University:
Texas Southern University
Course:
Biology 1407 | Biology for Science Majors II
Academic year:

2024
Views:

310

Pages:

58
Author:

Camron Firouzjahi

BLOOD CELLS Blood Major Plasma Proteins Protein Function Albumin Maintain colloid osmotic pressure , transport insoluble metabolites Globulins α and β Trranspherin,Transport metal ions, Fibronectin,Protrombin,protein-bound , lipids, lipid-soluble vitamins Globulin γ Antibodies for host defense Complement proteins Destruction of microorganisms Fibrinogen (Clotting factors) Formation of blood clots Plasma lipoproteins Transport of triglycerides and cholesterol to/from liver Blood Cells • Erythrocytes • Leukocytes – Polymorphonuclear granulocytes – Mononuclear agranulocytes • Platelets (thrombocytes) 4 Erythrocyte (Red Blood Cell,RBC) 1. Size and shape: biconcave disk, 7µm diameter, 2-3µm at thickest point, 1 µm at thinnest 2. LM appearance in smear: Pink circle with light center (center is thinner because of the biconcave shape). No nucleus. 3. TEM appearance: Solid dark gray cytoplasm, because of highly concentrated hemoglobin. Rouleaux Erythrocyte shape maintained by a cytoskeletal complex inside the plasma membrane (involving spectrin, actin and other components) flexible: RBC’s normally bend to pass through small capillaries Erythrocyte RBC Function: – Transport of oxygen and carbon dioxide • bound to hemoglobin (oxyhemoglobin and carboxyhemoglobin) • majority of CO2 transported as HCO3– pH homeostasis • carbonic anhydrase: CO2 + H2O → HCO3- + H+ • band 3 membrane protein: exchanges HCO3- for extracellular Cl• Life span in blood: About 120 days. BLOOD TYPES Sickle cell Anemia Sickle Cell Anemia Scanning electron micrograph of a sickle cell, from a person homozygous for the sickle cell mutation (Glu to Val in position 6 of beta chain of the hemoglobin molecule) 16 Hemoglobin Types • Hemoglobin HbA is most prevalent in adults, accounting for about 96% of total hemoglobin. It is a tetramer with α2β2 • Hemoglobin HbA2 accounts for 1.5% to 3% of total hemoglobin in adults. It consists of α2δ2 • Hemoglobin HbF accounts for less than 1% of total hemoglobin in adults. It contains α2γ2 and is the principal form of hemoglobin in the fetus. 17 leukocytes • Granolucytes - Neutrophil -Eosinophil -Basophil • Agranolucytes -Lymphocyte -Monocyte Granulocytes granules • Specific granules have specific functions • Azurophilic granules, which are specialized lysosomes – Myeloperoxidase which generates hypochlorite and reactive agents toxic to bacteria – Defensins which bind and produce holes in cell membranes of microorganisms – Lysozyme, which dissolves bacterial cell wall components 19 Neutrophil 60-70% 12-15 µm 2-5 Lobulated Nucleus Substances present in both primary and secondary granules: Primary (azurophilic) granules – Larger (0.5um) than secondary granules – Contain myeloperoxidase, Collagenase, lysozyme, Acid phosphatase and other enzymes • Secondary (specific) granules – Lactoferrin (binds iron), Alkaline phosphatase ,Collagenase, lysozyme • • • • • Neutrophil antibacterial activity 1. Chemotaxis and migration (chemokine synthesis and matrix proteolysis) 2. Phagocytosis and bacterial destruction • Digestion via lysozymes • Production of reactive oxygen compounds (respiratory burst) hydrogen hypochlorous acid Cl superoxide peroxide O2 NADPH oxidase* O2- superoxide dismutase • Iron sequestration via lactoferrin H2O2 myeloperoxidase HOCl *deficiency increases risk of persistent bacterial infections 3. Release factors to increase inflammatory response (and increase neutrophil production) Diapedesis Eosinophil • • • • 2-4% About 10-14 µm in diameter Bilobed nucleus The cytoplasm has prominent pink/red specific granules Eosinophil Major basic protein The specific granules are ovoid