| Talk about Blood tissue. | Specialized mesenchymal CT that includes free cells (formed elements) and plasma (ECM liquid).
Contained in network of vessels outside of which it coagulates (clots). |
| What are the roles played by blood tisuue? | Ensuring the consistency of inner environment (body temperature, pH, water balance) and transmits to all tissues O2 and nutrients needed, it also evacuates CO2 and wastes. Transports hormones allows defenses of the body to quickly reach their destined organ, needed for blood clotting during bleeding. Represents 8% of body weight. |
| Talk about plasma. | Aqueous solution corresponds to the ECM of the blood tissue, and represents 55% of blood volume. Composed from:
91.5% water
7% plasma proteins (albumins 55%, globulins 38%, fibrinogen 7%, they confer to blood its viscosity and allow maintenance of osmotic balance and slightly alkaline medium.)
1.5% other solutes (organic material (triglycerides, cholesterol, glucose, urea...) minerals and electrolytes (Cl, Na, K...) dissolved gases.) |
| Talk about formed elements. | 45% of blood volume, heterogenous morphologically and physiologically, Real cells (leukocytes) or cells lacking nucleus or organelles (erythrocytes) or cell fragments (thrombocytes)
RBC and platelets do not leave the blood vessels in normal conditions and exert their functions in blood circulation, whereas leukocytes cross through capillary walls and are found in tissues where they exert their functions. |
| What is a serum? | Contains all plasma elements except those involved in coagulations (fibrin) |
| Describe a normal hemogramme. | Blood count ( RBC 4,500,000- 5,500,000/ mm cube blood- Platelets 150,000- 400,000- WBC 4000- 8000)
Blood formula (leukocyte count) (Neutrophil granulocytes 50- 70% / Eosinophil granulocytes 1-3%/ Basophil granulocyte 0-1% / Lymphocyte 25-40% / monocyte 2-10%) |
| Talk about RBC | AKA erythrocytes, most abundant formed elements, highly differentiated, biconcave disc shaped, flattened in the center, deformable with diameter 6-8 micromm, anucleated and do not posses any cytoplasmic organelles nor do they reproduce or have metabolic activity , cytoplasm consists of mainly hemoglobin, water, also has a cytoskeleton, ADP, enzymes ions and glucose (anaerobic glycolysis) Lifespan is 100-120 days eliminated by hemolysis by macrophages of the liver and spleen |
| Talk about the hemoglobin of RBC. | 33% of total cell mass, gives blood its red color and fixes O2 (oxyhemoglobin) and CO2 (carbaminohemoglobin). |
| Talk about the cytoskeleton of the RBC | closely related to the plasma membrane, maintains the characteristic shape of the cell and allows deformability |
| Talk about glycoproteins of RBC. | AKA agglutinogens, responsible for determination of the BG found in RBC plasma membrane. |
| Talk about platelets. | Anucleated fragments surrounded by a plasma membrane, oftenly grouped into clusters diameter varies between 2-4 microm, shape varies according to degree of activity.
Cytoplasm contains inactive peripheral hyalomere and basophilic central granulomere.
Granulomere contains lysosomes and peroxisomes; while hyalomere contains a cytoskeleton of contractile proteins (actin, mysoin, thrombosthenin) microtubules and enzymatic system for aerobic and anaerobic metabolism cytoplasm also contains glycogen and mitochondria, play a role in hemostasis (blood clotting) lifespan is about 8-12 days spleen is reserve. |
| Talk about white blood cells. | True cells having a nucleus and organelles, devoid of Hb and plasma membrane contains proteins (histocompatibility antigens MHC, HLA antigens) serving as a basis for transplant acceptance. Leukocytes participate in immune and inflammatory reactions developed by organisms to protect itself form pathogenic agents (viruses, parasites...) involved in pathological immune reactions (hypersensitivity and autoimmune diseases)
carried by blood and leave by diapedesis infiltration between endothelia, lifespan is few days (except memory T and B) 2 main categories: Granulocytes and Agranulocytes. |
| Talk about Granulocytes. | Characterized by a single nucleus presented in different lobes with different shapes and granules in cytoplasm, according to dye affinity three main groups: Eosinophil, Basophil and neurophils. |
| Talk about Neutrophils. | Most numerous ones, spherical in blood, nucleus is multi-lobed, 3-5 well individualized lobes linked by chromatin bands, cytoplasm contains few organelles and two types of granules:
Azurophilic non-specific granules (least numerous and largest (lysosomes)
Secondary specific granules (little affinity for dye, smallest and most numerous, contain mainly lysosyme and collagenase.
Mainly involved in non-specific immune responses including anti-bacterial fight by phagocytosis. lifespan is 24 hours in blood, more in organs. |
| Talk about Eosinophils | AKA acidophils, slightly larger than neutrophils, diameter between 10 and 14 microm, nucleus made of 2 lobes joined by thick chromatin, cytoplasm contains usual organelles, a small number of azurophilic granules but numerous eosinophilic granules, rounded lysosomal.
