Blood Elements PDF

Blood Elements Dr. Sahar Khalil Prof. of Histology 1 Learning Objectives: Describe the L.M & E.M structure of blood elements: - RBCs, – WBCs, – Platelets. Differentiate between the L.M & E.M structure different types of WBCs: – Neutrophils, – Eosinophils, – Basophils,...

Blood Elements Dr. Sahar Khalil Prof. of Histology 1 Learning Objectives: Describe the L.M & E.M structure of blood elements: - RBCs, – WBCs, – Platelets. Differentiate between the L.M & E.M structure different types of WBCs: – Neutrophils, – Eosinophils, – Basophils, – Monocyte, – Lymphocytes. Relate the structure of different blood elements to their function. 2 Blood: Red, viscous, slightly alkaline fluid (pH7.4). Total volume of an adult is about 6 L (7-8% BW). Circulates in a closed system of tubes (B.V.) by the pumping action of the heart to reach the body tissues. Considered as a type of C.T. and composed of formed elements (cells) suspended in a fluid (plasma). 3 Examination of the Peripheral Blood Film: Blood film is prepared, air dried and stained with Romanovsky stains that formed of a mixture of eosin (acidic), methylene blue (basic) & related azures (basic). 4  * Components of the Blood: Plasma : 55% Formed elements : 45% It’s composition: - Erythrocytes [red blood cells (RBCs)] - Water: 90-91% - Leukocytes [white blood cells (WBCs)] - Thrombocytes (platelets) - Plasma proteins: 7-8% (albumin, globulins & fibrinogen) - Other solutes: 1-2% (electrolytes, urea, uric acid, glucose, lipids, amino acids, hormones and blood gases) Buffy coat 5 6  Formed Elements (1) Erythrocytes (RBCs): - Shape: Non-nucleated, biconcave disc shaped. Having a thick periphery and thin center. - Abnormal shape of RBCs: 1) Crenation. 2) Hemolysis. 3) Poikilocytosis. 7 (1) Erythrocytes (RBCs): - Shape of RBCs is maintained by membrane proteins: Protein 4.2 Ankyrin  Formed Elements (1) Erythrocytes (RBCs): - Size: 6-9 µm in diameter. Microcyte Normocyte Macrocyte 9 * RBCs with great variation in diameters (Anisocytosis). (1) Erythrocytes (RBCs): - Color: - Fresh RBC is greenish yellow with pale central area due to haemoglobin (Hb) content. - Stained blood film may show: - Normochromic: pink with Leishman with pale center. - Hyperchromic: deeply stained with more Hb content. - Hypochromic: pale stained with less Hb content, 10 (1) Erythrocytes (RBCs): - Number: adult male --- 4.3 - 5.7 million/ml3 adult female --- 3.9 - 5 million/ml3 - Abnormalities: a) Anaemia: decrease amount of Hb in the blood (normally 15 gm/100 ml in male and 14 gm/100 ml in female) b) Oligocythaemia: decrease in the RBCs count below normal. c) Polycythaemia: increase in the RBCs count above normal. - Life span: * about 120 days, then destroyed by macrophages in the liver, spleen. * Hb is broken into Globin & Haematin (1) Erythrocytes (RBCs): - Function: transporting O2& CO2 to and from the tissues of the body. - Structure function adaptation of RBCs: 1) Biconcave shape to increase surface area for gases exchange. 2) Highly selective cell membrane (gases exchange), 3) Highly elastic properties & stability of the cell membrane, 4) Absence of nucleus & any organelles give more space for Hb, 13 Leukocytes (WBCs): All are true cells having nuclei & organelles. Are larger and much less numerous (~700:1 ratio) than RBCs. Have shorter life span (hours to days). Cytoplasm: * Granular & * Agranular (Non-granular). Function in immunity, both cellular (T cells and phagocytic WBCs) and humoral (B cells). Total leukocytic count: 4,000 – 11,000 /mm3 Leukocytosis: * Leukopenia 1) Physiological, 2) Pathological. 14  Leukocytes Granular Agranular Lymphocyte Monocyte Neutrophil Eosinophil Basophil * Differential leucocytic count: The % of the individual types of blood leukocytes. 15  Granular Leucocytes (1) Neutrophils: - Represent 60-75 % of WBCs. - Size: 10-12 µm in diameter. - Nucleus: immature neutrophil (band form) mature neutrophil: single but segmented (multilobed), formed of 2-5 lobes interconnected by fine chromatin threads (polymorphonuclear leukocytes). * Barr body Barr body 16 - Cytoplasm: stain reddish purple (L.M.) and contain 3 types of granules (E.M.): 1) Specific granules (80%): small, contain alkaline phosphatase, collagenase & lactoferrin (bacteriostatic). 2) Azurophilic granules(20%): large, are lysosomes contain hydrolytic enzymes, proteolytic and lipolytic enzymes & peroxidase. 3) Tertiary granules: contain collagenases & gelatinases to facilitate the migration through the C.T. * Few mitochondria, Golgi complex & rER. 17 - Function: 1)First line of defence against bacterial invasion (migration & diapedesis). 