Physiology of blood cells Flashcards
what do pluripotent haematopoietic stem cells give ruse to?
- lymphoid stem cells
- myeloid stem cells
what does the multipotent myeloid stem cell give rise to?
- granulocyte: monocyte
- erythroid
- megakaryocyte
what do lymphoid stem cells give rise to?
- T cell
- B cell
- NK cells
what ability do stem cells have?
- ability to self renew whilst also producing mature progeny
- divides into itself and a mature cell
describe the steps to erythroid maturation
- multipotent myeloid stem cell
- proerythroblast
- erythroblast
- erythrocytes
where is erythropoiesis synthesized? what is it released in response to?
90% from juxta tubular interstitial cells of kidneys
10% from hepactocytes and interstitial cells of liver
released in response to hypoxia
how are erythrocytes destroyed?
- survive 120 days in blood stream
- destroyed by phagocytes in spleen
describe the maturation of white cells. what is required?
multipotent myeloid stem cell –> myelobalst –> granulocytes/ monocytes
cytokines/ILs needed
what is the life span and function of neutrophils
survive 7-10hrs in circulation
then migrate to tissues
defence against infection
what is the fucnction of eosinophils? how long in circulation?
- less time in circulation than neutrophils
- defence against parasitic infection
what are basophils involved in?
allergic response
what are the functions of monocytes?
- spend several days in circulation
- phagocytose bacteria, fungi, dead tissue
- migrate to tissue –> become macrophages
- store and release iron
describe how platelets are formed
multipotent haematopoietic stem cell –> megakaryocyte –> platelet
what do platelets do and how long do they spend in circulation?
- survive 10 days in circulation
- role in primary haemostasis
- contribute phospholipid to promote blood coagulation
what do lymphocytes do?
- recirculate to lymph nodes and other tissues and then back to blood stream
- variable life spans
define anisocytosis
variation in size
define poikilocytosis
variation in shape
what does microcytosis mean?
smaller than normal
define macrocytosis
- larger than normal
- round/ oval/ polychromatic macrocytes
what are the 3 broad categories for anaemia?
- microcytic: red cells that are smaller than normal
- normocytic: red cells of normal size
- macrocytic: red cells that are larger than normal
what is hypochromia?
- RBCs that have large central pallor
- less Hb in cell –> flatter cell
- also often microcytic
what is the normal paleness of RBCs?
normal RBCs have 1/3 diameter than is pale
what is hyperchromia?
- cells lack central pallor
- cells are thicker than normal
- have abnormal shape
what are 2 important types of hyperchromic cells?
- spherocytes
- irregularly contracted cells
describe spherocytes. what does it result from?
- spherical in shape –> lack central pallor
- results from loss of cell membrane without equivalent loss of cytoplasm
- cell is forced to round up
- e.g. hereditary spherocytes
describe irregularly contracted cells. what causes it?
- irregular in outline
- smaller than normal cells
- have lost central pallor
- result of oxidant damage to cell membrane and Hb
what is polychromasia?
- inc. blue tinge to cytoplasm of a red cell
- indicated cell is younger and much larger
name all the different types of poikilocytes
- spherocytes
- irregularly contracted cells
- sickle cells
- target cells
- elliptocytes
- fragments/shistocytes
what are target cells?
cells with accumulation of Hb in centre of area of central pallor
occurs in obstructive jaundice, liver disease, hyposplenism
what are elliptocytes?
- elliptical in shape
- hereditary elliptocytosis and iron def
what are sickle cells?
- results from polymerisation of Hb S chains when present at high enough conc
what are fragments/shistocytes?
- small pieces of red cells indicating a cell has fragmened
- can be due to abnormal stress on red cell
- or if cell is intrinsically abnormal
what is a rouleaux?
- stack of red cells
- result from alteration in plasma proteins
what are agglutinated?
- irregular clumps of RBC
- result of antibodies on surface of cells
what is a Howell- jolly body?
- nuclear remnant in red cell
- cause = lack of splenic fucntion
define leucocytosis
too many white cells
define leucopenia
too few white cells
define neutrophilia
too many neutrophils
define neutropenia
too few neutrophils
define lymphocytosis
too many lymphocytes
define eosinophilia
too many eosinophils
what is left shift?
- inc. in non-segmented neutrophils
- neutrophil precursors in blood
- left –> right is normal
- right –> left is left shift
what is toxic granulation?
- heavy granulation of neutrophils
- due to infection, inflammation, tissue necrosis
- normal in pregnancy
what are hypersegmented neutrophils?
- inc. in average number of neutrophil lobes/segments
- due to lack of Vit B12/folic acid
