Chapter 19: The Cardiovascular System: The Blood

Transcription

1 Blood Chapter 9: The Cardiovascular System: The Blood Liquid connective tissue general functions. Transportation Gases, nutrients, hormones, waste products. Regulation ph, body temperature, osmotic pressure. Protection Clotting, white blood cells, proteins Components of Blood Blood plasma water liquid extracellular matrix 9.5% water, 8.5% solutes (primarily proteins) Hepatocytes synthesize most plasma proteins Albumins, fibrinogen, antibodies Other solutes include electrolytes, nutrients, enzymes, hormones, gases and waste products Formed elements cells and cell fragments Red blood cells (RBCs) White blood cells (WBCs) Platelets Formed Elements of Blood Formation of Blood Cells Negative feedback systems regulate the total number of RBCs and platelets in circulation Abundance of WBC types based of response to invading pathogens or foreign antigens Hemopoiesis or hemotopoiesis Red bone marrow primary site Pluripotent stem cells have the ability to develop into many different types of cells

2 Formation of Blood Cells Stem cells in bone marrow Reproduce themselves Proliferate and differentiate Cells enter blood stream through sinusoids Formed elements do not divide once they leave red bone marrow Exception is lymphocytes Formation of Blood Cells Red Blood Cells/ Erythrocytes Pluripotent stem cells produce Myeloid stem cells Give rise to red blood cells, platelets, monocytes, neutrophils, eosinophils and basophils Lymphoid stem cells give rise to Lymphocytes Hemopoietic growth factors regulate differentiation and proliferation Erythropoietin RBCs Thrombopoietin platelets Colony-stimulating factors (CSFs) and interleukins WBCs Contain oxygen-carrying protein hemoglobin Production = destruction with at least million new RBCs per second Biconcave disc increases surface area Strong, flexible plasma membrane Glycolipids in plasma membrane responsible for ABO and Rh blood groups Lack nucleus and other organelles No mitochondria doesn t use oxygen Hemoglobin Shapes of RBC and Hemoglobin Globin 4 polypeptide chains Heme in each of 4 chains Iron ion can combine reversibly with one oxygen molecule Also transports % of total carbon dioxide Combines with amino acids of globin Nitric oxide (NO) binds to hemoglobin Releases NO causing vasodilation to improve blood flow and oxygen delivery

3 Red Blood Cells Formation and Destruction of RBC s RBC life cycle Live only about 0 days Cannot synthesize new components no nucleus Ruptured red blood cells removed from circulation and destroyed by fixed phagocytic macrophages in spleen and liver Breakdown products recycled Globin s amino acids reused Iron reused Non-iron heme ends as yellow pigment urobilin in urine or brown pigment stercobilin in feces Circulation for about 0 days 7 Amino Reused for acids protein synthesis Fe Globin Transferrin Fe Heme Ferritin Fe Biliverdin Red blood cell death and phagocytosis Macrophage in spleen, liver, or red bone marrow 9 Bilirubin Urine Kidney Urobilin Transferrin Bilirubin Liver 0 Small intestine Bilirubin Urobilinogen Bacteria Stercobilin Large 4 intestine Feces Globin Vitamin B Erythopoietin 8 Erythropoiesis in red bone marrow Key: in blood in bile Erythropoiesis Starts in red bone marrow with proerythroblast Cell near the end of development ejects nucleus and becomes a reticulocyte Develop into mature RBC within - days Negative feedback balances production with destruction Controlled condition is amount of oxygen delivery to tissues Hypoxia stimulates release of erythropoietin White Blood Cells/ Leukocytes Types of White Blood Cells Have nuclei Do not contain hemoglobin Granular or agranular based on staining highlighting large conspicuous granules Granular leukocytes Neutrophils, eosinophils, basophils Agranular leukocytes Lymphocytes and monocytes

4 Functions of WBCs Emigration of WBCs Usually live a few days Except for lymphocytes live for months or years Far less numerous than RBCs Leukocytosis is a normal protective response to invaders, strenuous exercise, anesthesia and surgery Leukopenia is never beneficial General function to combat invaders by phagocytosis or immune responses Many WBCs leave the bloodstream Emigration (formerly diapedesis) Roll along endothelium Stick to and then squeeze between endothelial cells Precise signals vary for different types of WBCs WBCs WBCs Neutrophils and macrophages are active phagocytes Attracted by chemotaxis Neutrophils respond most quickly to tissue damage by bacteria Uses lysozymes, strong oxidants, defensins Monocytes take longer to arrive but arrive in larger numbers and destroy more microbes Enlarge and differentiate into macrophages Basophila leave capillaries and release granules containing heparin, histamine and serotonin, at sites of inflammation Intensify inflammatory reaction Involved in hypersensitivity reactions (allergies) Eosinophils leave capillaries and enter tissue fluid Release histaminase, phagocytize antigenantibody complexes and effective against certain parasitic worms Lymphocytes Platelets/ Thrombocytes Lymphocytes are the major soldiers of the immune system B cells destroying bacteria and inactivating their toxins T cells attack viruses, fungi, transplanted cells, cancer cells and some bacteria Natural Killer (NK) cells attack a wide variety of infectious microbes and certain tumor cells Myeloid stem cells develop eventually into a megakaryocyte Splinters into fragments Each fragment enclosed in a piece of plasma membrane Disc-shaped with many vesicles but no nucleus Help stop blood loss by forming platelet plug Granules contain blood clot promoting chemicals Short life span 5-9 days 4

