Chapter 19: Blood Cells and Clotting PDF

White Blood Cells (WBCs) = 5-10 thousand per mm3 Granulocytes large granules & lobed nuclei neutrophils, eosinophils, basophils Agranulocytes granules not easily seen under scope lymphocytes, monocytes © McGraw Hill, LLC...

White Blood Cells (WBCs) = 5-10 thousand per mm3 Granulocytes large granules & lobed nuclei neutrophils, eosinophils, basophils Agranulocytes granules not easily seen under scope lymphocytes, monocytes © McGraw Hill, LLC 26  Standard Blood Smear Ed Reschke/Stone/Getty Images © McGraw Hill, LLC 27  Characteristics of WBCs 1. protect body from invading microorganisms 2. remove dead cells & debris from body How they accomplish this: ameboid movement: directed movement using pseudopodia diapedesis: cells leave blood stream by becoming thin, elongating & moving either between or through endothelial cells of capillaries chemotaxis: attraction to & movement toward foreign materials or damaged cells via chemical sensing accumulation of dead white cells & bacteria = pus © McGraw Hill, LLC 28  Neutrophils – polymorphonuclear neutrophils (PMNs) 55-70% of [WBC] circulate 10-12 hrs & move into other tissues last 1-2 days secrete lysozyme become motile, phagocytize bacteria, antigen-antibody complexes & other foreign matter (a) Alvin Telser/McGraw Hill; © McGraw Hill, LLC 29  Eosinophils 1-4% of [WBC] circulate for 8-18 hrs last 2-5 days in tissues granules stain red w/ eosin enter tissues during inflammatory response prevalent in allergic reactions destroy inflammatory chemicals like histamine protect against tapeworms, (b) BioPhoto Associates/Science Source; flukes, pinworms & hookworms © McGraw Hill, LLC 30  Basophils (least common) < 0.5-1% of [WBC] last 2-3 days in blood or tissues granules stain blue or purple migrate through tissues & play role in both inflammatory & allergic reactions produce histamine (increases inflammation) produce heparin (inhibits (c) Alvin Telser/McGraw Hill blood clotting) © McGraw Hill, LLC 31  Lymphocytes 20-40% of [WBC] lifespan of weeks to months but variable once activated produced in red bone marrow proliferate in lymphatic tissues antibody production (B cells) destruction of virus & other microorganism-infected cells (d) Alvin Telser/McGraw Hill (T cells) © McGraw Hill, LLC 32  Monocytes 2-8% of [WBC] circulate for 3 days leave circulation & become macrophages or dendritic cells may last for weeks- months break down antigens & present them to lymphocytes for recognition (e) Ed Reschke/Stone/Getty Images © McGraw Hill, LLC 33  Platelets = 150-400 thosuand per mm3 cell fragments from megakaryocytes in red bone marrow surface glycoproteins & proteins allow adhesion to other molecules such as collagen important in preventing blood loss platelet plugs promoting formation & contraction of clots last 5-9 days © McGraw Hill, LLC 34  Formed Elements of the Blood TABLE 19.2 Formed Elements of the Blood Cell Type Illustration Description Function Abundance (cells/μL)* Red Blood Cell Biconcave disc; no nucleus; Transports O2 and CO2 4.2–5.4 million contains hemoglobin, which (females) A red blood cell has the shape of a flat disk or doughnut, which is round with an indentation in the center but is not hollow. colors the cell red; 7.5 μm in 4.7–6.1 million diameter (males) White Blood Spherical cells with a nucleus Five types of white blood 4500–11,000 Cells cells, each with specific functions Granulocytes Neutrophil Nucleus with two to five lobes Phagocytizes 55–70% of WBC connected by thin filaments; microorganisms and Neutrophil is the smallest of all granulocytes with a characteristic multi-lobed nucleus with 3-5 lobes joined by slender strand of genetic material. cytoplasmic granules stain a other substances light pink or reddish-purple; 10–12 μm in diameter Eosinophil Nucleus often bilobed; Attacks certain worm 1–4% of WBC cytoplasmic granules stain parasites; releases orange-red or bright red; 11– chemicals that modulate 14 μm in diameter inflammation; negatively An eosinophil has a nucleus with two lobes (bilobed) and a cytoplasm filled with approximately 200 large granules. impacts airways during asthma attacks © McGraw Hill, LLC 35  Formed Elements of the Blood TABLE 19.2 Formed Elements of the Blood Cell Type Illustration Description Function Abundance (cells/μL)* Basophil Nucleus with two indistinct Releases histamine, which 0.5–1% of WBC A basophil is a polymorphonuclear cell with a polylobed nucleus and prominent, brightly metachromatic cytoplasmic granules. lobes; cytoplasmic granules promotes inflammation, and