdw high.
if mean cell volume is lower than 80fl and ferritin levels are high than indicates thalassemia
thalassemia, inherited anaemia normal rdw normal distribution width
when the mean cell volume is normal 80-100 what is the next steps
to check reticulocyte count
if cell is normocytic and reticulocyte count is lower than what is the anaemia diagnosis
anaemia of chronic disease marrow hypoplasia
if reticulocyte count is higher after determining cell is normocytic what is the next test
if alot of haemolysis, conduct a DAT test if DAT test positive than autoimmune haemolysis if DAT test negative- hbss g6pd mechanical
if cells are macrocytic, the mcv is higher than 100fl than what is the next step
test for b12 folate and if b12 low than diagnose as b12 folate deficiency anaemia.
if b12 folate is normal or high than diagnosis is active haemolysis so conduct DAT tests to determine whether anaemia is autoimmune or g6pd anaemia.
what is the reference range for red cell distribution width
11-15%
what is anaemia diagnosed by having
hb levels less than lower limit of reference range
what can we look at to determine cause of anaemia
blood film, fbc parameters
what does a normal rdw indicate
that cells are more or less uniform size
anaemia is a lack of what
haemoglobin
most common worldwide anaemias
iron deficiency thalassemia
what are the two main mechanisms of anaemia
-insufficient production or excessive loss of red blood cells
-laboratory investigations can help tell them apart
what is g6pd deficiency
glucose 6 phosphate dehydrogenase deficiency showing irregularly contracted cells. mutation in enzyme pivotal in krebs cycle so when theres oxidative stress triggers such as drugs, cells cannot cope and haemolyse.
signs of iron deficiency
spooning of nails
pallor
conjunctivitis
angular cholitis
what are some signs and symptoms of severe anaemia
-angina chest pain
-heart attack
-fainting
what are some respiratory symptoms of anaemia
shortness of breath
what are some blood vessel signs of anaemia
low blood pressure
what is a sign of anaemia related to spleen
enlargement of spleen
what is a intestinal sign of anaemia
changed stool colour
what are some muscular symptoms of anaemia
weakness
what are some skin symptoms of anaemia
pallor
coldness
yellowing
eyes yellow as well
what are some heart related symptoms and signs of anaemia
palpitations
rapid heart rate
chest pain
angina heart attack
what are some central symptoms of anaemia
fainting
dizziness
fatigue