5 Stem cell transplants Hemostasis Bone marrow transplant Recipient's red bone marrow replaced entirely by healthy, noncancerous cells to establish normal blood cell counts Takes - weeks to begin producing enough WBCs to fight off infections Graft-versus-host-disease transplanted red bone marrow may produce T cells that attack host tissues Cord-blood transplant Stem cells obtained from umbilical cord shortly before birth Easily collected and can be stored indefinitely Less likely to cause graft-versus-host-disease Sequence of responses that stops bleeding mechanisms reduce blood loss. Vascular spasm Smooth muscle in artery or arteriole walls contracts. Platelet plug formation Platelets stick to parts of damaged blood vessel, become activated and accumulate large numbers. Blood clotting (coagulation) Platelet Plug Formation Red blood cell Platelet Collagen fibers and damaged endothelium Platelet adhesion Liberated ADP, serotonin, and thromboxane A Platelet release reaction Platelet plug Platelet aggregation Blood Clotting Stages of Clotting. Blood clotting Serum is blood plasma minus clotting proteins Clotting series of chemical reactions culminating in formation of fibrin threads Clotting (coagulation) factors Ca, several inactive enzymes, various molecules associated with platelets or released by damaged tissues. Extrinsic or intrinsic pathways lead to formation of prothrombinase. Prothrombinase converts prothrombin into thrombin. Thrombin converts fibrinogen (soluble) into fibrin (insoluble) forming the threads of the clot 5

6 (a) Extrinsic pathway Tissue trauma (b) Intrinsic pathway Blood trauma Damaged endothelial cells expose collagen fibers Blood Clotting Tissue factor (TF) Damaged platelets Activ ated XII Activ ated Ca Ca platelets Platelet phospholipids Activ ated X Activ ated X V V Ca Ca PROTHROMBINASE (c) Common pathway Ca Prothrombin (II) THROMBIN Ca XIII Fibrinogen (I) Activ ated XIII Loose fibrin STRENGTHENED threads FIBRIN THREADS Extrinsic pathway Fewer steps then intrinsic and occurs rapidly Tissue factor (TF) or thromboplastin leaks into the blood from cells outside (extrinsic to) blood vessels and initiates formation of prothrombinase Intrinsic pathway More complex and slower than extrinsic Activators are either in direct contact with blood or contained within (intrinsic to) the blood Outside tissue damage not needed Also forms prothrombinase Blood Clotting: Common pathway Blood Groups and Blood Types Marked by formation of prothrombinase Prothrombinase with Ca catalyzes conversion of prothrombin to thrombin Thrombin with Ca converts soluble fibrinogen into insoluble fibrin Thrombin has positive feedback effects Accelerates formation of prothrombinase Thrombin activates platelets Clot formation remains localized because fibrin absorbs thrombin and clotting factor concentrations are low Agglutinogens surface of RBCs contain genetically determined assortment of antigens Blood group based on presence or absence of various antigens At least 4 blood groups and more than 00 antigens ABO and Rh ABO Blood Group Based on A and B antigens Type A blood has only antigen A Type B blood has only antigen B Type AB blood has antigens A and B Universal recipients neither anti-a or anti-b antibodies Type O blood has neither antigen Universal donor Reason for antibodies presence not clear Antigens and Antibodies of ABO Blood Types 6

7 Hemolytic Disease Typing Blood Rh blood group People whose RBCs have the Rh antigen are Rh People who lack the Rh antigen are Rh - Normally, blood plasma does not contain anti-rh antibodies Hemolytic disease of the newborn (HDN) if blood from Rh fetus contacts Rh - mother during birth, anti-rh antibodies made Affect is on second Rh baby Single drops of blood are mixed with different antisera Agglutination with an antisera indicates the presence of that antigen on the RBC End of Chapter 9 Copyright 009 John Wiley & Sons, Inc. All rights reserved. Reproduction or translation of this work beyond that permitted in section 7 of the 976 United States Copyright Act without express permission of the copyright owner is unlawful. Request for further information should be addressed to the Permission Department, John Wiley & Sons, Inc. The purchaser may make back-up copies for his/her own use only and not for distribution or resale. The Publishers assumes no responsibility for errors, omissions, or damages caused by the use of theses programs or from the use of the information herein. 7