Lecture 14- Haematology Lecture 2 Flashcards
What are the 3 types of leukocytes (white blood cells)?
3 main types:
* Granulocytes
* Lymphocytes
* Monocytes & Macrophages
What are neutrophils and what are their characteristics?
Neutrophils (make up 50-72% Leukocytes)
- Life span: 6h to a few days
- Most numerous leukocyte
- Defence against bacteria (mainly) and some fungi
- They are active phagocytes, engulfing bacteria & destroy them using
enzymes stored within lysosomes - Produce reactive oxygen species such as hydrogen peroxide to
degrade the pathogen.
What are eosinophils? What are their characteristics?
Eosinophils (2-4% Leukocytes)
- Life span: ~5 days
- Large coarse granules that stain red with acid dyes, filled with a
unique variety of digestive enzymes - Lead attack against parasitic worms that are too large to be
phagocytosed - When they encounter a worm many cells gather around it and
release their cytoplasmic granules onto the parasite surface,
digesting it. - Differentiate from myeloid progenitor cell.
What are basophils and what are their characteristics?
Basophils (0.5-1% Leukocytes)
* Life span: a few hours – a few days
* Large coarse granules that stain purple/black with basic dyes
pack the cytoplasm
* Filled with histamine (an inflammatory mediator) that acts as a vasodilator
What is the function of erythrocytes? And what are their characteristics?
Erythrocytes (44% whole blood) (RBCs)
* Also referred to as red blood cells
* The most abundant cells in the blood (4-5 x 1012 per litre)
* Physical properties:
* Small (7.5-8μm diameter)
* biconcave disc
* lacking a nucleus and most organelles
* Lifespan of 120 days
* Function: transport O2
and CO2
, facilitated by haemoglobin
* To maintain equilibrium ~1% must be replaced daily => 1010/hour
What is erythropoiesis? Why is it important?
- Process of generating mature erythrocytes
(red blood cells) - Regulated in a feedback process by the
hormone erythropoietin (EPO). - Cytokines, growth factors and hormones
influence erythroid proliferation,
differentiation and maturation
What happens when erythrocytes die?
they live for 120 days then-
Erythrocyte breakdown
* Proteases degrade haemoglobin in lysosomes of macrophages.
* Globin is broken down into amino acids and re-used.
* Haem is degraded into bilirubin, which is then metabolised and
bile acids are used to make it soluble.
* Fe2+ is recycled: It binds transferrin to be transported to the
bone marrow for new erythrocyte synthesis.
* 10% of the old cells haemolysed in the circulation, engulfed by
circulating monocytes
How many steps are involved in the breakdown of an erythrocyte? Go through all the steps
Erythrocyte breakdown
* Proteases degrade haemoglobin in lysosomes of macrophages.
* Globin is broken down into amino acids and re-used.
* Haem is degraded into bilirubin, which is then metabolised and
bile acids are used to make it soluble.
* Fe2+ is recycled: It binds transferrin to be transported to the
bone marrow for new erythrocyte synthesis.
* 10% of the old cells haemolysed in the circulation, engulfed by
circulating monocytes
What is haemolysis?
Hemolysis is the process by which red blood cells (erythrocytes) are destroyed or ruptured, leading to the release of their contents, including hemoglobin, into the surrounding fluid (plasma or serum).
How do we check if someone has enough erythrocytes? What is the normal amount of HCT for men and women?
Haematocrit
* Useful to estimate proportion of
erythrocytes in a blood sample to
indicate O2
-carrying capability
* Haematocrit (Hct):
* proportion of blood made up
by cells (erythrocytes AND
leukocytes).
* given as a ratio
* also known as packed cell
volume (PCV)
Normal Hct: 0.47 (0.42-0.54) males
0.42 (0.37-0.47) females
what are Eosinophils?
Eosinophils (2-4% Leukocytes)
* Life span: ~5 days
* Large coarse granules that stain red with acid dyes, filled with a
unique variety of digestive enzymes
* Lead attack against parasitic worms that are too large to be
phagocytosed
* When they encounter a worm many cells gather around it and
release their cytoplasmic granules onto the parasite surface,
digesting it.
* Differentiate from myeloid progenitor cell.
what are mast cells
Mast cells <0.2% Leukocytes
* Generated in the bone marrow and terminal differentiation &
proliferation occurs in the target tissue.
* Important role in allergic reactions and inflammation, involving the
release of histamine from their secretory granules
* Important in defence against parasites because they recruit other
types of leukocytes
* Involved in angiogenesis
what are monocytes and macrophages
Monocytes and Macrophages
(3-8% Leukocytes)
* Life span: months
* Monocytes present in circulation for 1-3 days
* First line of defence against viruses
* Also phagocytose dead cells and bacteria
* Circulating monocytes are precursors of tissue
macrophages (which are actively phagocytic)
* Important in the inflammatory response
what are lymphocytes?
Lymphocytes (20-25% Leukocytes)
* Large nucleus (dark), small amount of cytoplasm (blue).
* 6-14μm diameter
* Most circulate in lymphoid tissues and lymph, only in blood
for a few hours at a time.
* 3 types:
* B-Lymphocytes (B-cells)
* T-lymphocytes (T-cells)
* Natural Killer cells (NK cells)
what are b-lymphocytes?
B-Lymphocytes
➢Main role to destroy bacteria and inactivating their toxins
➢Differentiate into plasma cells that secrete antibodies when
stimulated by antigen
* Antibodies are immunoglobulins that act against antigens by:
* Agglutination
* Opsonisation
