Lecture 16: Blood And Haemopoiesis Flashcards
What is the definition of haemopoiesis?
Production of blood cells and platelets in the bone marrow
What is the process of haemopoiesis?
Stem cells in the bone marrow differentiate into different blood cells
What is a hemocytoblast?
Multi potential hematopoietic stem cell
What is the function of a hemocytoblast?
They can self replicate and differentiate further
What are the 2 common progenitors that arise from hemocytoblasts?
Common myeloid progenitor and common lymphoid progenitor
What are erythrocytes?
Red blood cells
What are 4 key features of erythrocytes?
- Bison cave shape to increase surface area for diffusion of gases
- No nucleus to maximize oxygen holding capabilities
- No mitochondria to ensure oxygen is not used up by erythrocytes
- Haemoglobin to increase affinity of oxygen binding
How does erythropoiesis work?
Erythroblasts starts off with large nucleus and large amounts of RNA but nucleus gradually shrinks and is removed along with most RNA, becomes reticulocyte and then becomes erythrocytes
What are reticulocytes?
Final step before becoming a mature erythrocyte, once nucleus has been removed. Still has some RNA to make haemoglobin, which will disappear in 1-2 days
High amount of them can present in the blood when body is recovering from blood loss
How does the body stimulate more RBC production?
Kidney senses tissue hypoxia (low O2) and increases secretion of erythropoietin
What is erythropoietin?
Glycoproteins produced by kidney to increase levels of RBC, acts to stop apoptosis of erythrocytes progenitors
What are granulocytes?
Sub group of white blood cells, they have granules in their cytoplasm
What are the functions of granulocytes?
Mediate inflammatory reactions
What are the 3 types of granulocytes?
Neutrophils, basophils, eosinophils
What are neutrophils?
First responder and first line of defense against bacteria
What are 3 key features of neutrophils?
- Multi lobular nucleus
- 3 types of granules
- most abundant granulocyte
What are the 3 types of granules neutrophils contain?
Lysosomes
Matrix metalloproteinases (MMPs)
Gelatinase
What are 4 functions of neutrophils?
- Phagocytosis
- Signalling and antigen presentation
- Neutrophil extracellular traps
- Respiratory burst
What is the function of granulocyte-colony stimulating factor?
Acts on bone marrow to increase number of circulating neutrophils and increases the speed of neutrophils maturing in response to inflammation
What are the functions of basophils?
Release histamine to trigger inflammation
What are 2 key features of basophils?
Bilobed nucleus and purple granules
What are the 2 substances that the granules in basophils contain?
Histamine and heparin
What is the function of eosinophils?
Phagocytosis pathogens
What are the 2 types of substances that granules of eosinophils contain?
Antihelminthic proteins
Cell component destroying enzymes
What are the 2 key features of eosinophils?
2 nuclear lines and eosinophilia granules
What are the 2 steps of granulopoiesis?
- Nuclear condensation and lobular ion
2. Formation of granules
What are the 2 kinds of agranulocytes?
Monocytes in blood and macrophage in tissue
What are the 2 functions of monocytes and macrophage?
- Phagocytose pathogens, cell debris and senescent cells
2. Present foreign antigens to lymphocytes
What is the key feature of monocytes and macrophages?
Unilobular horseshoe shaped nucleus
What is thrombopoiesis?
Production of platelets from megakaryocyte breaking down
What is thrombooietin?
Substance that increases level of production of platelets
What are the 2 functions of platelets or thrombocytes?
Stop bleeding and mediate haemostasis
What are the 5 key features of platelets?
- Smallest
- Biconvex shale
- No nucleus
- Contain a lot of protein and clotting factors
- Special receptors on surface that cause platelet aggregation
What is lymphopoiesis?
Formation of lymphocytes
What are the 3 types of lymphocytes?
B lymphocyte
T lymphocyte
Natural killer cell
What are the 2 functions of B lymphocytes?
Produce antibodies, activate T cells
Where is B lymphocytes produced and matured?
Maturation occurs in bone marrow and then in intestine, spleen and lymph nodes
What are the 2 functions of T lymphocytes?
Kill virus-infected cells, neoplasticism cells and transplanted tissue
Activate B cells using IL4
What is 1 key structural feature of t lymphocytes?
Large nucleus with small ring of cytoplasm
What is the proliferation and activation of t lymphocytes caused by?
IL 2
Where do T cells mature?
Start off in bone marrow and then migrate to thymus to mature, then migrate to secondary lymphoid organs where they will wait till activation
What is plasma?
Supporting medium for all circulating blood cells
What are 3 examples of plasma proteins?
Albumin, clotting factors, hormones
