Physiology of blood cells and haematological terminology Flashcards
What are all blood cells ultimately derived from? What two lineages can this give rise to?
Multipotent haemopoietic stem cells (in bone marrow)
=> lymphoid stem cells and myeloid stem cells
What cells are derived from the multipotent myeloid precursor?
Megakaryocytes (and thence platelets)
Granulocyte-Monocyte
Erythroid precursors (proerythroblast => early, middle and late erythroblasts => erythrocytes)
What cells are derived from the multipotent lymphoid precursor?
T cell
B cell
NK cell
How are stem cells able to self renew and produce mature progeny?
Able to divide into two cells with different characteristics; another stem cell + a cell capable of differentiating to mature progeny
Which cells produce erythropoietin? What can trigger the production of erythropoietin? What effect does it have?
- 90% from kidney Juxtatubular Interstitial Cells
- 10% from liver Hepatocytes and Interstitial Cells
- Triggered by hypoxia, anaemia
- Causes increased erythropoiesis in bone marrow
What is the approximate life span of a red blood cell in the blood stream?
120 days
How and why do old red blood cells get destroyed in the spleen
As the cells get older, they becomes less flexible and less able to pass through the capillaries into the sinuses in the spleen
This means that they are more likely to be retained in the spleen and phagocytosed
How does the colour of red cells change as they mature?
When they are immature they are more blue/purple
As they mature they become pinker
Briefly state the cell lineage from multipotent haemopoietic stem cells to granulocytes and monocytes. What molecules are needed to mediate this process?
Multipotent haemopoietic stem => myeloblast + monoblast
Myeloblast => granulocytes (neutrophils, eosinophils, basophils)
Monoblast => monocytes
Cytokines such as G-CSF, M-CSF, GM-CSF and various interleukins are needed
G-CSF = granulocyte colony-stimulating factor; GM-CSF = granulocyte-macrophage colony-stimulating factor M-CSF = macrophage colony-stimulating factor
The neutrophil granulocyte survives for how long in the circulation before migrating to tissues?
7–10 hours
Recall the different stages involved in neutrophil function
Adhesion and margination Rolling Diapedesis Migration (chemotaxis) Phagocytosis
Compare eosinophils and neutrophils in terms of their appearance and life span in circulation
- Eosinophils spends less time in the circulation than do neutrophils
- Eosinophils: bi-lobed nucleus;
Neutrophils: tri-lobed nucleus
State the main role of eosinophils
Defence against parasitic infection
State the main role of basophils
Involved in allergic responses
Describe the appearance of basophils
They have lots of dark blue/purple dots in the cytoplasm (granules)
Describe the appearance of monocytes.
Large cell with a kidney bean shaped nucleus
How long do monocytes spend in the circulation, and what do they develop into when they migrate into tissues?
Several days
Macrophages and other specialised cells that have a phagocytic and scavenging function
Other than phagocytosis, what is another role of macrophages?
Store and release iron
How long do platelets survive for in the circulation?
About 10 days
Define Anisocytosis and Poikilocytosis
Anisocytosis = red cells show more variation in SIZE than is normal
Poikilocytosis = red cells show more variation in SHAPE than is normal
Define Microcytosis and Macrocytosis
Microcytosis = red cells are smaller than normal
Macrocytosis = red cells are larger than normal
Macrocytes can be of three specific types. Name them.
Round macrocytes
Oval macrocytes
Polychromatic macrocytes
Recall the three types of anaemia
Microcytic = anaemia with small red cells Normocytic = anaemia with normal sized red cells Macrocytic = anaemia with large red cells
What can be used as a reference in a blood film to determine whether the red blood cells are microcytic or macrocytic?
Lymphocytes are generally all the same size