stain blue-purple; 10–12 μm heparin, which prevents clot in diameter formation Agranulocytes Lymphocyte Round nucleus; cytoplasm Produces antibodies and other 20–40% of WBC forms a thin ring around the chemicals responsible for nucleus; 6–14 μm in destroying microorganisms; A lymphocyte is an agranular cell with a very clear cytoplasm that stains pale blue. Nucleus is very large for the cell size and stains dark purple. diameter contributes to allergic reactions, graft rejection, tumor control, and regulation of the immune system Monocyte Nucleus round, kidney- Phagocytic cell in the blood; 2–8% of WBC shaped, or horseshoe- leaves the blood and becomes shaped; contains more a macrophage, which A monocyte has an irregular cell shape, an oval or kidney-shaped nucleus, cytoplasmic vesicles, and a high nucleus to cytoplasm ratio. cytoplasm than lymphocyte phagocytizes bacteria, dead does; 12–20 μm in diameter cells, cell fragments, and other debris within tissues Platelet Cell fragment surrounded by Forms platelet plugs; releases 150,000–400,000 A platelet is irregularly shaped and has no nucleus. plasma membrane and chemicals necessary for blood containing granules; 2–4 μm clotting in diameter *White blood cell counts are listed as percentage of total white blood cells. © McGraw Hill, LLC 36  Hemostasis – arrest of bleeding Preventing excessive blood loss involves: 1. Vascular spasm: vasoconstriction of damaged blood vessels, occlusion of small vessels caused by thromboxanes from platelets & endothelin from damaged endothelial cells 2. Platelet plug formation 3. Coagulation or blood clotting © McGraw Hill, LLC 37 © McGraw Hill, LLC  Platelet Plug Formation can seal small breaks in vessels activated platelets release platelet factor III & coagulation factor V needed for clot formation 1. Platelet adhesion platelets bind to collagen exposed when a blood vessel is damaged most mediated via protein von Willebrand factor (vWF) produced & secreted by blood vessel endothelial cells platelets have surface receptors for vWF released from damaged vessels vWF also binds to exposed collagen of damaged vessel & forms a bridge between exposed collagen & platelets other platelet surface receptors can bind directly to collagen © McGraw Hill, LLC 39  Platelet Plug Formation 2. Platelet release reaction: binding to collagen activates platelets release ADP, thromboxanes & other chemicals by exocytosis ADP & thromboxane bind to receptors on surfaces of other platelets & activate them these activated platelets release additional chemicals → cascade of chemical release by platelets → more platelets activated (positive feedback) © McGraw Hill, LLC 40  Platelet Plug Formation 3. Platelet aggregation activated platelets change shape & express fibrinogen receptors fibrinogen forms a bridge between fibrinogen receptors of different platelets = platelet plug © McGraw Hill, LLC 41  Figure 19.10 ADP Thromboxane Platelet aggregation 3 Platelet Platelet release 2 reaction Fibrinogen Granules Endothelial Platelet adhesion cell 1 Fibrinogen receptor von Willebrand factor Collagen Blood vessel wall Smooth muscle cell Platelet plug © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC.  Coagulation Stages 1. Activation of prothrombinase 2. Conversion of prothrombin to thrombin 3. Conversion of fibrinogen to fibrin Clotting factors: plasma proteins circulate inactive until tissue injury damaged tissues & platelets activate clotting factors Pathways Extrinsic Eye of Science/Science Source Intrinsic Result: blood clot network of threadlike fibrin, trapped blood cells, platelets & fluid © McGraw Hill, LLC 43  Clotting Pathways Extrinsic pathway: begins w/ chemicals outside of blood damaged tissues release tissue factor (TF; factor III) when Ca2+ present → forms complex w/ factor VII → activates factor X Intrinsic pathway: begins w/ chemicals within blood in damaged blood vessels factor XII reacts to exposed collagen → activates factor XII stimulates factor XI → activates factor IX activated factor IX combines w/ factor VIII, platelet phospholipids & Ca2+ to activate factor X © McGraw Hill, LLC 44  Common Pathway prothrombinase formed from extrinsic &/or intrinsic pathways converts prothrombin → thrombin thrombin converts fibrinogen → fibrin thrombin activates factor XIII to stabilize clot Vitamin K required for formation of many clotting factors © McGraw Hill, LLC 45  Clot Formation 1. Extrinsic pathway i. damaged tissues release mixture of lipoproteins & phospholipids (thromboplastin or tissue factor (TF) or factor III ii. in presence of Ca2+ thromboplastin complexes w/ factor VII → activates factor X → initiates common pathway © McGraw Hill, LLC 46  Clot Formation 2. Intrinsic pathway: i. damaged blood vessels exposes collagen beneath blood vessel endothelium ii. plasma factor XII interacts w/ collagen to activate iii. activated factor XII → factor XI to activate factor IX iv. activated factor IX joins w/ factor VIII, platelet phospholipids & Ca2+ → activates factor X to initiate common pathway once thought distinct it is now known that activated factor VII from extrinsic pathway can stimulate formation of activated factor IX in intrinsic pathway © McGraw Hill, LLC 47  Clot Formation 3. Common pathway: activation of extrinsic &/or intrinsic pathways results in activated factor X 4. Prothrombinase (activated factor X, factor V, platelet phospholipids & Ca2+) formed on surface of platelets aka prothrombin activator 5. xThrombin produced prothrombinase converts plasma protein prothrombin to enzyme thrombin © McGraw Hill, LLC 48  Clot Formation 6. xFibrin produced: thrombin converts soluble plasma protein fibrinogen to insoluble fibrin forms the fibrous network of a blood clot 7. Positive-feedback effects of thrombin: thrombin also stimulates factor XIII activation to stabilize the clot thrombin also activates many clotting proteins (factor XI & prothrombinase positive-feedback system = thrombin stimulates production of additional thrombin & has a positive-feedback effect on platelet aggregation by stimulating platelet activation © McGraw Hill, LLC 49  Clot Formation © McGraw Hill, LLC 50 TABLE 19.3 Clotting Factors Factor Number Name (Synonym) Description and Function I Fibrinogen Plasma protein synthesized in the liver; converted to fibrin in the common pathway II Prothrombin Plasma protein synthesized in the liver (requires vitamin K); converted to thrombin in the common pathway III Thromboplastin (tissue factor) Mixture of lipoproteins released from damaged tissue; required in the extrinsic pathway IV Calcium ion Required throughout the clotting sequence V Proaccelerin (labile factor) Plasma protein synthesized in the liver; activated form functions in the intrinsic and extrinsic pathways VII Serum prothrombin conversion Plasma protein synthesized in the liver (requires vitamin accelerator (stable factor, K); functions in the extrinsic pathway proconvertin) VIII Antihemophilic factor Plasma protein synthesized in megakaryocytes and (antihemophilic globulin) endothelial cells; required in the intrinsic pathway IX Plasma thromboplastin Plasma protein synthesized in the liver (requires vitamin component (Christmas factor) K); required in the intrinsic pathway X Stuart factor (Stuart-Prower Plasma protein synthesized in the liver (requires vitamin factor) K); required in the common pathway Note: Factor VI was once thought to be involved but is no longer accepted as playing a role in clotting; it is apparently the same as activated factor V. © McGraw Hill, LLC 51 TABLE 19.3 Clotting Factors Factor Number Name (Synonym) Description and Function XI Plasma thromboplastin Plasma protein synthesized in the liver; required in the antecedent intrinsic pathway XII Hageman factor Plasma protein required in the intrinsic pathway XIII Fibrin-stabilizing factor Protein found in plasma and platelets; required in the common pathway Platelet Factors (released by platelets during the intrinsic pathway) I Platelet accelerator Same as plasma factor V II Thrombin accelerator Accelerates thrombin and fibrin production III Phospholipids necessary for the intrinsic and extrinsic pathways IV Binds heparin, which prevents clot formation © McGraw Hill, LLC 52  Control of Clot Formation coagulation occurs when coagulation factor concentration exceeds threshold (occurs at site of injury) anticoagulants: prevent coagulation factors from initiating clot antithrombin: produced by liver & slowly inactivates thrombin prostacyclin: prostaglandin-derived from endothelial cells causes vasodilation & inhibits release of coagulating factors from platelets outside of body (i.e. for transfusions): use heparin, EDTA, sodium citrate © McGraw Hill, LLC 53  Clot Retraction & Dissolution clot retraction: clot condenses into compact structure platelets contain actin & myosin to aid in contraction serum released as clot contracts edges of damaged blood vessel pulled together → fibroblasts & epithelial cells begin repair process clot dissolution: clot dissolves over time via fibrinolysis plasmin hydrolyzes fibrin can be activated by t-P A, urokinase, or *streptokinase © McGraw Hill, LLC 54