Involved in defense reactions against parasites, bactericidal and phagocytic properties, (lesser than neutrophils) participate in immediate and delayed hypersensitivity, ( IgE receptor in plasma membrane) role in regulation of histamine protein by releasing histaminase. 4-5 hours half life in blood, 8-12 days in tissues. |
| Talk about basophilic granulocytes. | Least abundant ones, diameter between 8 and 10 microm , nucleus is indistinctly lobed, irregular and can take a clover aspect (leaf like), cytoplasm contains usual organelles, and especially large basophilic granules, fewer than those of eosinophils and neutrophils covering the nucleus, granules are not considered lysosomes (heparin, histamine) plasma membrane has receptors for IgE hence a role in allergic reactions lifespan is 3=4 days. |
| Talk about Agranulocytes. | characterized by regular nucleus and a cytoplasm which does not present visible granules in optic microscopy. (lymphocytes and monocytes) |
| Talk about Lymphocytes. | Found throughout the body and in particular in lymphoid organs, loose CT and covering epithelia, only cells in the lymph. |
| Talk about lymphocyte morphoogy. | morphological aspect is characterized by
regular rounded shape, size usually small (7-8 microm) alongside small lymphocytes medium and large ones are distinguished, of moderately larger size (10 microm) nucleus is made of compact chromatin, spherical dark without visible nucleolus, occupying almost the whole cell, slightly basophilic cytoplasm reduced to a thin ring around the nucleus contains usual organelles limited quantities and some azurophilic granules. |
| What are the roles of lymphocytes? | Coordinates of body immune response, groups of three families differ by membrane antigens (T, NK, and B) |
| Talk about T lymphocytes. | Most abundant ones, involved in cell mediated immunity, maturation in thymus, characterized by presence of a protein serving as a receptor for antigens in their plasma membrane, (CD4 helper or T4) lymphocytes and CD8 (cytotoxic or T8) lymphocytes are distinguished. |
| Talk about NK lymphocytes. | non- T non B identified by NK markers, often appear of granular containing azurophilic granules. |
| Talk about B lymphocytes. | Mature in red bone marrow, characterized by presence of B receptor antigens responsible for humoral mediated immunity, in lymphoid organs they differentiate into plasma cells that synthesize antibodies (IgA, IgG, IgE, IgD, IgM) after presentation of antigen. |
| Talk about monocytes. | Main professional phagocytes, represent largest normal leukocytes in blood, shape is rounded and nucleus is bulky, central or peripheral, kidney shaped, cytoplasm is characterized by presence of some azurophilic granules (lysosomes seen by EM) organelles appear poorly developed, lifetime is very short, 24 hours in blood, in tissues they differentiate into macrophage. |
| Talk about Mastocytes. | Cells of tissues, basophilic granules and mast cells are two types of cells derive from same determined (specialized) cell precursor in red bone marrow, found in almost all loose CT, vicinity of blood vessles and nerves (more abundant in skin respiratory tract and digestive tract) Mobile, rounded with irregular contours, small rounded central nucleus, easily recognizable by basophilic granules in cytoplasm, functions are similar to basophils. |
| Talk about plasmocytes. | Differentiate from B cells in lymphoid, and hematopoietic organs and loose CT, Characteristics makes them recognizable,
Oval shaped, rounded nucleus, located at the eccentric position, with a radially shaped chromatin dispersed in large clumps at periphery (wheel radius shaped) basophilic cytoplasm occupied by a highly developed RER and voluminous Golgi apparatus, they make antibodies and do not divide and most die in days |
| Talk about macrophages. | After passage to tissues, monocytes differentiate into macrophages, size is larger than monocytes, (20 40 microm) cytoplasm is slightly eosinophilic, presents in vacuoles and lysosomes, cytoplasmic extensions that form truw pseudopodia, highly developed cytoskeleton related to extreme mobility of the cell.
Involved in all body's major defenses against foreign antigens act by phagocytosis by secretion of toxic substances and triggering immune reactions.
They are distinct from the ones present initially at the tissues. |
| Talk about Origin of Blood cells on general. | They are continuously destroyed because their life time is short in the blood and limited.
So they reproduce using Hematopoiesis in order to maintain a stable blood count.
Carried out in red bone marrow for adults present in cavities of spongy bone
All originate from multipotent cells (MSCs AKA hemocytopblasts) which are small with reduced basophilic cytoplasm and a nucleus with one or more nuclei. |
| How do MSCs differentiate? | Either divide to self renew to give birth to new ones.
Or differentiate themselves irreversibly in two major pathways:
Lymphoid stem cell gives T and B lymphocytes
Myeloid stem cell gives 5 determined cells (erythrocytes, thrombocytes, granulocytes, monocytes) |
| Talk about erythropoiesis. | Process of differentiation, proliferation and maturation that lead a stem cell to become red blood cells, done by the action of a growth factor called eryhtorpoietin. Lasts 5-7 days during this process the cell size decreases.
Myeloid stem cells-->proerythroblast--->Basophilic eruthroblast, polychromatophilic eryhtroblast (Hb synthesis color change, nucleus is denser)
--->acidophilic or orthochromatophilic eruthroblast (Hb synthesis is at its peak, nucleus is highly condensed, expelled with the organelles outside the cell)
--> Reticulocyte leaves the red bone marrow by ameboid movement contain ribosomes and mitochondria and pass to blood capillary-->in 48 Hours it becomes red blood cells or erythrocytes. |
| Talk about thrombopoiesis. | Platelets formation, regulated by stimulating factor (thrombopoietin).
Myeloid--> Megakaryoblast (basophilic cytoplasm rich in ribosomes)-->DNA replicates many times without cell division making the promegakaryocyte then formation of basophilic megakaryocyte with gaint lobed nucleus (polyploidy)-->cytoplasm is enriched with granules and becomes the thrombocytogenic megakaryocyte (large cell with huge nucleus, membrane extensions called pro platelet territories (4-8) later fragmented to make 1000 - 1500 platelets to release in a sinusoid of red bone marrow. |
