1 Dr Stefany Diaz Anatomy 2 Blood Chapter

1 Dr. Stefany Diaz Anatomy 2 Blood Chapter 27

2 Blood is made up of plasma and formed elements Structure and Function of Blood It is a complex transport medium that performs vital pickup and delivery services for the body It also is the key component of the body’s heat-regulating mechanism

3 Composition of Whole Blood

4 § The hematocrit is also known as the Hematocrit packed cell volume § The term packed cell volume describes the volume percent of RBCs in whole blood § Normal whole blood is about 55% plasma and 45% RBCs (i. e. , the hematocrit is 45%)

5 Hematocrit Test

6 § Liquid part of blood; clear, straw-colored fluid made up of 90% water and 10% solutes § Solutes: 6% to 8% are proteins, consisting Blood Plasma of three main compounds: § Albumins: Help maintain osmotic balance of the blood § Globulins: Essential component of the immunity mechanism § Fibrinogen: Key role in blood clotting

7 Differences in Plasma and Serum

8 § RBCs have no nucleus and are shaped like biconcave disks Structure of Red Blood Cells § They do not contain ribosomes, mitochondria, or other organelles typical of most body cells § Primary component is hemoglobin (Hb) § Hb accounts for more than one third of the cell volume

9 Erythrocytes From Shiland BJ: Mastering Healthcare Terminology, ed. 3, St. Louis, 2010, Mosby.

10 § Critical role in the transport of oxygen and Function of Red Blood Cells carbon dioxide; depends on hemoglobin § Carbonic anhydrase: Enzyme in RBCs; catalyzes a reaction that joins carbon dioxide and water to form carbonic acid § Carbonic acid: Dissociates and generates bicarbonate ions, which diffuse out of the RBC and transport carbon dioxide in the blood plasma

11 Hemoglobin Inside each RBC are approximately 200 million to 300 million molecules of hemoglobin Hemoglobin is made up of four globin chains, with each attached to a heme group Hemoglobin is able to unite with four oxygen molecules to form oxyhemoglobin; this allows RBCs to transport oxygen where it is needed

12 Patton KT, Thibodeau G: Human Body in Health & Disease, ed. 6, St. Louis, 2014, Mosby. Structure of Hemoglobin

13 § Erythropoiesis: Entire process of RBC formation Formation of Red Blood Cells § RBC formation begins in the red bone marrow with hematopoietic stem cells (HSCs), which go through several stages of development to become erythrocytes § The entire maturation process requires approximately 4 days

14 Erythropoiesis

15 § Life span of a circulating RBC averages 105 to 120 days Life Cycle of Red Blood Cells § Macrophages phagocytose aged, abnormal, or fragmented RBCs § Hemoglobin is broken down, and amino acids, iron, and bilirubin are released

16 Red Blood Cell Life Cycle From Carr J, Rodak B: Clinical hematology atlas, St Louis, 1999, Elsevier.

17 § The term blood type refers to the type of cell markers or antigens present on RBC membranes § The presence or absence of blood Blood Types antigens A and B determines a person’s blood type in the ABO system § Additional antigens exist that are not as important clinically but still may cause occasional problems § During a blood transfusion, care must be taken to prevent a transfusion reaction

18 § Every person’s blood belongs to one of four ABO blood groups § The groups are named according to antigens present on RBC membranes ABO System § Type A: Antigen A is present on RBCs § Type B: Antigen B is present on RBCs § Type AB: Both antigen A and antigen B are present on RBCs § Type O: Neither antigen A nor antigen B is present on RBCs

19 ABO Blood Types

20 § Rh-positive blood: Rh antigen is present Rh System on the RBCs § Rh-negative blood: RBCs have no Rh antigen

21 Erythroblastosis Fetalis

22 Erythroblastosis Fetalis (Cont. )

23 § White blood cells (WBCs), or leukocytes, White Blood Cells do not contain pigments but appear white when collected together (like snowflakes) § Five different types have been classified according to their staining characteristics

24 § Neutrophils make up approximately 65% of the total WBC count in a normal blood sample Granulocytes § Highly mobile and very active phagocytic cells § Capable of diapedesis § Cytoplasmic granules contain lysosomes

