BLOODDepartment of histology, cytology and embryology2013 medical students Kharkov National Medical University
Blood: consists ofCells:Erythrocytes (RBC)Leucocytes (WBC)Thrombocytes (Platelets)+
Plasma (fluid intercellular space)
Cells of the BLOOD
Blood cells. Erythrocytes
ERYTHROCYTESAmount in bloodMen - 3.9 - 5.5 1012/literWomen - 3,7-4,9 1012/liter
Erythrocyte : biconcave discwith average diameter ~ 7 m (!!!).does not contain a nucleusis filled with hemoglobin - the oxygen binding protein
function of ERYTHROCYTEErythrocytes Are Involved in Body-wide Transport of Oxygen and Carbon Dioxide.
In the lungs, the hemoglobin in erythrocytes readily combines with oxygen and becomes oxyhemoglobin.Erythrocytes are also involved in the transport of carbon dioxide from the tissues to the lungs; this function depends on the content of the enzyme carbonic anhydrase.
function of ERYTHROCYTE: carries oxygen from the lungs to the body cells,helps in carrying of CO2 from tissues to the lungs!!! NOTE: biconcave shape improves exchange by decreasing of diffusions distance !!!
ERYTHROCYTESerythrocytes abnormalities :
an erythrocyte, smaller than6 m in diameter is termed amicrocyte;whereas an erythrocyte larger than normal (from 9 m to 12 m in diameter) is termed a macrocyte
Thus a shift in size range toward smaller erythrocytes is called a microcytic condition, and toward bigger ones, a macrocytic condition.
Smears of normal blood usually exhibit an occasional erythrocyte of abnormal shape. The general term for such a cell is a poikilocyte (Gr. poikilis, manifold).
Unisocytosis and Poikilocytosis 1 discocytes -normocytes; 2 MACROCYTE; (may be microcyte, 2 types of un-iso-cytosis)3,4 echinocytes; 5 stomatocyte; 6 sferocytes.3-6 - poikilocytosis3516
PlateletsThey are: membrane-bound sacs, fragments of cells;
2 to 5 m in diameter.
PLATELETSPlatelets Play a Key Role in the Arrest of Bleeding (Hemostasis, blood clotting)
PlateletsConsist of 2 zones:- peripheral one is called the Hyalomere.The central one - Granulomere. Hyalomere is a colorless and homogeneous.granulomere contains azure-colored granules.
PlateletsThe granules contain several different substances:thromboplastin promotes blood clotting serotonin elicits pain
platelet-derived growth factor (PDGF) - stimulates tissue regeneration
LeucocytesTrue cells, have nucleus, organelles and inclusions in granulesALL Leucocytes migrare from blood to connective tissueNucleus containes two to eight lobes
Classification:types by presence of granules !!! Totally 5 types of leucocytes Granulocytes neutrophils, basophils,eosinophils
Basophils Eosinophils Neutrophils
Cytoplasm contains granules. These granules have different stain affinity which allows the granulocytes to be placed into three categories:
Basophils Eosinophils Neutrophils
BasophilsThe basophilic granules are large, stain deep blue to purple, and are often so numerous that they mask the nucleus. Basophils constitute only approximately 0.5% of peripheral blood leukocytes.
BasophilsThese granules contain histamine (cause vasodilation) and heparin (anticoagulant).
Eosinophilshave large acidophilic granules which appear pink (or red). The granules contain digestive enzymes that are particularly effective against parasitic wormsThese cells also phagocytize antigen-antibody complexes.
Eosinophils EM image
Neutrophils12 to 14 m in diameter.Granules are pale staining (neutral) They play primary role in inflammation.They are capable for phagocytosis of bacteria.
The segmented nucleus of most neutrophils consists of two to five lobes interconnected by fine strands of chromatin.
In mature neutrophils, sex chromatin (where present) can sometimes be seen as a separate tiny lobe known as a drumstick appendage.
The cytoplasm of mature neutrophils contains two kinds of granules azurophilic granules and specific granules
LEUKOCYTESLymphocytes comprise 20% to 50% of the blood leukocytes
LymphocytesNucleus is very large, almost fills the cell leaving a very thin rim of cytoplasm. Function - immune response.
2 types: The B-lymphocytes: go to connective tissue to become PLASMA Cell. produce antibodies, The T-lymphocytes act against virus-infected cells and tumor cells.
