Haemopoiesis Flashcards
What is the lifespan of each of a) red cells, b) platelets, c) neutrophils?
Red cells = 120 days / platelets = 7-10 days / neutrophils = 7-8 hours
What are the 3 main types of white blood cell?
Granulocytes, monocytes and lymphocytes
What is the function of a) B cells, b) T cells, c) NK cells?
B cells = humoral immunity / T cells = cell mediated immunity / NK cells = anti-viral/tumour
If production of blood cells in the bone marrow was to be switched off, in what order would certain cells stop being produced?
Neutrophils first, then platelets and then red blood cells
What change occurs in neutrophils as they become more mature?
There is more segmentation of the nucleus
What does it mean if a cell type ends in -blast? In adults, where would these cell be found?
Nucleated precursor cell / In the bone marrow
What type of cell is a platelet precursor and is polypoid?
Megakaryocyte
What are myelocytes?
Nucleated precursors between neutrophils and blasts
All blood cell precursors begin as what?
Haemopoietic stem cells
Haemopoietic stem cells divide into what?
Two daughter cells which are dissimilar - one is exactly the same as the parent cell (self renewal) and one is a progenitor cell
What is meant be proliferation in terms of haemopoiesis?
An increase in cell number
What is meant by differentiation in haemopoiesis?
Descendants commit to one or more lineages
What is meant by maturation in haemopoiesis?
Descendants acquire functional properties and may stop proliferating
Where do haemopoietic stem cells originate embryonically?
The mesoderm
What is the first site of haemopoiesis in an embryo? Production where also starts at 6 weeks? Production where also starts at week 16?
Yolk sac / liver / bone marrow
Where do arterioles in the bone marrow drain into?
Venous sinuses which open into larger central sinuses
Describe venous sinuses in comparison to capillaries?
They are larger and have a discontinuous basement menmbrane
Venous sinuses in the bone marrow are surrounded by what?
Adventitial cells
What is the difference between red and yellow bone marrow? Which increases as we get older?
Red marrow is haemopoietically active, yellow marrow is fatty and inactive. As we get older, yellow marrow increases
Describe what is meant by the myeloid: erythroid ratio?
The relationship of neutrophils and precursors to the proportion of nucleated red cell precursors
What is the normal range of the myeloid: erythroid ratio?
1.5: 1 - 3.3.: 1
What are some examples of when the myeloid: erythroid ratio may switch (i.e. more erythrocytes)?
Anaemia or haemolysis
How do blood cells leave the bone marrow?
They pass through fenestrations (gaps) in the endothelium
What happens to the venous sinuses in the bone marrow when there is release of red cells? What regulates this?
They dilate / adventitial cells
