Physiology of blood cells and haematological terminology Flashcards
Describe the origin and the life cycle of an erythrocyte:
Begins as pluripotent haematopoietic stem cells in the bone marrow.
Then becomes a multipotent myleiod stem cell –> proerythroblast –> erythroblast –> erythrocyte
Note: blasts have a large nucleus and less cytoplasm.
What two types of stem cells are there and what do they differentiate into?
Pluripotent myleiod stem cells - erythoids, megakaryocytes and granulocytes
Lymphoid stem cells - T cells, B cell and NK cells
Where is erythropoeitin released from and in response to what?
95% the kidneys - juxtatubular interstilitial cells
5% the liver.
Released in response to hypoxia.
Describe a RBC:
lifespan 120 days
No nucleus - has an extensive cytoskeleton which allows it to be flexible and fit through small holes in capillaries.
Destroyed in the spleen by phagocytic cells - the older they get the less flexible so cannot squeeze past the wall of the spleen
Transports oxygen and carbon dioxide
What is anisocytosis?
RBC shows a greater variation in size than is normal.
What is pokiliocytosis?
RBC show more variation in shape than is normal.
What is microcytosis?
Smaller than normal RBC
What is macrocytosis?
Larger than normal RBC - compare their size to that of a lymphocyte
What is hypochromatic RBC?
This is when there is a larger area than normal of central pallor; this should only be 1/3 of the cell. This leads to a flatter cell as there is less haemoglobin.
What is hyperchromatic RBC?
This has no central pallor. This is due to them being thicker than normal or an abnormal shape.
What are the two main types of hyperchromatic cells?
Spherocytes - this is round and has regular outline - result from a loss of cell membrane
Irregularly contracted cells - this will not be a complete circle, smaller than normal cells - usually due to oxidant damage
What is rouleaux?
This is when the RBC stack up like a pile of coins due to alterations in the plasma proteins.
What is agglutinates?
This is when the RBC clump up not in a tidy stack like roulauex due to the antibodies on their surface making them adhere.
What is a howell jolly body?
This has a dot in the corner and this is a remnant of the nuclear material. This shows that there is some splenic failure and the spleen should remove all nuclear material
What is a target cell?
This is a pokiliocyte that has the haemoglobin accumulating in the middle of the cell. It is due to: -Obstructive jaundice failure - liver disease - Haemoglobinopathies - Hyposplenism
What is elliptocytes?
This is an elliptic shaped RBC.
Occur in:
-Hereditary elliptocytosis
-Iron deficiency
What is sickle cell?
this is sickle shaped cells due to the polymerisation of a large concentration of the haemoglobin s chains.
What is polychromasia?
This is when the blue -methyelene blue dye is retained . This shows that this is a young RBC - a reticulocyte.
What are the different types of pokiliocytosis?
Spherocytes irregularly contracted cells sickle cells target cells ellipocytes fragments
What are fragments?
They don’t look like full cells
A.K.A schistocytes
Cells are defective or due to abnormal stress.
What is the formation of white blood cells?
myeloblast –> granulocytes –> specialised cells
Needs interleukin and cytokines.
Large nucleus; little cytoplasm
Describe neutrophils:
7-10 hours in circulation
Defence against infection
Phagocytosis and kills microorganisms.
Multi-lobed nuclei
Describe eosinophils:
Less time in circulation than neutrophils
Defence against parasitic infections
Two lobes in the nucleus
Describe basophils:
Involved in allergic responses
Dark blue dots - do not see nucleus
Describe monocytes:
Several days in the circulation
Large cells with a kidney bean shaped nucleus
Migrate to tissues where they become macrophages
Also store and release iron.
Describe platelets:
Platelets are derived from megakaryocytes.
Survive 10 days in the circulation
Primary role in homeostasis.
Describe lymphocytes:
Recirculate in the lymph and back to the blood stream.
Involved in defence and give rise to T, B and NK cells.
What does cytosis/philia show?
Too many of a thing
What does penia show?
Too few of a thing
Which WBC’s shape is of interest?
Lymphocytes as these are usually the same.
They usually have a large nucleus and a small cytoplasm.
What is left shift?
This is when there is an increase in non-segmented neutrophils or neutrophil precursors in the blood.
What is toxic granulation?
Heavy granulation of neutrophils due to infection, inflammation and tissue necrosis.
Also a feature of normal pregnancy/
What is a hyper segmented neutrophil?
Increase in the average number of neutrophil lobes or segments.
Usually due to a lack of B12 or folic acid