2)Phagocytosis (microphage). 3)Dead neutrophils are the main cellular constituent in pus. 4)Produce pyrogens which cause fever. 5)Attraction of monocytes. 6)Stimulation of bone marrow to form new neutrophils. * - Life span: about 4 days. Neutrophilia: in acute bacterial infections as acute tonsillitis. Neutropenia: in typhoid fever, influenza & measles. 18  Granular Leucocytes (2) Eosinophils: - Represent 2- 4% of WBCs - Size: 10-12 µm in diameter - Nucleus: - bilobed connected by thick chromatin thread. - Cytoplasm: - By L.M.: Large specific granules: - By E.M.: large oval with a crystalloid body (major basic protein) and a less electron-dense matrix (histaminase, eosinophilic peroxidase). - Azurophilic granules (lysosomes). * Few mitochondria, Golgi complex & rER. 19 - Function: 1- Have an important role in allergic reactions: * phagocytosis of antigen-antibody complexes. * produce histaminase (degrade histamine & SRS-A) 2- Involved in the destruction of parasites. - Life span: In blood: few days; in C.T.: ˂ 2 weeks. Eosinophilia: in allergy & parasitic infestation. Eosinopenia: during cortisone treatment. 20  Granular Leucocytes (3) Basophils: - Represent less than 1 % of WBCs. - Size: 10-12 µm in diameter. - Nucleus: S-shaped or irregular in shape (obscured). - Cytoplasm: - By L.M.: large basophilic specific granules masking the nucleus. - By E.M.: specific spherical homogenous electron dense granules, (heparin, histamine, and ECF) & few azurophilic granules. * Few mitochondria, Golgi complex & rER. - Function: Similar to mast cells, basophils have receptors for IgE. - Life span: 1-2 days 21 Basophilia: in allergy & liver cirrhosis.  Agranular Leucocytes (1) Lymphocytes: - Represent 20-30 % of WBCs. - Rounded cells with a round nucleus and very little cytoplasm. - Types of lymphocytes (according to their size): 92% small lymphocytes (6-8 µm in diameter). Medium-sized lymphocytes (10-15 µm in diameter) Large lymphocytes (18-30 µm in diameter) - Types of lymphocytes (according to their function): 1) B-lymphocytes (15%), 2) T-lymphocytes (80%), 3) Null (N) or Natural Killer (NK) cells (5%). 22 Small Lymphocytes: Medium Lymphocytes: o Nucleus: large, central, o Nucleus: larger, indented & rounded & condensed. lightly stained. o Cytoplasm: scanty (forming o Cytoplasm: large number of a narrow rim around the mitochondria, abundant rER, nucleus), lightly basophilic well-developed Golgi complex. & non-granular. Contains numerous free ribosomes, few organelles. 23  Agranular Leucocytes - Function of T- lymphocytes: - Arise in bone marrow & differentiate in the thymus, - Function: responsible for cellular (cell mediated) immunity, - Types: T-helper cells (CD4+) & T-cytotoxic cells (CD8+) - Function of B- lymphocytes: - Arise & differentiate in the bone marrow, - Function: responsible for humoral immunity (secretion of Abs.). They must differentiate in tissue to plasma cells producing antibodies. Lymphocytosis: in T.B., viral infection (influenza) & lymphoma. Lymphopenia: in AIDS & aplastic anaemia. 24  Agranular Leucocytes (2) Monocytes: - Represent 3-8 % of WBCs - Size: 12-20 µm in diameter (the largest of blood cells), - Nucleus: large and kidney shaped. - Cytoplasm: By L.M.: faint grayish blue (frosted-glass appearance). By E.M.: numerous lysosomes and pseudopodia - Life span: about 3 days in peripheral blood & 3 months C.T. (macrophages). - Function: Highly phagocytic cells. They migrate to C.T. and differentiated into macrophages. Monocytosis: in malaria & T.B. 25 26 Platelets - Origin: from Megakaryocytes present in the bone marrow, - Size: 2-4 µm in diameter, - Shape: * Rounded to oval non-nucleated, cell fragments covered by cell membrane. - Number: 250,000-400,000 /mm3. * Thrombocytosis & Thrombocytopenia - Life span: stay in blood for about 9-10 days. 27 Platelets - Cytoplasm: By L.M.: Each has a central granular region (granulomere) & a peripheral clear region (hyalomere) By E.M.: ✓ The cell membrane: covered by glycocalyx involved in platelets adhesion. ✓ Hyalomere: it shows: 1. Microtubules 2. Actin & myosin 3. Tubules in the hyalomere ✓ Surface connecting canalicular system ✓ Dense tubular system: narrow regular tubes (Ca storage) in cytoplasm 28 Platelets - Cytoplasm: By E.M.: ✓ Granulomere: it shows: 1. Mitochondria, ribosomes, glycogen & 3 types of granules: Alpha (α) contain: – Fibrinogen, coagulation factors, – Platelet-derived growth factor Delta (dense bodies): contain: – Ca – ADP & ATP – Serotonin Lambda (175-250 nm) are lysosome (contain hydrolytic enzymes). Function: 29 Prevent bleeding from injured B.V. 30 platelets neutrophil lymphocyte RBC monocyte 31 32