Monocytes- are the largest among the leukocytes, about 20 m in diameter and agranular. The nucleus is most often U-shaped or kidney-bean -shaped, or C-shapedthe cytoplasm is abundant and light blue.
Monocytes comprise from 3% to 11% of the blood leukocytes
These cells leave the blood stream to become macrophages in conn. tiss. macrophages play a role in inflammatory and immune responses. are antigen-presenting cells (APC)They are phagocytes, defend the body against viruses and bacteria.
Complete Blood Count (CBC)
CharacteristicsAmountHematocrit men0,39-0,49Hematocrit women0,35-0,45RBC men4,0-5,0 1012/LRBC women3,9-4,7 1012/LHb men13-16 g/dLHB women12-14 g/dLWBC4-9 109/LPlatelets180-320 109/L
White Blood Cell Differential Count
Basos Eos Segs Lymphs Monos Myelo-cytes Meta-myelo-cytesBands Seg-mented 0-1% 0,5-5% --- --- 1-6% 47-72% 19-37% 3-11%
Blood Cell formation(haemocytopoiesis)
HaemopoiesisDuring fetal development, the formation of blood cells (haemopoiesis) begins in the wall of the yolk sac. After the second month of fetal development, the liver, and, slightly later, the spleen, become the dominant sites of haemopoiesis. From the 6th month the formation of blood cells occurs in bone marrow,
Haemopoietic CellsThere are 6 classes of Haemopoietic Cells
1 classStem cells 1-st class
-- self-replicating, which can generate all types of blood cells.
2 classProgeny of stem cells may develop into either lymphoid semi-stem cells (gives rise to lymphocytes) or myeloid semi-stem cells (gives rise to the major groups of blood cells other than lymphocytes )
Note: semi-stem cells:- are particularly determined cells: are capable to develop only into lymphocytes or only into all other blood cells. Development of blood cells from LSC is called lymphopoiesis. Development of blood cells from MSC is called myelopoiesis.
3 class is calledunipotential or hemopoietin-sensitive cells.
Myeloid linesMyeloid semi-stem cell forms 4 kinds of hemopoietin-sensitive cells:Erythropoietin-sensitive cell forms the erythroid line Leukopoietin-sensitive cell forms granulocytes lineMonopoietin-sensitive cell forms monocyte - macrophages line Thrombopoietin-sensitive cell forms megakaryocytes --- thrombocyte line
Lines of lymphopoiesisB- lymphopoiesis T- lymphopoiesis
4-th class of Haemopoietic CellsThe first recognizable, actively dividing cells that are called blast cells.
4. Haemopoietic CellsThere are six types of blast cells:Proerythroblast or simply erythroblast;Myeloblast;B- lymphoblast;Megakaryoblast;MonoblastT- lymphoblast;
5th class of Haemopoietic Cells- cell differentiation
6th class of Haemopoietic CellsMature cell - leave RBM and Thymus and go to bloodstream
Erythroid line The first identifiable stage of erythropoiesis is the proerythroblast - a large, slightly basophilic cell, which contains a large, lightly stained nulceus.
Erythrocytes Proerythroblasts differentiate to: basophilic erythroblast, polychromatophilic and orthochromic normoblasts. The nucleus is finally extruded from the normoblast.
See: Erythrocytes of frog, NucleatedPrimitive!In human only during formation, in bone marrow - normoblasts
Reticulocyteyoung erythrocytes still contain some organelles, may enter circulation remain for a few days in the bone marrow to mature to erythrocytes
Erythrocyte is leaving RBM
Granulocytes Myeloblasts proliferate to generate promyelocytes. Promyelocytes begin to accumulate nonspecific granules, but they are still able to divide. The maturation of their progeny, the Myelocytes, young leucocytes, are characterised by the accumulation of specific granules and changes in nuclear morphology. Metamyelocytes have C-shaped nucleus.
Blood Platelets (Thrombocytes)Are formed from giant myeloid cells called megakaryocytes (60 to 160 m in diameter). Cytoplasmic processes of these cells extend into marrow sinuses and fragment away. These cellular fragments are the platelets or thrombocytes.
Megakaryocytes are in turn the product of the differentiation of basophilic megakaryoblasts.