Week 9 - Haematology Flashcards
what is the structure of erythrocytes?
biconcave discs = maximises surface area
anuclear
all intracellular organelles are lost in erythropoiesis
what is the function of erythrocytes?
- Delivers oxygen from the lungs to the tissues all through the body
- Facilitates carbon dioxide transport
- Acts as a buffer and regulates hydrogen ion concentration
- Contributes to blood viscosity
Carries blood group antigens and Rh factor
what types of haemoglobin are found in adults?
HbA
HbA2
what is erythropoiesis?
process of producing RBCs
from eryhtropoietic stem cell to mature RBC
stimulated by decreased O2 in circulation which is detected by kidney which produce erythropoeitin
what is a reticulocyte?
premature RBC containing ribosomal RNA
at what point do RBCs extrude their nucleus?
when they’re normoblasts
what is the function of erythropoietin?
regulates erythropoiesis
made in liver and kidneys
where are most RBCs destroyed?
liver, spleen and lymph nodes
by macrophages
what do RBCs break up into?
haem -> bilirubin
globin -> amino acids and iron
What is the main function of the spleen?
Filters the blood
Removes old/damaged RBCs
What cells make platelets?
Megakaryocytes
What is the main function of platelets?
Platelet aggregation
Plugs gap where blood clots need to form
What is the structure of a platelet?
Anuclear
They are fragments of cytoplasm from megakaryocytes
Have a dense membrane and tubular network
Contain alpha bodies and dense granules
Biconvex
What is found in the alpha granules in platelets?
Proteins
Factor XIII, platelet activating factor, PDGF, vWF, fibrinogen + platelet factor 4
What is found in the dense bodies in platelets?
Non proteins
ADP + Ca2+ (needed for contraction and bind to vitamin K dependent factors)
What is thrombocytopenia?
Not enough platelets
What is thrombocytosis?
Too many platelets
How are platelets activated? And how does aggregation occur?
- Platelets get exposed to endothelial damage
○ Exposed to vWF, collagen etc leads to activation- Intracellular signalling causes release of granules and generation of thromboxane
- Secondary mediators reinforce the platelets activation and activate further platelets
- Thrombin generation causes further activation of platelets
- Intracellular signalling leads to integrin activation
- Active integrin binds fibrinogen and causes platelet aggregation
- This forms the platelet aggregate primary plug
- Thrombin converts fibrinogen in the platelet aggregate to cross linked fibrin
○ This forms the secondary haemostatic plug = thrombus
What is the structure of a neutrophil?
They have a characterise multilobed nucleus, with 3-5 lobes joined by slender genetic material.
What is the function of a neutrophil?
First cell when body is exposed to infection and mature neutrophils (polymorphonuclear neutrophils) ingest microorganisms, help defence of body as they are actively phagocytic.
What is the structure of eosinophils?
Larger cytoplasmic granules, tend not to have more than 3 lobes.
What is the function of eosinophils?
Provide protection against parasite infections.
Involved in the allergic responses.
What is the structure of a basophil?
Usually consist of 2 nuclear segments, cytoplasmic granules contain heparin and histamine.
What are found in the granules in basophils?
Heparin
Histamine
What is the function of basophils?
They mature in tissues to form mast cells.
Both play a role in hypersensitivity – release inflammatory molecules such as histamine to defend body from allergens, pathogens and parasites.
Basophils also release enzymes to improve blood flow and prevent blood clots.
What is the structure of monocytes?
Spherical cell with prominent surface ruffles and blebs
What is the function of monocytes?
Made in bone marrow and travels through the blood to tissues in the body where it differentiates to becomes a macrophage or a dendritic cell when body is exposed to a foreign body.
Macrophages are innate immune cells which are involved in the detection, phagocytosis and destruction of bacteria and other harmful organism.
What are the 3 types of lymphocytes?
T cells
B cells
NK cells
What is the structure of natural killer cells?
NK cells tend to be larger cells with relatively large granules scattered in their cytoplasm.
What is the function of T cells?
responsible for cell-mediated cytotoxic reactions and for delayed hypersensitivity responses. T lymphocytes also produce the cytokines that regulate immune responses and provide helper activity for B cells