Blood_Components_2023_presented.pptx

Blood Components CVI Course Dr. Gabor Szalai Email: [email protected] Objectives 1.Explain why blood is classified as a type of connective tissue, describing its specific tissue components. 2. Compare and contrast plasma with interstitial fluid, including a description of the major solutes (pro...

Blood Components CVI Course Dr. Gabor Szalai Email: [email protected] Objectives 1.Explain why blood is classified as a type of connective tissue, describing its specific tissue components. 2. Compare and contrast plasma with interstitial fluid, including a description of the major solutes (protein and non-protein) that are found in plasma. 3. Explain the significance of the structure of an erythrocyte (biconcave, lack of nucleus, lack of organelles) with respect to the function of an erythrocyte. 4. Relate the structure and function of the granulocytes (neutrophils, basophils, and eosinophils) and agranulocytes (monocytes and lymphocytes). Identify each formed element of the blood in light microscope and EM preparations. 5. Describe the development, structure, and function of the platelet and explain why it is not considered a cell. Blood • A fluid connective tissue • Adults have ~6 L of blood (7-8% of body weight) • Functions: – Exchange of gases, nutrients, and wastes with most tissues – Transporting hormones to target cells – Transporting immune cells and antibodies – Thermoregulation – Regulation of acid/base balance – Regulation of tissue extracellular fluid – Hemostasis Blood is Specialized Connective Tissue Two Components: 1. Cellular components – Erythrocytes (Red Blood Cells) – Leukocytes (White Blood cells) – Platelets (not cells, but fragments of megakaryoctye) In the adult, where are blood cells produced? Red bone marrow 2. Plasma: liquid ECM – Water – Proteins (albumin, globulins, fibrinogen, complement) – Dissolved substances (nutrients, wastes, electrolytes) When plasma leaves the circulatory system, platelets induce coagulation and it becomes viscous, yellow-tinged serum. Blood Components When coagulation is prevented (add heparin or citrate) and blood is centrifuged, it separates into 3 components: • Plasma: liquid ~55% • Buffy coat: WBCs (leukocytes) and platelets <1% • Hematocrit: RBC’s (erythrocytes) ~45% Hematocrit • Packed Cell Volume (PCV) • % of centrifuged blood volume occupied by erythrocytes • Normal hematocrit: – Men: 39% - 50% – Women: 35% - 45% • Low hematocrit is called anemia What could contribute to a low hematocrit? RBCs lost; fewer RBCs formed; decrease in RBC size What might contribute to a high hematocrit? Excess RBCs formed, prolonged low O2, severe dehydration Plasma • Primarily water • 7-8% plasma proteins – Most don’t pass through capillary walls • 1-2% small molecules (nutrients, gases, electrolytes, small proteins) – Most can pass through capillary walls Extracellular fluid of connective tissue is derived from plasma— similar electrolyte composition Plasma Proteins • Albumin (~58%) – Produced by liver – Maintains osmotic pressure – Carrier protein—thyroxine, bilirubin, fatty acids, drugs • Globulins (~37%) – Immunoglobulins (gamma globulins) = Antibodies – Nonimmune (alpha and beta globulins) • Transporter proteins (ex/transferrin, lipoproteins) • ECM structure/adhesion/repair (ex/fibronectin) • Coagulation factors (ex/prothrombin) • Fibrinogen (~4%)  fibrin during blood clotting • Regulatory proteins (<1%) – Complement: role in inflammatory response – Enzymes/proenzymes – Hormones University of Michigan Plasma proteins are retained in histological preparations  smeared, acidophilic appearance in blood vessels Blood Smear • To study blood cells histologically, we view a blood smear: thin film of blood • Typically stained with mixture of proteins dyes Stain according to – Acidic dye (eosin), charge – Basic dye (methyl blue) – Azures: dyes stain azurophilic granules (lysosomes) light purple – Common mixtures: Wright or Giemsa Progenitor cells Precursor cells Erythrocytic lineage Erythroid Precursor cells • Proerythroblast (pronormoblast): large, basophilic cell, euchromatic nucleus, pale nucleoli • Basophilic erythroblast: smaller, ribosomesbasophilia • Polychromatophilic erythroblast: blue ribosomes + pink hemoglobin • Orthochromatophilic erythroblast: more eosinophilic, with small, dark nucleus • Reticulocyte (Polychromatophilic erythrocyte): nucleus extruded, residual ribosomes 11 Reticulocytes • Special stains can be used to identify ribosomes that have not yet disappeared • Normally they make up ~1% of RBCs in the peripheral blood • In conditions of increased RBC production, circulating reticulocytes increase (up to 10-15% of RBCs) What conditions might you suspect in the case of a high reticulocyte count? Blood