Components of blood Flashcards
Blood cells are produced in the ____________ by a process known as haematopoiesis (or hematopoiesis or hemopoiesis)
Blood cells are produced in the bone marrow by a process known as haematopoiesis (or hematopoiesis or hemopoiesis)
All the different blood cell types are derived from a relatively small pool of precursor cells called…
Haematopoietic stem cells
What is the site of haematopoiesis in the embryo?
In the yolk sac
From 2 – 5 months gestation, in liver and spleen before finally establishing in the bone marrow from 5 months
What is the site of haematopoiesis at birth?
Mostly marrow, but liver and spleen when needed
As we grow, active marrow sites decrease but retain the ability. Active marrow is confined to ___________ eventually
Axial skeleton (skull, ribs, vertebrae, pelvis and proximal long bones)
Most stem cells sit in a ____________ state
Quiescent
In granulopoiesis, a myeloid lineage committed blast cells divide and mature through a number of intermediate stages (promyelocyte, myelocyte, metamyelocyte) to become a…
Mature neutrophil
An erythroid committed blast cell (____________) which goes through divisions with proliferation and maturation
to eventually form a mature erythrocyte
An erythroid committed blast cell (pronormoblast) which
goes through divisions with proliferation and maturation
to eventually form a mature erythrocyte
How is thrombopoiesis (platelet formation) different from other cells?
When the blast cells divide the cytoplasm does not, so an
increasing number of nuclei accumulate in a single cell
with a very large cytoplasm. The edges of which buds off to
form platelets that are released into the bloodstream.
In Eosinophils the granules take up ______ which is red and acidic
In Eosinophils the granules take up eosin which is red and acidic
In Basophils the granules take up ___________ dyes which are densely blue
In Basophils the granules take up basic (alkali) dyes which are densely blue
In Neutrophils the granules are ______ and ____________
In Neutrophils the granules are fine and ‘neutral’ mix of the two colours
What are the functions of neutrophils?
Phagocytosis
Granule release for elastases and attract other cells via small molecules released
‘Body stress’ eg bacterial infection, trauma, infarction
What are the functions of eosinophils?
Parasitic infections
Hypersensitivity (allergic) reactions
Segmented nucleus
Neutrophils
Bilobed nucleus
Eosinophil
Large deep purple cytoplasmic granules often obscuring the nucleus
Basophil
In basophils, granules contain ___________ and ___________ like molecules
In basophils, granules contain histamine and heparin like molecules
Function of basophils
Mediates hypersensitivity reactions IgE mediated histamine release (?)
Large single nucleus
Monocytes
Monocytes circulate for about a week then enter tissues to become specialised tissue ____________, so much longer lived than ____________
Monocytes circulate for about a week then enter tissues to become specialised tissue macrophages, so much longer lived than neutrophils
Function of monocytes
Clearing debris, engulfing and destroying infective organisms, and presenting antigen to immune cells and releasing signals to attract other cells
How do mature lymphocytes look like?
Small with condensed nucleus and limited cytoplasm
How do acticated/atypical lymphocytes look like?
Large with plentiful blue cytoplasm often extending up to neighbouring red cells on a blood film and with a larger less condensed looking nucleus
Function of lymphocytes
The ‘cognate’ response to infection - the brains of the immune system (different types have different functions)
What does the image show?
Small mature lymphocyte
What does the image show?
Activated lymphocyte
Which cells are frequent/ morphologically remarkable?
The progeny (red cells, neutrophils, eosinophils etc)
Which cells are infrequent/ morphologically unremarkable?
Stem cell, and early committed precursors
How are primitive precursors identified?
Bio-assays - culture marrow in vitro/in vivo and show a colony of a particular cell type when incubated different growth
conditions
Immunophenotyping
In clinical practice what tools do we have to look at the
Automated full blood count analyser
Reviewing a blood film
Bone marrow biopsy from the posterior iliac crest
trephine
Blood is made of _______
Plasma
What does plasma contain?
Red blood cells, white blood cells, platelets and clotting factors, such as fibrinogen
Once the clotting factors are removed from the blood, what is left is called the serum. Serum contains..
Glucose
Electrolytes (sodium and potassium)
Proteins (immunoglobulins (antibodies) and hormones)
Where do blood cells develop?
Bone marrow
Bone marrow is mostly found in…
Pelvis, vertebrae, ribs and sternum
What are the pluripotent haematopoietic stem cells?
Undifferentiated cells that can transform into various blood cells
Pluripotent haematopoietic stem cells can become..
Myeloid stem cells
Lymphoid stem cells
Dendritic cells (via different intermediate stages)
Red blood cells (RBC) develop from ___________, which originate from ___________ stem cells
Red blood cells (RBC) develop from reticulocytes, which originate from myeloid stem cells
Platelets are made by _____________, which develop from the myeloid stem cells
Platelets are made by megakaryocytes, which develop from the myeloid stem cells
What is the lifespan of RBCs?
Four months (120 days)
What is the lifespan of platelets?
