Haemopoiesis and lymph Flashcards
Define haemopoiesis and what does it encompass
- the formation of red cells, platelets, white cells
Includes
- erythropoiesis
- thrombopoiesis
- leucopoiesis
- granulopoiesis
What is the first cell type to reduce in numbers when haemopoeisis is halted?
- neutrophils
What are platelets formed from?
- budding of the cytoplasm of megakarocyte
- under the influence of thrombopoieitn (TPO)
What is a myelocyte
- nucleated precursor between neutrophil and myeloblast
What is a function of a haematopoetic stem cell
- able to self renew
What are the embryonic sites of haemopoeisis?
- originally in the mesoderm at week 5 to week 10
- yolk sac
- liver
- bone marrow by week 16
Where does haemaopoesis occur in the adult?
- axial skeleton
What occurs to the sites of haemopoeisis as you age?
- they are replaced with fat
Where is bone marrow sampled from in the adult?
- iliac crest
- sternum
Where is the bone marrow sampled from in a young child?
- tibia
What does the bone marrow contain?
- cellular components
- connective tissue matrix
- vasculature elements
What is the blood supply to the bone marrow?
- nutrient artery
- periosteal artery
Where does blood drain from the bone marrow into?
- venous sinuses
Describe the histology of bone marrow sinusoids
- discontinous capillaries
- cells and nutrients can pass through
Explain the myeloid:erythroid ratio
- describes immature to mature cell production
- erythroid ratio increases in blood loss
- normal = 1.5:1 - 3.3:1
What are the 3 main factors that influence haemopoiesis
- intrinsic properties
- signals from immediate surrounds/periphery
- anatomical areas
What is the main haempoetic growth factor?
- colony stimulating factors (CSF)
How is mature non-lymphoid cells assessed?
- routine bloods
- bone marrow sampling
What is immunophenotyping?
- investigation by expression of antigens on lymphoid cells
- marked with different fluorescent dyes
- with flow cytomere % of cell types are calculated
How is precursor haemopoetic cells investigated?
- immunophenotyping
- clongenic expression
- animal models
What antigen is expressed on T lymphocytes?
- CD3 antigen
What antigen is expressed of haemopoetic stem cells?
- CD34
When might Colony stimulating factors increase (CSF)
- Increase in infection
What stimulates platelet production?
- stimulated by thrombopoietin (TPO)
What forms the secondary lymphoid tissue?
- spleen and the lymph nodes
What forms the lymphatic system?
- nodes and vessels
What are lymphatic channels?
- collect fluid and take to main circulation
- passive unidirectional flow
What is the role of lymph nodes?
- fluid percolates through the node for immune sampling
What is the structure of lymph nodes?
- small (up to 2.5cm) oval bodies
- located along the course of lymphatic vessels
What is the sentinel lymph node
- the 1st lymph node to which cancer cells are most likely to spread
How can the sentinel node be examined?
- using dyes or radioactive isotopes
Where are B cells found in the lymph node?
- the follicles
Where are plasma cells found in the lymph node?
- deeper in the medulla
Where are T cells found in the lymph node?
- intrafollicular tissue
Granulomatous lymphadenitis may indicate?
- sarcoidosis
- caseous necrosis = mycobacterial TB until proven otherwise
What is lymphoma?
- malignant tumour derived from cells of the immune system
What is the most common lymphoma?
- Non-hodgkin lymphoma
B cell most common then T cell
Why is it named non-hodgkin lymphoma?
- it doesn’t contain reed-sternberg cells
What is the function of the red pulp of the spleen?
- sinusoids and cords
- act as a filter of blood cells
What is the function of white pulp
- located around arterioles
- compromises of CD4+ T cells
- antigen presenting for immune response
Howell jolly bodies is a sign of what?
- spleen removal
What forms the germinal centre?
- proliferation of centroblasts