loss-hemorrhage, RBC destruction, high altitude Erythrocytes (Red Blood Cells) • Mature cells are anucleate & have lost their organelles • Rely on glycolysis (no mitochondria) • Filled with hemoglobin, which carries oxygen and CO2 • Biconcave in isotonic solution 7.8 um in diameter Females: 3.9-5.5 million/ul Males: 4.1-6 million/ul Netter’s Essential Histology 7.3 Central pallor Erythrocyte Membrane The structure of the erythrocyte plasma membrane gives the cell strength and flexibility-Why is this important? RBCs must squeeze through tiny capillaries! Membrane proteins (~50 % of plasmalemma): • Integral membrane proteins – Anchor the RBC membrane to the cytoskeleton – Ion transporters – Antigenic sites for blood typing – Glycophorin C, Band 3 • Peripheral membrane proteins: – Alpha and beta spectrin: form lattice on inner membrane surface, bind actin cytoskeleton – Ankyrin complex and Band 4.1 complex anchor spectrin lattice to transmembrane proteins This arrangement promotes elasticity & strength of the RBC membrane. Life Cycle of a Red Blood Cell • RBCs are a terminally differentiated, renewing cell population • Lifespan ~120 days • Worn-out cells sequestered and degraded in the liver by macrophages (some in bone marrow and spleen) Spleen Erythrocyte Abnormalities-What can go wrong? Premature RBC destruction- Hemolytic Anemias – Inherited hemoglobin defects  abnormal hemoglobin, less viable RBCs • Ex/ sickle cell disease-->fragile, misshapen cells – Defect in membrane/cytoskeletal anchoring proteins Sickled cell • Ex/ Hereditary spherocytosis: cells lose biconcave shape (small, round, no central pallor) • Weakened membrane  less flexible, fragile RBCs – Immune attack on RBCs • Immunohemolytic anemias-antibody to RBC Hereditary Spherocytosis http:// www.pathologystud ent.com/?p=1149 Erythrocyte Abnormalities-What can go wrong? • Fewer RBCs formed--Anemias of Diminished Erythropoiesis – Marrow failure/suppression (drug exposure as in aplastic anemia) – Nutrient deficiency • Impaired DNA synthesis (B12; Folate) • Iron deficiency: What might cause this? Dietary deficiency, increased requirement, impaired absorption, blood loss • Too many RBCs formed--Polycythemia – Increased red cell progenitors (P vera) – Erythropoietin-independent receptor activation Aplastic anemia (Robbins) A 28-year-old man was diagnosed at the age of 15 with a spectrin mutation. He presented to his physician with symptoms of anemia. Which of the following morphological changes to red blood cells is most likely associated with his anemia? A. B. C. D. Enlarged cells (macrocytic) Reduced hemoglobin (hypochromic) Spherical cells Sickled cells A 28-year-old man was diagnosed at the age of 15 with a spectrin mutation. He presented to his physician with symptoms of anemia. Which of the following morphological changes to red blood cells is most likely associated with his anemia? A) B) C) D) Enlarged cells (macrocytic) Reduced hemoglobin (hypochromic) Spherical cells Sickled cells As part of the patient’s evaluation, the physician will most likely check for a change in size of which organ? A. Bone marrow B. Kidney C. Lymph node D. Spleen E. Heart Leukocytes (White Blood Cells) • • • • Provide defense against pathogens and cancer cells Functional when they move out of circulation and into tissue Short-lived: hours to days Identified primarily by shape of nucleus and presence and/or type of granules: – Azurophilic (primary) granules • Lysosomes • Contain enzymes: lysozyme, acid hydrolase, elastase • Bind azurophilic dyes (light purple) – Specific (secondary) granules • Specialized secretory granules • Identified with acidic or basic stains This agranulocyte contains small, lilac azurophilic granules Leukocyte types • Granulocytes: – Contain specific (secondary) granules – Polymorphic nucleus – Mid-sized leukocytes ~12-15 mm – Include • Neutrophils (PMNs): ~49-67% of WBCs • Eosinophils: ~1-5% • Basophils: <1% • Agranulocytes: – No specific granules – Round or indented nucleus – Include • Monocytes: ~9% • Lymphocytes: 26-28% What cells will be hardest to find in a normal blood smea Neutrophils • Polymorphonuclear neutrophils (PMNs) • Part of first wave responding to injury inflammation • Primary role: phagocytosis and killing of bacteria—action of enzymes and respiratory burst • Migrate out of circulation (diapedesis) to site of wound or infection (by chemotaxis) • Lifespan: few days-1 week • Primary component of pus Neutrophil: Identification • 10-12 mm • Nucleus has 2-5 lobes • Pale-staining granules – Azurophilic granules: lysosomes – Small specific granules release enzymes and factors involved in the inflammatory response – Tertiary granules contain phosphatases and enzymes that facilitate cell migration • Cytoplasmic glycogen allows