Ten days
What is the role of platelets
Clump together (platelet aggregation) and plug gaps where blood clots need to form
Myeloid stem cells become myeloblasts, which can become..
Monocytes then macrophages
Neutrophils
Eosinophils
Mast cells
Basophils
Lymphocytes come from the __________ stem cells and become __ cells or __ cells
Lymphocytes come from the lymphoid stem cells and become B cells or T cells
B lymphocytes (B cells) mature in the bone marrow and differentiate into..
Plasma cells
Memory B cells
B lymphocytes (B cells) mature in the..
Bone marrow
T lymphocytes (T cells) mature in the..
Thymus gland
T lymphocytes (T cells) differentiate into..
CD4 cells (T helper cells)
CD8 cells (cytotoxic T cells)
Define Anisocytosis
Variation in the size of the red blood cells - seen in myelodysplastic syndrome and anaemia (e.g., iron deficiency, pernicious and autoimmune haemolytic anaemia)
Define Target cells
Red blood cells with a central pigmented area surrounded by a pale area, surrounded by a ring of thicker cytoplasm on the outside
Seen in iron deficiency anaemia and post-splenectomy
What are heinz bodies?
Individual blobs seen inside RBCs. These are denatured haemoglobin seen in G6PD deficiency and alpha-thalassaemia.
What are Howell-Jolly bodies?
Individual blobs of DNA material seen inside red blood cells (normally removed by spleen so seen after a splenectomy or with a non-functioning spleen (e.g., sickle cell anaemia)
What are Reticulocytes?
Immature red blood cells - larger than RBCs and still have RNA material. Seen in haemolytic anaemia
What are Schistocytes?
Fragments of red blood cells. Seen in microangiopathic haemolytic anaemia and metallic heart valve replacement
What are Sideroblasts?
Immature red blood cells with a nucleus surrounded by iron blobs. Due to a genetic defect or myelodysplastic syndrome
What are smudge cells?
Ruptured white blood cells - chronic lymphocytic leukaemia
What are Spherocytes?
Sphere-shaped red blood cells without the bi-concave disk shape. Seen in autoimmune haemolytic anaemia or hereditary spherocytosis
What are the most common type of granulocyte?
Neutrophils
Give examples of granulocytes
Neutrophils
Eosinophils
Basophils
Give examples of lymphocytes
B-cells
T-cells
Natural killer cells
What are the types of leukocytes
Granulocytes (neutrophils, eosinophils, and basophils), monocytes, and lymphocytes (T cells and B cells)
What are the components of blood?
What cells undergo Erythropoiesis?
Red cells
What cells undergo Thrombopoiesis?
Platelets
Which cells undergo myelopoiesis/ granulopoiesis?
Neutrophils
Eosinophils
Basophils
Monocytes → macrophages
Which cells undergo lymphopoiesis?
Lymphocytes
Which type of cells undergo self-renewal?
Stem cells (lost in descendents)
Define Differentiation
Descendents commit to one or more lineages
_____________ blood contains a higher proportion of haemopoietic stem cells
Umbilical cord
More primitive progenitors (eg stem cells) are ____________ during steady-state haemopoiesis
Quiescent/dormant
What does myeloid mean?
Marrow
Lineage
Granulocytes and precursors
Where is a bone marrow biopsy taken?
Iliac crest/sternum
What are the compartments of the bone marrow?
Haemopoietic cells
Non-haemopoietic cells
Connective tissue matrix
Vascular elements
Give examples of non-haemopoietic cells
Adipocytes (fat cells)
‘Fibroblasts’ osteoclasts
Osteoblasts
Describe bone marrow vasculature
Arterioles drain into ‘sinuses’ – wide venous vessels, which open into larger central sinuses
These sinuses are larger than the capillary ones and have a discontinuous basement membrane
Explain how mature red cells are released from the marrow
After birth, active red marrow is gradually replaced by __________ marrow so that from age 20, haematopoiesis is concentrated in the __________ skeleton and articular ends of the __________ and __________ bones
After birth, active red marrow is gradually replaced by yellow fat marrow so that from age 20, haematopoiesis is concentrated in the axial skeleton and articular ends of the femoral and humerus bones
What is a normal M:E ratio
Myeloid portion is greater than erythroid portion
When does reversal of M:E ratio occur?
Haemolysis as a compensatory response
What regulates haemopoiesis?
Intrinsic properties of cells (e.g stem cells vs progenitor cells vs mature cells)
Signals from immediate surroundings and the periphery (microenvironmental factors)
Specific anatomical area (‘niche’) for optimal developmental signals
Neutrophil precursor maturation is regulated by…
G-CSF (granulocyte-colony stimulating factor)
____________ regulates growth and development of
megakaryocytyes from their precursors
Thrombopoietin
How do we assess haemopoiesis? (non-lymphoid mature cells)
FBC, cell indices, morphology
Bone marrow examination
How do we assess haemopoiesis? (lymphoid mature cells)
FBC/morphology
Expression of antigens
indicating lineage or stage of development required - immunophenotyping
