Cells Flashcards
(98 cards)
What is a haematocrit?
A measure of the percentage of total blood volume made up by red blood cells. (Increased in polycythaemia.)
What proportion of blood is cells?
45% cells, 55% plasma.
Function of red blood cells.
Carry oxygen from lungs to tissues, and carbon dioxide from tissues to lungs.
Function of neutrophils.
Granular leukocyte. Phagocytosis and killing bacteria with lysozyme. Part of innate immunity and inflammatory response.
Function of eosinophils.
Granular leukocyte. Kill parasitic worms (helminths), and combat effects of histamine in allergic reaction by phagocytosing antibody-antigen complex.
Function of basophils.
Granular leukocyte. Secrete histamine, heparin, and serotonin to intensify overall inflammatory response.
Function of T lymphocytes.
Agranular leukocytes. Attack invading viruses and cancer cells and transplanted tissue cells.
Function of B lymphocytes.
Agranular leukocytes. Develop into plasma cells which secrete antibodies.
Function of natural killer cells.
Attack infectious microbes and spontaneously arising tumour cells.
Function of platelets.
Subcellular fragments from megakaryocytes. Form a platelet plug to prevent blood loss in haemostasis, and secrete chemicals to stimulate vascular spasm and blood clotting.
Where does haematopoeisis occur before birth?
Yolk sac, then thymus, liver and spleen.
Where does haematopoiesis occur?
Red bone marrow (mostly in axial skeleton but also in pelvic and pectoral girdle, and proximal epiphyses of humerus and femur).
What is red bone marrow?
Highly vascularised connective tissue in the microscopic spaces between the trabecular of spongy bone tissue.
Name the two stem cells the pluripotent stem cells in red bone marrow differentiate into.
Myeloid stem cell (forms proerythroblasts, megakaryoblasts, mast cells, basophil myeloblasts, eosinophil myeloblasts, myeloblasts, monoblasts), and lymphoid stem cell (forms B lymphoblasts, T lymphoblasts, natural killer lymphoblasts).
Name the haematopoeitic growth factors.
Haematopoiesis is regulated by growth factors produced in stroma.
Erythropoietin, EPO (secreted by interstitial fibroblasts in kidney).
Thrombopoietin, TPO - Mpl ligand - also stimulates proliferation of LT-HSCs (secreted by liver).
Cytokines (glycoproteins secreted by red bone marrow cells and leukocytes and macrophages [autocrine and paracrine] that increase proliferation of progenitor cells) e.g interleukins 1 2 3 and 7, colony-stimulating factor (CSF), c-kit ligand (stem cell factor).
Name the blood cells that have similar cells normally found in tissues.
Basophils (mast cells in connective tissue).
Monocytes (mature into dendritic cells and macrophages in the tissue).
State the approximate intravascular lifespan of red blood cells, neutrophils and platelets.
Red blood cells = 120 days (100-200).
Neutrophils = 1 - 2 days (days in spleen and other tissues).
Platelets = 5 - 9 days.
State the components of blood plasma.
Water (solvent, distributes heat).
Plasma proteins (albumins [maintains oncotic pressure for fluid exchange at capillary bed], globulins [immunoglobulins produced by plasma cells], fibrinogen [for blood clotting]).
Electrolytes.
Nutrients (glucose, glycerol, fatty acids, amino acids, vitamins and minerals).
Gases (carbon dioxide, oxygen, nitrogen).
Regulatory molecules (hormones, enzymes, vitamins [cofactors for enzymes]).
Waste products (urea, creatine, creatinine, bilirubin, ammonia [most from protein metabolism]).
What is the name of the glycolipids and glycoproteins (antigens) on the surface of erythrocytes that determine blood type?
Agglutinogens.
The antibodies for these are called agglutinins.
Name two major blood groups.
ABO and Rh.
In the blood group ABO, what blood type is someone whose RBCs display neither antigen A or antigen B?
Type O.
They will have agglutinins for both anti-A and anti-B in their plasma
What is the genetic basis of the ABO blood group?
The ABO gene codes for a glycosyltransferase which catalyses the final step in the production of the agglutinogens. There are three polymorphisms, one which codes for antigen-A, one for antigen-B, and one which codes for an inactive glycosyltransferase which results in blood type O.
What are the consequences of an incompatible blood transfusion?
The recipient’s antibodies will bind to the antigens on the donor RBCs causing AGGLUTINATION.
Also, the complement proteins in the plasma will make the donor RBC’s plasma membranes leaky so haemoglobin pours out into the plasma (haemolysis). The haemoglobin may damage the kidneys by blocking filtration membranes in the glomeruli.
What is agglutination?
Clumping of red blood cells due to an antibody-antigen response in which RBCs become cross-linked to each other.