Blood & Blood Formation

Transcription

1 Module IB Blood & Blood Formation Histology and Embryology Martin Špaček, MD

2 Approximately 7% of a person's weight is blood (about 5 L) Blood consists of the formed elements and plasma

3 If blood is removed from the circulatory system, it will clot Serum: a yellow clear fluid lacking fibrinogen Blood clot: contains formed elements in a fibrin-containing network

4 Blood collected in the presence of an anticoagulant (heparin or sodium citrate) and centrifuged Plasma Buffy coat: leukocytes and plateles Red blood cells: the hematocrit 40-50% in the men 35-45% in women

5 Composition of Plasma Plasma is 92% water, about 1% ions and small soluble elements and 7% protein The main proteins: albumin globulins fibrinogen

6 Formed Elements of Blood Red blood cells (erythrocytes) White blood cells (leukocytes) granulocytes agranulocytes Platelets (thrombocytes)

7 Studying Blood Cells: Preparation of the Blood Smear Spread a drop of blood in a thin layer on a slide

8 Staining of Blood Cells After fixation, a polychromatic Romanowsky-type staining technique such as the Giemsa, Wright or Leishman method is used Four distinctive staining characteristic can be identified: basophilia (deep blue) DNA (nuclei), RNA azurophilia (purple) lysosomes eosinophilia (pink) hemoglobin in RBCs neutrophilia (salmon pink) specific granules of neutrophil leukocytes

9 Erythrocytes Biconcave disks Women average about 4.8 x 10 6 per µl Men average about 5.4 x 10 6 per µl Your body makes 2.5 million red blood cells every second

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11 Erythrocytes 7.2 µm in diameter macrocytes diameter > 9 µm microcytes diameter < 6 µm

12 Enucleated Erythrocytes endpoint of a developmental series of nucleated precursors they are terminally differentiated live about 120 days No organelles Oxygen and carbon dioxide transport only function packed with hemoglobin

13 Hemoglobin Consists of four polypeptides Each of these is attached the prosthetic group heme

14 Hemoglobin There is one atom of iron at the center of each heme

15 Hemoglobin There is one atom of iron at the center of each heme One molecule of oxygen can bind to each heme

16 Sickle Cell Disease Inherited alteration in hemoglobin Caused by a mutation of one nucleotide in the DNA of the gene for the β chain

17 Sickle Cell Disease When hemoglobin S is deoxygenated, it polymerizes and forms rigid aggregates RBCs lose their normal elasticity

18 Sickle Cell Disease Sickle cell disease results in several complications anemia pain infections stroke

19 Sickle Cell Disease Survival advantage to heterozygotes in regions of endemic malaria

20 Thrombocytes (Platelets) Cell fragments Smallest formed elements (2-4 µm in diameter) Responsible for initial clot formation Normal values: 150,000 to 400,000 per µl

21 Thrombocytes (Platelets) Hyalomere peripheral transparent zone Granulomere central zone containing purple granules Open canalicular system

22 Thrombocytes (Platelets)

23 Leukocytes Granulocytes neutrophils eosinophils basophils Agranulocytes lymphocytes monocytes

24 Neutrophiles Multilobed nucleus (polymorphonuclear) Granules in cytoplasm lysosomes Most numerous of granulocytes (60-70%) Phagocytic (microphages)

25 Neutrophiles µm in diameter

26 Neutrophiles

27 Lobulated nuclei (typically bilobed) Large granules that attract eosin stain major basic protein 2-4% of leukocytes Diameter 12-15µm Role in allergic reactions and antiparasitic functions Eosinophiles

28 Eosinophiles

29 Eosinophiles

30 Rarest cells of blood Basophils less than 1% of leukocytes Diameter µm Nucleolus divided into lobes Large specific granules attract basic dyes heparin, histamine Function in immediate hypersensitivity reactions

31 Basophils

32 Basophils

33 Lymphocytes 20-30% of leukocytes diameter 6-18 µm almost no cytoplasm nucleolus is round, condense and inactive T cells and B cells are morphologically identical in the unstimulated or resting state

34 Lymphocytes

35 Lymphocytes

36 Lymphocytes Activated B cells become plasma cells Activated T cells can become helper T cells or cytotoxic T cells

37 Monocytes 3-8% of leukocytes Large cells (12-20 µm) Nucleolus is oval and eccentrically placed More cytoplasm than lymphocyte Monocytes leave the blood and become macrophages

38 Monocytes

39 Differential Leukocytes Count Neutrophil 60-70% Eosinophil 2-4% Basophil 0.5-1% Lymphocyte 20-30% Monocyte 3-8% Changes in their relative number indicate some disorder

40 Differential Leukocytes Count

41 monocyte basophil neutrophil monocyte lymphocyte eosinophil

42 Hematopoiesis Prenatal formation of blood cells: commences in the yolk sac later, the liver and spleen become dominant sites of hematopoiesis from the 5 th month occurs in bone marrow

43 Hematopoiesis

44 Red Bone Marrow Hemopoietic cells surround the vascular sinusoids and are supported by reticular connective tissue

45 Hematopoiesis All the various types of blood cells arise from a single type of cell called a pluripotential stem cell

46 Hematopoiesis Stem cells proliferate and develop into either lymhoid multipotential cells or myeloid multipotential cells

47 Maturation of Erythrocytes Erythropoietin glycoprotein produced in the kidneys, enhances the production of RBCs Proerythroblast the first identifiable stage of erythropoiesis large, basophilic cell, which contains a large, lightly stained nulceus

48 Maturation of Erythrocytes Basophilic erythroblast strongly basophilic cytoplasm large number of polyribosomes involved in the synthesis of hemoglobin Polychromatophilic erythroblas Orthochromatic erythroblast cytoplasm filled with hemoglobin

49 Maturation of Erythrocytes The nucleolus is finally expelled The cell enters circulation as a reticulocyte, which still contains some organelles

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51 Origin of Platelets Fragmentation of the cytoplasm of megakaryocytes Megakaryocytes are very large cells (up to 160 µm) contain large, irregularly lobulated nuclei

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53 Maturation of Granulocytes Accumulation of nonspecific and specific granules Changes in nuclear morphology

54 Maturation of Monocytes Monoblast morphologically identical to the myeloblast Promonocyte large cell with basophilic cytoplasm Monocytes enter the bloodstream and then the connective tissues, where they mature into macrophages

55 Maturation of Lymphocytes All lymphocyte progenitor cells originate in the bone marrow

56 Hematopoiesis is controlled by appropriate cytokines and hormones