December Exam Review Notes 6

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Department
Anatomy and Cell Biology
Course
Anatomy and Cell Biology 3309
Professor
Kem Rogers
Semester
Fall

Description
 Deep blue cytoplasm (because of ribosomes)  Nucleoli have disappeared  Chromatin has started to condense o Polychromatophilic erythroblast  Pink (eosinophilic) patches in cytoplasm due to collection of haemoglobin  Still has basophilic staining because of ribosomes  This is the last stage at which division occurs o Normoblast  Pyknotic nucleus (chromatin is fully condensed)  Pink cytoplasm due to haemoglobin  Still has a FEW organelles  Does NOT divide!! (because of condensed nucleus) o Reticulocyte  Forms upon the extrusion of the nucleus  Some ribosomes are present, therefore, can have a slight blue tinge o Erythrocyte  Mature RBC  Lasts in bloodstream for approx. 120 days  Erythropoietin (EPO) stimulates erythrocyte production near the committed stem cell stage o It is produced by the kidneys in response to low O2 levels o An increase in the number of RBCs in the bloodstream means more O2 can be carried  Blood doping refers to the process where you take out your own blood/someone else’s blood and store it o You then add it back before competition to increase RBC count to carry more O2  Anemias o Microcytic (small cell)  Low iron results in small, pale cells (due to lack of haemoglobin)  These cells are termed hypochromic, because they are below the normal level of colour o Megaloblastic anemia  There is low B12, folate, or intrinsic factor (which is used in binding B12)  It results in slowed proliferation and large, fragile cells  These cells still have a lack of haemoglobin  Megakaryocytes have a polyploidy, continuous nucleus o They are always found adjacent to sinusoids, which are capillaries with large lumens o They dump platelets into sinusoids  There are 2 types of bone marrow: o Red (blood-producing)  This still has adipocytes o Yellow/white (adipose tissue)  Only mature cells are released from bone marrow and into the bloodstream  In a light micrograph, cresyl violet can be used to distinguish between reticulocytes and erythrocytes o This is because it labels fragments of organelles left behind after enucleation  The presence of reticulocytes in blood means something is wrong o For example, in blood doping with EPO, too many cells can be produced and released prematurely as reticulocytes o In massive haemorrhaging, we can find reticulocytes in blood because they CAN carry oxygen  Recall that primary granules are azurophilic granules o These are found in all granulocytes o They are lysosomes containing myeloperoxidase (i.e. modified lysosomes)  Specific granules are specific to the type of granulocyte o These are secondary granules o They are NOT derived from primary granules o Neutrophils  These are bacteriocidal  Eg. Collagenase, phospholipase  These are involved in bacterial and fungal responses o Eosinophils  Antiparasitic/antihalmetic  Major basic protein, peroxidise, histaminases o Basophils  IgE sensitivity and anaphylaxis (i.e. allergic response)  Also contain chemicals that attract eosinophils, which also help modulate the allergic response  Heparin, histamine, heparin sulphate, leukotrienes  These leukocytes circulate in the blood, but then enter tissue to do their jobs  Granulocytic lineage o Myeloblast  3-5 prominent nucleoli (ribosome synthesis)  Basophilic cytoplasm  This is the first recognizable stage in granulopoiesis o Promyelocyte  1 or 2 nucleoli  Primary azurophilic granules (bright pink/magenta)  When these cells divide, they divide up their primary granules too  Since the proteins are packaged into granules, we can see negative golgi  We still don’t know which of the granulocytes will be formed o Myelocyte  Specific (secondary) granules appear  Nucleoli disappear because granules have already been made; no more ribosomes needed  The nucleus may have a SLIGHT indentation o Metamyelocyte  Definitely indented nucleus  From here, mature eosinophils and basophils form o Band neutrophil (ONLY FOR NEUTROPHIL)  Elongated, even, C-shaped nucleus  Since neutrophils have the greatest representation among the granulocytes in blood, we expect to see a lot of these in a smear  Megakaryocytes are huge polyploidy cells that underwent many nuclear divisions (upto 7) o There are only nuclear division, NOT cytoplasmic o They have pseudopods (projections) that project into sinuses (capillary with large lumen) o Platelets break off from these pseudopods  In platelets, we can see demarcation channels o These originally arise in pseudopods, where they are discontinuous perforations o When they join, that part of the cell breaks off o However, in platelets, we see residual demarcation channels that did not participate in the break  There are 2 divisions of the immune system: o Innate immune system  This includes the surface epithelium and protective mucus with bacteriocidal enzymes o Adaptive immune system  This involves different cells that become activated for an immune response (i.e. recognizing foreign antigens)  Lymph nodes filter lymph (i.e. tissue fluid)  Lymphatic vessels drain all tissue and return lymph to the circulatory system  There are 3 types of lymphocytes o T-cells  Cell-mediated immunity o Natural killer cells  Cell-mediated immunity o B-cells  Humoral immunity  In the lymphatic system, there are various supporting cells: o Reticular cells o Macrophages  These have an important role in engulfing foreign particles and presenting the antigen o Follicular dendritic cells o Langerhans’ cells (skin) o Epithelioreticular cells (thymus)  There are 2 primary lymphatic organs: o Bone marrow and thymus o These are the places where immature lymphocytes become “educated” (immunocompetent) and learn to identify foreign antigens (proteins)  Secondary lymphatic organs include: o Diffuse lymphatic tissue o Lymphatic nodules and nodes o Spleen  In the secondary lymphatic organs, immune cells are ALREADY immunocompetent o Instead, they are activated here and undergo subsequent expansion/proliferation  NK cells o These cells respond to various signalling proteins, which result in activation o Once activated, NK cells can release proteins  Perforins = these punch holes in cell membranes  Fragmentins = these disrupt DNA  T cells o There are various classes of T cells o Macrophages present antigens after engulfing pathogenic cells  This leads to the activation of a corresponding cytotoxic T cell, which proliferates o Activated cytotoxic T cells secrete perforins and fragmentins, which attack and kill target cells  The abovementioned cells are part of the body’s cell-mediated immunity  B cells are part of a cell’s humoral immunity o They produce antibodies o They become activated with help from helper T cells and other signals  This leads to expansion/proliferation o A mature B cell is known as a plasma cell, which can produce antibodies  Plasma cells have very basophilic cytoplasm  This is because they are full of ribosomes synthesizing proteins (Abs)  Therefore, we would also see negative golgi o Activated B cells produce memory cells, which are long-lived and remember the foreign antigen  Memory cells have varying lifespans  T and B cells come from the primary lymphatic organs: o Stem cells for B ce
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