14 Haemopoesis Flashcards
What is haemopoesis?
Process of cells getting from bone marrow to blood
Haemopoeitic stem cells
In bone marrow
Large bank to fuel cells of blood
Ability to self replicate and differentiate further
Multipotent
Common progenitors
Only have ability to differentiate into lineage bound
Selection of blood cells
Some undergo apoptosis
250 million erythrocytes formed per day, but this is proportion of overall cells produced
RBCs
Life span of 120 days
Degraded by liver/spleen
One RBC contains 1 billion molecules of oxygen
Takes 20 seconds for RBC to circulate body
7 micrometers diameter
RBCs structure
Biconcave shape
No nucleus/minimal organelles
No mitochondria to ensure oxygen not used up
Haemoglobin to increase affinity of oxygen binding
Erythropoiesis
Erythroblasts start with large nucleus and large amounts of DNA
Gradually nucleus shrinks and removed with most RNA
Reticulocytes
Final step before mature erythrocyte
No nucleus
Small amount of RNA to make haemoglobin
Lots of reticulocytes in blood when body recovering from blood loss
Erythropoietin
Glycoproteins produced by kidney to increase levels of RBC
Produced by kidneys in response to tissue hypoxia
Acts to stop apoptosis of erythrocyte progenitors
Made in liver when fetus, taken over by kidney around birth
Granulocytes
Group of WBCs
Have granules in cytoplasm
Mediate inflammatory reactions in body
Release cytokines, interleukins and leukotrienes
3 types: neutrophils, basophils, eosinophils
Neutrophils
First line of defence against bacteria
Multi-lobed nucleus
3 types of granules
Most abundant granulocyte
Function of neutrophils
Granules contain lysozomes, matrix metalloproteinases (MMPs) and gelatinase
Phagocytosis
Signalling and antigen presentation
Neutrophil extracellular traps (NETs) - capture pathogens and kill bacteria
Respiratory burst
Granulocyte-colony stimulating factor (G-CSF)
Secreted by immune cells and endothelial cells
Released in response to inflammation
Act on bone marrow to increase number of neutrophils
Increases speed at which neutrophils mature
Basophils
Release histamine, trigger inflammation Mediate hypersensitivity reactions Bi-lobed nucleus Purple granules Granules contain histamine and heparin (blood thinner)
Eosinophils
Phagocytose pathogens Fight parasitic worms Granules contain antihelminthic proteins and cell component destroying enzymes 2 nuclear lobes Spherical granules
Granulopoiesis
All 3 lineages go through process of:
Nuclear condensation and lobulation
Formation/increased numbers of granules
Monocytes/macrophage
Monocyte in blood, macrophage in tissue First line of defence Phagocytose pathogens Present foreign antigens Largest of mature blood cells Unilobular shaped nucleus
Platelets (thrombocytes)
Stop belting and mediate haemostasis
Biconvex shape
No nucleus
Lots of protein, ribosomes and clotting factors
Special receptors on surface cause platelet aggregation
Thrombopoiesis
Unregulated by thrombopoeitin from liver
Formed from megakaryocyte breaking down
What are the 3 types of lymphopoiesis?
B lymphocyte
T lymphocyte
Natural killer cell
B lymphocytes
Production of antibodies B cell specific to specific antigen Activate T cells Humoral adaptive immunity Maturation occurs in bone marrow
T lymphocytes
Kill virus infected cells, neoplasticism cells and transplanted tissue
Cell-mediated immunity
Activate B cells to make antibodies
Large nucleus, small rim of cytoplasm
Proliferation and activation caused by IL 2
Microscopically indistinguishable from B cells
Migration of T cells
Start in bone marrow or feral liver
Migrate to thymus to mature
Migrate to secondary lymphoid organs
Plasma
92% water
8% protein - albumin, clotting factors, hormones,cytokines, antibodies
Contains ions
