Lecture 21: Blood composition and function Flashcards
Why is blood pressure important?
Ensures
- even and efficient flow through the small capillaries
- low enough to prevent capillary leakage but high enough to avoid coagulation
What are the major components of blood?
Cells Proteins Lipids Electrolytes Vitamins, hormones Complement Glucose
What are the 3 types of cells in the blood
Erythyroid
Myeloid
Lymphoid
What are the 3 layers created when blood is centrifuged?
Red blood cells on the bottom
Buffy coat, comprised of white blood cells and platelets in the middle
Plasma on the top
Require anti-coagulant
What are examples of proteins found in blood?
Albumin - homeostatic function
Haemoglobin - carry oxygen
Fibrinogen - causes blood to clot
Immunoglobulins - antibodies
How are lipids found in the blood?
Lipids are found bound in lipoproteins - HDL, LDL, VLDL
What are electrolytes?
Salts and minerals e.g. Na+ Cl- Ca2+ etc.
What are erythyroids?
Red cells that carry haemoglobin
What are myeloids?
Cells involved in internal innate immunity e.g. phagocytes
What are lymphoids?
Cells involved in adaptive immunity
What is plasma?
The viscous liquid fraction of blood without cells - contains fibrinogen that is removed with coagulation
What is serum?
Less viscous yellow liquid remaining after removal of the clot
What is serum electrophoresis?
Serum proteins exposed to an electric field separates into 5 distinct bands
What is multiple myeloma?
Is a form of leukaemia where a malignant lymphocyte overproduces monoclonal Ig.
Serum electrophoresis is used to diagnose this condition.
What is albumin?
Constitutes 50% of total blood protein
Maintains colloidal osmotic pressure. Binds and transports many small molecules, hormones.
What is fibrinogen?
Constitutes 7% of total blood protein. Activated through the coagulation cascade to form cross-linked fibrin (blood clot)
What is a complement?
Component of blood - 9 proteins that coat bacteria allowing them to be targeted for phagocytosis (process called opsonisation)
What is opsonisation?
Binding to pathogen and coat the bacteria
Deposition of complements on microbes become convertases. Convertases are able to activate more complement that then deposits to coat the surface.
What are coagulation factors?
13 proteins cleaved in an ordered cascade resulting fibrinogen -> fibrin. Failure for this process to occur due to factor VIII deficiency causes haemophilia
What is the function of electrolytes?
Isotonicity and buffering - blood pH is very tightly maintained at 7.4.
What is the name of the stem cell which gives rise to blood cells?
CD34+ Multipotential hematopoietic stem cell (hemocytoblast)
What are the two progenitor cells formed from hemocytoblast?
Common myeloid progenitor and common lymphoid progenitor
What is the application of CD34+ antigens?
The body contains anti-CD34 antibodies that can select and concentrate HSCs from blood prior to a bone marrow transplant in patients that have undergone chemotherapy (killed stem cells) - autologous human stem cell transplants
What are the cells created from the common myeloid progenitor?
Megakaryocyte
Erythrocyte
Mast cell
Myeloblast
What are megakaryoctes?
Cells that produce thrombocytes (platelets)
What are the cells created from the myeloblasts?
myeloid cells - cells involved in the internal innate immune response
Basophils (filled with granules)
Neutrophil (multi-lobed nucleus)
Eosinophil (stain red and divided nucleus)
Monocyte (forms macrophage)
What are the cells created from the common lymphoid progenitor?
Natural killer cell
Small lymphocytes
What are the types of small lymphocytes?
T lymphocyte and B lymphocyte
What do B cells do?
Produce plasma cells that secrete antibodies
What are the three factors that drive haematopoiesis?
GM-CSF, EPO, G-CSF drive production of blood components
What is the GM-CSF?
Granulocyte macrophage colony-stimulating factor
Produced by macrophages, T cells, endothelial cells and fibroblasts
Stimulates production of neutrophils, eosinophils, basophils and monocytes
What is the G-CSF?
Granulocyte colony-stimulating factor
Produced by many different cells
Stimulates production of granulocytes but also acts to mature neutrophils
What is EPO?
Erythropoietin - drives production of RBCs
It is produced mainly by the kidney during adulthood and liver in perinatal
Can be taken as a drug for improved oxygen uptake
How are GM-CSF and G-CSF used following radio-ablation?
These factors are administered to re-populate white cells in leukaemia patients - only small group of white blood cells following transplant
Where does oxygen transport occur?
At the alveoli in the lung - little air sacks that increase surface area for O2 and CO2 to be exchanged between the capillaries and air space.
What is haemoglobin?
Protein found in the blood containing 4 heme groups which contain iron atoms that bind oxygen
What is the binding of O2 to haemoglobin regulated by?
The partial pressure of O2
How does cyanide cause death?
Cyanide binds to cytochrome C in the ETC interrupting oxidative phosphorylation and preventing the heart from beating
What are neutrophils?
Phagocyte which engulfs invading bacteria
Functions as the complements in the blood coat the bacteria by opsonisation
What are the 3 ways of activating complements?
Classical antibody activation
Lectin activation
Alternative activation
How does classical antibody activation work?
An antibody binds to the pathogen causing a cascade to occur and complement to be activated
Which is the most abundant complement component that causes the proteolytic activation cascade?
C3 activated to form C3b which bind to the pathogen
What are convertases?
Deposited complements on pathogens that bind irreversibly via covalent bonds and allow the pathogen to be engulfed by phagocytes
How does oponisation allow neutrophils to seek and engulf bacteria?
Cleavage of C3, C4, and C5 convertases (deposited complements) produce small fragments when cleaved - C3a, C4a, C5a
These fragments act as powerful chemoattractants called anaphylotoxins that attract and activate neutrophils
What are the two pathways for activation of the proteolytic activation cascade which causes coagulation?
Intrinsic - caused by contact with surfaces
Extrinsic - caused by tissue damage
What is the enzyme that is involved in both the intrinsic and extrinsic pathways to coagulation activation?
Factor X forms factor Xa which causes the formation of thrombin from prothrombin
Thrombin then causes fibrinogen to cleave forming fibrin that forms the blood clot
What is thrombin?
Thrombin is the enzyme that cleaves fibrinogen to fibrin which forms cross-links
What do anticoagulants produced by parasites do?
As they rely on blood flow, they produce anti-coagulants that target the thrombin step preventing fibrinogen to form fibrin
What is plasminogen?
An enzyme converted to active plasmin which dissolves the clot - thrombolysis
What is TPA and Streptokinase?
These are plasminogen activators that are used to treat thrombosis - formation of unwanted blood clots.
Plasminogen will form active plasmin which breaks down blood clots.