neutrophils to fight bacteria in poorly oxygenated tissues Barr Body Inactivated Xchromosome-- present in females Netter’s Essential Left Shift As granulocytes differentiate, the nucleus forms a long band, and later lobulates. These maturing cells are called “band cells.” The term, left shift is used to describe an increase in band cells in circulation. What might a lab finding of a neutrophilic left shift indicate? Bacterial infection, tissue injury Neutrophil Band cell Eosinophil • Role in defense against helminths (parasitic worms) • Associated with allergic reactions & chronic inflammation – Pathology shows numerous eosinophils in CT of affected organs-intestines, lungs • Mediate immune response: – Phagocytose antigen-antibody complexes – Help to moderate effects of inflammatory mediators (release histaminase) Eosinophil: Identification • 10-12 mm • Bilobed nucleus • Azurophilic granules • Numerous larger, eosinophilic specific granules – Crystalloid core of major basic protein: cytotoxic effects on parasites – Other enzymes & cytotoxic proteins Specific granule components, such as histaminase & arylsulfatase can neutralize secretions of mast cells & basophils Junqueira Netter’s Essential Histology Basophil • Function similar to mast cells; supplement mast cell function when they migrate into connective tissues • Degranulate in response to allergen, releasing vasoactive agents & inflammatory mediators • May produce powerful inflammatory response upon second exposure to allergen—anaphylaxis • Involved in type 1 hypersensitivity reactions Basophil: Identification • 10-12 mm in diameter • Nucleus has 2-3 lobes • Granules: – Azurophilic granules – Very large basophilic specific granules • Heparin (sulfated GAG, anticoagulant) • Histamine (inflammatory mediator) • Leukotrienes (promote airway SM constriction) Lymphocyte • Key player in adaptive immune system • Functional groups—indicated by cell surface markers (e.g. B-cells, T-cells, & NK cells) • Circulate among blood, tissues, & lymph • Able to divide and differentiate into effector cells • Roles in fighting microbes or cancer cells; antibody production via plasma cells Lymphocyte: Identification • • • • Most are small (6-8 mm) Spherical nuclei Scant, slightly basophilic cytoplasm Lymphocyte types cannot be readily distinguished in a routine blood smear How can clinicians or researchers distinguish the different types of lymphocytes? Immunohistochemistry or flow cytometry Monocyte • Precursor cells of the mononuclear phagocytic system • Circulating cells that differentiate into macrophages and similar cells in tissues • Remain in blood about 3 days • Major functions: – Phagocytosis of microbes & debris – Antigen-presenting cells Monocyte: Identification • • • • Larger leukocytes (~18mm) Indented or kidney-bean shaped nucleus Abundant cytoplasm Small azurophilic granules Macrophage • Note: not classified as a blood cell • Present in connective tissues; differentiate from monocytes recruited during inflammatory response • Phagocytose pathogens, debris and dead cells • Antigen-presenting cells • Abundant in CT in chronic inflammation • Similar cells specialized to specific tissues: – Microglia in CNS – Osteoclasts in bone – Dust cells (alveolar macrophages) in lungs – Kupffer cells in liver Leukocyte Abnormalities-What can go wrong? • Leukocyte proliferative conditions – Reactive: response to microbial infection – Neoplastic: malignancies of white cells and their progenitor cells • Deficiency of leukocytes- leukopenias: – Drug toxicity – Autoimmune and immunodeficiency diseases Platelets (Thrombocytes) • ~1.5-3.5 mm membrane-bound cytoplasmic fragments of a megakaryoctye • Peripheral marginal bundle of microtubules and actin filaments maintain disc shape • Dark staining central region (granulomere) contains granules with clotting factors and growth factors • Pale staining outer region (hyalomere) contains invaginations of cell membrane and vesicles that facilitate rapid degranulation • Lifespan ~10 days Megakaryocyte • Found in bone marrow adjacent to sinusoids • Megakaryoblasts replicate DNA, but do not divide  megakaryocytes are polyploid cells • Demarcation channels throughout the peripheral cytoplasm facilitate partitioning of fragments • Cytoplasmic fragments pinch off in sinusoids releasing platelets into circulation Platelet Abnormalities-What can go wrong? • Thrombocytopenia – Decreased production (drugs, bone marrow failure) – Decreased survival (immune destruction, intravascular coagulation) – Dilution (transfusion) What symptoms would you expect to see in thrombocytopenia? Increased bleeding, bruising, petichiae Petechial Rash Pediatrics A Competency-Based Companion . Singh, Sabina B., MD. 2011. Figure 98-1 Thank you for your attention!