25 Neutrophil Dennis Strete

26 § Eosinophils: Account for 2% to 5% of Granulocytes circulating WBCs; numerous in mucous lining of respiratory and digestive tracts; weak phagocytes; release chemicals of immunity; provide protection against infections caused by parasitic worms and help regulate allergic reactions § Basophils: Account for only 0. 5% to 1% of circulating WBCs; motile and capable of diapedesis; cytoplasmic granules contain histamine and heparin

27 Eosinophils Dennis Strete

28 Basophils Dennis Strete

29 § Lymphocytes: Smallest of the WBCs; second most numerous WBC; account for approximately 25% of circulating WBCs, play a huge part in infectious deseases. § T lymphocytes and B lymphocytes play Agranulocytes important roles in immunity: § T lymphocytes directly attack an infected or a cancerous cell § B lymphocytes produce antibodies against specific antigens § Monocytes: Largest leukocytes; mobile and highly phagocytic cells

30 Lymphocytes Dennis Strete

31 Monocytes Dennis Strete

32 § 1 mm 3 of normal blood usually contains White Blood Cell Numbers 5000 to 9000 leukocytes, with different percentages for each type § WBC numbers are clinically significant because they change with certain abnormal conditions

33 § Leukocytes and platelets, like erythrocytes, mature from the undifferentiated hematopoietic stem cell Formation of White Blood Cells § Two lines of blood stem cells emerge early in the process of leukopoiesis § The myeloid line, or “marrow line, ” produces the granular leukocytes and the monocytes § The lymphoid stem cell line produces only lymphocytes

34 § In circulating blood, platelets are small, Structure and Function of Platelets pale bodies that appear as irregular spindles or oval disks § Platelets have three important physical properties: Agglutination, adhesiveness, and aggregation § They play an important role in hemostasis

35 § The formation of platelets is called thrombopoiesis § Begins with the stimulation of precursor cells called megakaryoblasts Formation and Life Span of Platelets § Controlled by the hormone thrombopoietin § Mature megakaryocytes are primarily found in the red bone marrow, although some are located in the lungs and the spleen § Platelets have an average life span of about 7 days

36 From Carr JH, Rodak BF: Clinical Hematology Atlas, ed. 2, St. Louis, 2004, Elsevier. Megakaryocytes

37 § Vasoconstriction causes temporary closure of a damaged vessel and lessens blood loss § Platelet plug formation § 1 to 5 seconds after injury to a vessel wall, Hemostasis platelets adhere to damaged endothelial lining and to each other to form a platelet plug § A temporary platelet plug is an important step in hemostasis § “Sticky platelets” form the physical plug and secrete several chemicals involved in the coagulation process

38 § Involves a series of chemical reactions Blood Clotting (Coagulation) that take place quickly in a certain sequence to result in a net of fibers that traps RBCs § Three stages of coagulation: § Stage 1: Activation pathways: Intrinsic and extrinsic § Stage 2: Thrombin formation § Stage 3: Fibrin clot formation

39 Clot Formation

40 § Clot formation in intact vessels is opposed § Several factors oppose clotting: Conditions that Oppose Clotting § Most important: The perfectly smooth surface of the normal endothelial lining of blood vessels does not allow platelets to adhere § Antithrombins: Substances in the blood that oppose or inactivate thrombin

41 Conditions that Hasten Clotting § Rough spot in the endothelium § Abnormally slow blood flow § Once started, clots tend to grow

42 § Fibrinolysis: Physiological mechanism that dissolves clots § Plasmin: Enzyme in the blood that Clot Dissolution catalyzes the hydrolysis of fibrin, causing it to dissolve § Plasmin is activated by chemicals released from damaged cells and acts slowly to dissolve the clot

43 Fibrinolysis

44 § Basic mechanism is improper blood cell formation § Red blood cell disorders § Anemia: Several types Blood Disorders § White blood cell disorders § Lymphoid neoplasms § Multiple myeloma § Leukemia § Clotting disorders: Embolus, embolism, hemophilia, thrombocytopenia

45 Questions?