8 Heamatology Flashcards
What is haematopeoisis
The production of all elements in the blood including RBCs WBCs and platelets
What is the composition of blood?
- 55% plasma
- 45% formed elements
- less than 1 % WBCs and platelets
What is the constitution of plasma?
- 92% water
- 7% plasma proteins
- 1% other dissolved substances
What are the plasma proteins?
Albumin
globulin
regulatory proteins
fibrinogen
Function of plasma:
Transport:
- heat
- gases
- nutrients
- waste
- formed elements
- inorganic and organic elements
Haematopeisis: lymphocytes
Starts with a haemocytoblast (multipotent stem cell) –> common lymphoid proginetor –> small lymphocyte –> T cell/ Bcell
B call –> plasma cell
common proginetor –> natural killer cell (large granular lymphocyte)
Haematopeisis: platelets
haemocytoblast (multi potent cell) –> common myeloid proginetor –> megakaryocte –> thrombocyte
Haematopeisis: erythrocyte
Haemocytoblast –> common myeloid proginetor –> mast cell/erythrocyte
Haematopoeisis: macrophage
Heamocytoblast –> common myeloid proginetor –> myeloblast –> neutrophil/ basophil/ eosinophil/ monocyte
monocyte –> macrophage
Erythropoeisis:
Haemoblastocyte –> proerythroblast (committed cell) –> early/late erythroblast –> nomoblast –> reticulocyte –> erythrocyte
Name the phases of erthyropoeisis:
1 ribosomal synthesis - early erthyroblast
2 haemoglobin accumulation - late erythroblast
3 nuclear expulsion - nomoblast
Where are RBCs made in adults?
bone marrow –> red bone marrow (skull, ribs, spine) except in emergencies
Where are RBCs made in foetuses?
Yolk sac –> liver, spleen –> bone marrow
Which phases are most of the haemoglobin made?
65% in the erythroblast phase
35% reticulocyte phase (useful in anaemia)
what is a ___blast
a cell which is not yet fully mature
How many RBCs do we produce per second?
2-3 million
Structure of RBCs
- biconcave disc shape
- very flexible and
- 7-8 micrometers diameter
- 2-3 micrometers width
- no organelles or nucleus so can hold more haemoglobin
- 120 lifespan coz can’t repair themselves
- get less flexy and more fragile as life goes on
Where are RBCs broken down
Liver
What breaks RBCs down?
Macrophages
Explain the process of breaking down RBCs
- macrophage engulfs and separates the contents into
- haem
- globin
What happens to haem when RBCs are broken down
- separated into bilirubin which is combined with albumin and taken to the liver where it mixes with bile and can be excreted
- and iron which is transported back to bone marrow in blood combined with transferrin or kept in the liver as ferritin
What happens to globin when RBCs are broken down?
It is broken down into amino acids which are used to make more globin or other proteins
What happens when we have an excess of bilirubin?
We get jaundis and go yellow.
How is the level of RBCs controlled
Homeostasis measuring the amount of O2 in the blood
What is a lack of O2 in the blood called
Hypoxemia
What is too much O2 in the blood from?
Hypoxia
What happens during hypoxemia
The kidneys are stimulated to produce more erythropoeitin
Where is erythropoeitin produced?
The kidneys
What causes hypoxemia (4)?
smoking (CO competes)
blood loss
high altitude
increase in exercise
What are the normal levels of haemoglobin in the blood?
W: 12-16 g/dl
M: 13-17 g/dl
Av. 15 g/dl
How many haemoglobin molecules are there per RBC?
280 million
How many molecules of O2 can each haem group hold?
4
Structure of haemoglobin:
4 sub units
-2 alpha
-2 beta
each unit consists of a haem molecule bound to a a long polypeptide chain (globin)
-Fe2+ ion in the middle
-ion can bind with one molecule of oxygen
Which gases does haemoglobin carry?
O2
CO2
CO
H+
Anaemia is classified by:
the below accepted normal levels of haemoglobin in the blood (12-13.5 g/dl)
How prevalent is anaemia?
1/3 of the worlds population suffer from it
Causes of anaemia:
increased RBC destruction
Reduced RBC production
Blood loss
What happens in iron deficient anaemia:
- microcytic eryhtrocytes form
- less mean cell volume
- less haemoglobin means paler cells
What are the causes of iron deficient anaemia?
anything that puts strain on the body
- malnutrition
- malabsorption
- heavy periods
- preganacy
What happens in vitamin B12 deficient anaemia?
- Not enough vitamin B12 produces not fully functional RBCs
- if lack of intrinsic factor production its called pernicious anaemia
- IF allows us to absorb vit B12 form our diet
- only treatment is to give an intramuscular injection of vit B12 that bypasses the stomach
- Macrocytic RBCs form but they’re not full functional
Folate deficiency and anaemia:
-very similar to B12 deficiency
-also causes macrocytic RBCs
causes:
-elderly
-dietary deficiency
-pregnancy
Sickle cell anaemia:
where is it prevalent and what happens?
- prevalent in africa and west india
- point mutation causes haemoglobin to be transcribed as haemoglobin s
- causes sickle shaped cells
- get stuck in vessels
- no cure
- hereditary
Thalassaemia:
where is it prevalent and what happens?
Problem with globin chain production causes less RBCs to be made and reduces the blood cells carrying capacity
prevalent in Mediterranean and middle/eastern asia
