Blood Cells & Haemopoeisis Flashcards
Describe the function of neutrophils
Migrate out of circulation to site of infection (chemotaxis), phagocytosis. Multi-lobed.
Outline the process of haemopoiesis
Proliferation - two cells produced; clone and a cell that differentiates. Haemopoietic progenitor will differentiate into either myeloid blast (RBC, WBC or platelets) or lymphoid blast (immunoresponse cells).
What stimulates neutrophils?
Cytokines (e.g. G-CSF) increase neutrophil prodcution, increase chemotaxis and therefore increase phagocytosis
Describe the action of eosinophils
Capable of phagocytosis. Release cytotoxic particles to damage larger particles. Used in allergic/atopic responses
Describe the appearance of eosinophils
Bi-lobed nucleus, orange colour due to granules (arginine)
Describe the action of basophils
Mediate acute inflammatory responses - release histamine, heparin and hyaluronate
Describe the appearance of basophils
Bi- or tri-lobed nuclei, dark purple colour
Describe the action of B lymphocytes
Used for humoural immunity - produce plasma cells which produce antibodies. Stimulated by antigens to transform into plasma cells.
Describe the action of T lymphocytes
T helper - express CD4 receptors on surface, can be killer cells, permit transformation of B cells to plasma cells
Describe the appearance of lymphocytes
Small, round nucleus. Pale blue in colour
Describe the action of monocytes
Move out of circulation to become macrophages, capable of phagocytosis and interact with T cells. Diapedesis to tissues.
Describe the appearance of a monocyte
Kidney shaped nucleus
Outline the life cycle of a red blood cell
Bone marrow - peripheral red blood cell - removal by the reticulo-endothelial system.
What are the functions of red blood cells?
Deliver O2 to tissues, carry Hb, osmotic equilibrium, generate ATP anaerobically
What is the structure of red blood cells?
Biconcave discs, have four globin chains, each molecule carries a haem
What are the functions of reticular cells?
Direct T and B lymphocytes to specific regions with the lymphatic tissues
What is the structure of reticular cells?
Synthesise reticular fibres and surround them with cytoplasm
What is the reticuloendothelial system?
A part of the immune system containing phagocytic cells. They identify and mount an appropriate immune response to foreign antigens. Main organs - liver, spleen and lymphatic nodes
Which cells are included in the reticuloendothelial system?
Monocytes, macrophages, kupffer cells, tissue histiocytes, microglial cells in the central nervous system
How long do red blood cells last in circulation?
120 days
How long do platelets remain in circulation?
10 days
How long do neutrophils last in circulation?
2-4 days
How long do lymphocytes last in circulation?
1 day - years
Outline two pathways for metabolism in a red blood cell
By the Embden Meyerhof pathway - glucose is metabolised to lactate resulting in ATP generation. Hexose monophosphate pathway - glucose-6-phosphate metabolised, NADPH produced
What are the functions of platelets?
Used in the blood clotting cascade, adhere to cell walls and aggregate
Describe the structure of platelets
Complex surface membrane, produced in megakaryoctes in bone marrow, cytoplasm contains alpha and dense granules, alpha contains fibrinogen and von Willebrands Factor, dense contains Ca2+ and ADP
Describe RBC destruction and catabolism
Bilirubin from haem goes to liver which then goes to the spleen where it is converted to bile. It moves to the large intestine where its converted to urobilinogen and goes to kidney to be excreted. Cn also be converted to stercobilin and excreted in the faeces
