Constituents of blood and haemopoiesis Flashcards
What is blood?
A specialised fluid (technically a tissue) composed of cells suspended in a liquid know as plasma
What are three broad categories of cells in blood
red blood cells
white blood cells
platelets
What are the types of white cells
Monocytes Neutrophils Eosinophils Basphils Lymphocytes NK cells
What are the three main functions of blood
Fight infection - white cells
Transport oxygen- red cells
Prevent bleeding- platelets
What is haemopoiesis?
the production of blood cells
What is the derivative cell of all blood cells
Pluripotent stem cells
Where does haematopoises occur in an adult
Bone marrow - in the skull, ribs, sternum, pelvis and proximal femur
Where does haematopoiesis occur in an embryo
Yolk sac then liver
3-7 months = spleen
Where does haematopoiesis occur at birth
Mostly bone marrow, liver and spleen
What happens to the bone marrow from birth to adulthood
Number of active sites in bone marrow which produce blood cells decreases but retain ability to undergo haematopoiesis
What happens to stem cells so that they can make blood
They proliferate and differentiate into the different types of specialised blood cells in the ‘haematopoietic tree’
Stem cells must self renew also
At what stage of the haemopoietic tree can stem cells no longer renew back into stem cells and they instead must differentiate into blood cells
When they are multipotent progenitors
What are the stages f erythropoiesis
Pronormoblast Basophilic/early normoblast Polychromatophilic/intermediate normoblast Othochromatic/late normoblast Reticulocyte Mature red cell/erythrocyte
How do platelets form
By budding off the membrane of giant cells (megakaryocytes_
What are granulocytes
A group of white blood cells characterised by the presence of granules in their cytoplasm. Named in accordance with their uptake of stains eg eosin and basic dyes
Name the granulocytes
Eosinophils
Basophils
Neutrophils
(Mast cells)
What is the morphology of a neutrophil
Segmented nucleus (polymorph) Neutral staining granules
What is the function of neutrophils
Short life in circulation - move in to tissues in response to appropriate signal Phagocytose invaders Die in the process Kill with granule contents Attract other immune cells
What increases the level of neutrophils in the blood
Infection
Trauma
Infarction
What is the morphology of eosinphils
Usually bi lobed
Bright orange/red granules
What is the function of eosinophils
Fight parasitic infction
Hypersensitivity eg in asthma, atopic rhinitis and allergic reactions
What is the structure of basophils
Infrequent in circulation
Large deep purple granules obscuring nucleus
What is the function of a basophil
Circulating version of a mast cell.
Hypersensitivity
Fc receptors bind IgE
Contain histamine in their granules
What is the structure of monocytes
Large single nucleus which stains faintly, often vacuolated
What is the function of monocytes
Circulate for a week and enter tissues to become macrophages Phagocytose invades Present antigen to lymphocytes Attract other cells Longer lived than neutrophils
What is the structure of lymphocytes
Mature- small with condensed nucleus and rim of cytoplasm
Activated- large with plentiful blue cytoplasm extending round neighbouring red cells on the film, nucleus more ‘open’ structure
What is the function of lymphocytes
Lots of types - B cells, T cells, NK cells
Cognate response to INFECTION
Brain of the immune system
