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PG1006 Lecture 8 Haematology 1-‐Composi:on of Blood Dr. Neil Docherty 25/11/09 My Teaching Objec:ves • To describe blood as a specialised connec:ve :ssue comprised of a cellular emulsion • The outline the composi:on of the formed (cells) and non-‐ formed (plasma) elements of blood • To outline the histological features and func:on of leukocytes Blood Basics A mobile, circulatory :ssue comprising of a variety of cells suspended in a fluid called plasma Via co-‐opera:on with major organ systems acts as vehicle for, 1) Gas transport and exchange 2) Heat exchange 3) Nutrient and waste product exchange 4) Endocrine cell-‐cell communica:on 5) Circula:on of body defense system Liquid/Cellular Phases FRESH BLOOD (+ an:coagulant) post-‐centrifuga:on PLASMA WHITE BLOOD CELLS PLATELETS RED BLOOD CELLS, >50% of blood volume(3L) 20% of ECF Packed Cell Volume (PCV) 40-‐50% M 37-‐47% F Blood Plasma Characteris:cs • 92% ionic solu:on (major osmo:c species Na+ and Cl-‐) • 290mOsm (same as ECF inters::al fluid) • Normal pH 7.35-‐7.45 (venous blood lower ++HCO3-‐) • 8% protein The Plasma Proteins ALBUMIN (60%) -‐Binding of rela:vely insoluble components for transport (e.g. faey acids) GLOBULINS (40%) Alpha1-‐4% Alpha 2-‐8% Beta-‐12% Gamma-‐16% Specific binding proteins, (iron carriers, cholesterol) Inac:ve pre-‐hormones and clogng factors Immunoglobulins (soluble an:body) All above contribute to the maintenance of circulatory volume by exer:ng a plasma onco:c pressure Blood Cell Basics RED CELLS (ERYTHROCYTES) AND PLATELETS (99.9%) Red blood cells (erythrocytes) deliver oxygen around body bound to haemoglobin Platelets (fragments of megakaryocytes) assist in the forma:on of a plug over sites of vascular damage and local vasoconstric:on WHITE CELLS (LEUKOCYTES) (0.1%) Divided into 5 classes. Used to fight infec:on in the body Erythrocytes • Biconcave discs • Small diameter • No nuclei or organelles • Packed with haemoglobin • 120 day life span • Clearance in spleen Prompt-‐What cell type in the spleen is important for clearance of worn out erythrocytes?? Erythropoiesis In adults, made from stem cells in the red bone marrow of flat bones Emerge into bloodstream • TAKES 7 DAYS • CIRCULATE FOR 120 DAYS Control of Erythropoiesis Prompt-‐What cell type in the kidney makes erythropoie:n?? Platelets • Small non-‐nucleated cells (do contain organelles) • Fragments derived from megakaryocyte precursor • Plug vascular leaks, template for clot assembly, release vasoconstrictory and clogng substances (e.g. serotonin, fibrinogen) Leukocytes 1. POLYMORPHONUCLEAR GRANULOCYTES Neutrophil (70%) Basophil(1%) Eosinophil (4%) cell ea:ng (phagocytosis) allergic responses allergic responses (histamine) protec:on from parasites 2. LYMPHOCYTES Natural Killer Cells, B-‐Cells and T-‐cells (20%) T cells can directly kill invading viruses and bacteria or help B cells make an:body or granulocytes/monocytes to non-‐specifically kill 3.MONOCYTES 5% of leukocytes Have highest capacity to eat invaders when they become ac:vated to macrophages. All :ssues have their resident macrophages e.g) Kuppfer cells in liver Neutrophils • 70% WBC • Acute inflamma:on • Primary • Secondary granules • Ter:ary Eosinophils • >4% of WBC • Enter mucosal surfaces • Increased in parasi:c allergic disease • Phagocytose IgE opsonised parasites (Find out what this means exactly) • Also kill by granule release Basophils • >1% of WBC • Increased in parasi:c/allergic disease • Exocytose granules (histamine)via contact with IgE complexed allergen Histamine dilates blood vessels (inflamma:on-‐redness) Lymphocytes 20% of WBC • Cooperate with an:gen presen:ng cells • Wide variety of adap:ve, specific responses. B-‐lymphocytes-‐an:body produc:on (plasma cells) an:gen presenta:on T-‐lymphocytes-‐priming of innate responses (T-‐helper 1) -‐priming of an:body responses (T-‐helper 2) -‐Direct cell lysis (cytotoxic T’s) ac:vated Monocytes 5 % of WBC • Migrate to peripheral :ssues to become macrophages • Effec:ve at phagocytosis and an:gen presenta:on to T-‐lymphocytes • Free and fixed types • Resident fixed types specific to organs e.g-‐ 1) Kupffer cell-‐liver 2) Dust cell-‐lung 3) Langerhans cell-‐skin 4) Microglia-‐C.N.S. Leukocyte and Platelet Haemopoiesis 4 unipotent lineages Lymphocyte matura:on Occurs outside marrow T-‐lymphocytes-‐thymus B-‐lymphocytes-‐spleen Summary of Blood Cell Characteris4cs Your Learning from Today Should focus on being able to; 1) Describe the composi:on of the formed and non-‐formed elements of the blood 2) Explain the features and func:ons of erythrocytes 3) Explain the features and func:ons of leukocytes