in shape, contain a dark crystalloid body composed of major basic protein (MBP), The rest of the granule contains other anti-parasitic substances and histaminase. The cytoplasm also contains lysosomes (=azurophilic granules). Phagocyte Ag Ab complex Basophil • 1% • About 12-15 µm in diameter. • The cytoplasm contains large, purple/black specific granules that are larger but not as numerous as those of eosinophils. • The nucleus is usually bilobed, but usually is partially obscured by granules, which can lie over it. Basophil Specific granules • Histamine • Heparin • Eosinophil chemotactic factor • Phospholipids for synthesis of leukotrienes, e.g. slow-reacting substance of anaphylaxis ( SRS-A ) Non-specific granules (lysosomes) • Lysozyme • Acid hydrolase • Myeloperoxidase • Elastase Function: Allergies and anaphylaxis (hypersensitivity reaction) Binding of antigens to membranebound IgE antibodies induces degranulation of specific granules, which leads to allergic reaction. In hypersensitivity reaction, widespread vasodilation (arteriolar) and vessel leakiness induce circulatory shock. Bronchial spasms cause respiratory insufficiency; combined effect is anaphylactic shock. Agranulocytes Monocyte 12-20µm,ecentric nucleus Lymphocyte 6-8µm,12µm, 18µm Lymphocyte • Spherical nuclei, indented, condensed, very basophilic chromatin, • Small (6–8 µm); medium(10-12µm); large(18-20µm) • T lymphocytes, B lymphocytes, natural killer (NK) cells Following diapedesis, only type of leukocytes can return from the tissues back to the blood 31 Monocyte • • • • • • Large(12-20µm) Ecentric nucleus, oval, kidney-shaped, or distinctly U-shaped The chromatin is less condensed The cytoplasm is basophilic and contains very small azurophilic granules Small quantity of rough ER, free polyribosomes, and many small mitochondria. A Golgi apparatus many microvilli and pinocytotic vesicles are found at the cell surfa 32 Platelets Hyalomere Granulomer 2-4µm Platelets üHyalomere (Peripheral microtubule bundle) -Dense tubular system sequesters Ca++ for signaling (similar to SR in skeletal muscle) -Open canalicular system facilitates signaling and secretion -Marginal bundle maintennce shape Platelets ü Granulomer(Cental) : Granules contain clotting factors - Alpha Granules contain PDGF,PF4,Fibrinoen,….. - Delta Granules contain ADP,ATP,ca, - Landa Granules contain lysosomic Enzymes Mitochondria for ATP production, Glycogen Transmission electron micrographs of a platelet seen in cross section (above) and in a section in the plane of the disk (below) granule membrane tubule Platelets and blood clot formation When a blood vessel wall is damaged, factors from the damaged endothelial cells and the ECM induce the clotting cascade. Platelets aggregate and release proteins for clot formation and resolution: 1. Vasoconstriction –via release of serotonin 2. Further platelet aggregation –mediated via thromboxane A2 and ADP 3. Fibrin polymerization –initiated by thromboplastin and free Ca++ thromboplastin Prothrombin Thrombin thrombin Fibrinogen Fibrin Ca++ Fibrin polymerization 4. Clot contraction –via actin, myosin, and ATP released into the matrix of the clot 5. Clot resolution –platelet plasminogen activator (pPA, converts plasminogen into active fibrinolytic plasmin) 6. Tissue repair –platelet derived growth factor (PDGF, stimulates smooth muscle and fibroblast proliferation) Platelets Clot formation Hematopoietic stem Cell 46 Stages in Red cell (Erythroid) Maturation Stages in Red cell (Erythroid) Maturation 48 Granulopoiesis Granulopoiesis Functional compartments of neutrophils 53 54 55 Platelets maturation • Platelets originate by fragmentation at the ends of cytoplasmic processes extending from giant polyploid cells called megakaryocytes in the bone marrow 56 Bone Marrow 57