1. Physiology of blood cells and haematological terminology Flashcards
(38 cards)
What do multipotent haematopoeitic stem cells give rise to (include production of erythrocytes)?
• Lymphoid stem cells (then T, B, NK)
• Myeloid stem cells (then erythroids, granulocytes and megakaryotes)
=> proerythroblast => erythroblasts => erythrocytes
What are essential stem cell characteristics?
- Ability to self-renew and produce mature progeny
* Ability to divide into 2 cells with different characteristics
How does the cytoplasm change as erythrocytes differentiate?
Dark blue to more pink
What does erythropoeisis require and how is this obtained?
- Erythropoeitin
- Synthesised in juxtatubular interstitial cells in the kidney in response to hypoxia (90%)
- Partly mader in liver hepatocyte and interstitial cells (10%)
How long does an erythrocyte survive in the blood stream and how is it ultimately destroyed?
- About 120 days
* Destroyed by phagocytic cells of the spleen
How do multipotent haematopoeitic stem cells give rise to white blood cells
=> myeloblasts
=> granulocytes and monocytes
• Cytokines needed including, G-CSF, M-CSF, GM-CSF and various interleukins
What do myeloblasts look like?
- Large nucleus, little cytoplasm
* Similar to proerythroblasts
How long do neutrophils survive in circulation?
7-10 hours before migrating into tissues
What is the process of neutrophils migrating into tissues called?
Diapedesis
Outline the function of eosinophils and basophils
- Eosinophils - defence against parasitic infection (2 lobes, less time in circulation)
- Basophils - allergic responses (so many dark blue dots, hard to see nucleus)
How do haematopoeitic stem cells differentiate into platelets?
=> megakaryocytes
=> platelets
How long do platelets survive in circulation?
10 days
How long do lymphocytes survive in the blood stream?
Very variable, may be very long lived
What is anisocytosis?
RBCs show more variation in size than normal
What is poikilocytosis?
RBCs show more variation in shape than normal
What is micro- and macrocytosis?
- Micro - RBCs are smaller than normal
* Macro - RBCs are larger than normal
What can you use as a reference to determine a micro or macrocyte?
Lymphocytes
What does microcytic describe?
RBCs that are smaller than normal or anaemia with small RBCs
What is hypochromia?
- Normal RBCs have 1/3 of the diameter that is pale
- Hypochromia - cells have a larger area of central pallor than normal
- Due to lower haemoglobin and flatter cell
- Usually goes together with microcytosis
What is hyperchromia?
- Cells lack central pallor (lack pale appearance)
* Could be because thicker or abnormal shape e.g. spherocytes + irregularly contracted cells
What are spherocytes?
- Cells approx. spherical in shape and lack central pallor
- Result from loss of cell membrane without loss of equivalent amount of cytoplasm
- Occurs in hereditary spherocytosis
What are irregularly contracted cells?
- Irregular in outline
- Smaller than normal cells
- Lost central pallor
- Usually result from oxidant to the membrane and haemoglobin
What is polychromasia and in what cells does this occur?
- An increased blue tinge to the cytoplasm of a RBC
- Indicates that the cells are young
- Reticulocytes are RBCs that are slightly younger than mature cells - stained with methylene blue - binds to ribosomes
What does an reticulocytosis in an anaemic patient show?
Bone marrow is capable of making new cells
