Blood List the components of the cardiovascular system and explain the major functions of this system. Describe the components and major functions of the blood List the characteristics and functions of red blood cells. Describe the structure of hemoglobin and indicate its functions. Discuss red blood cell production and maturation. Explain the importance of blood typing and the basis for ABO and Rh incompatibilities. Categorize the various white blood cells on the basis of structure and function. Describe the structure, function and production of platelets. Describe the reaction sequences responsible for blood clotting.

SECTION 19-1: The cardiovascular system Structures Heart Blood Vessels Blood Function Provides a mechanism for rapid transport of nutrients, waste products, respiratory gases and cells

SECTION 19-2: Functions & Composition of Blood Fluid connective tissue Functions include Transporting dissolved gases, nutrients, hormones, and metabolic wastes Regulating pH and ion composition of interstitial fluids Restricting fluid loss at injury sites Defending the body against toxins and pathogens Regulating body temperature by absorbing and redistributing heat

The composition of blood Plasma and formed elements comprise whole blood Red blood cells (RBC) White blood cells (WBC) Platelets Can fractionate whole blood for analytical or clinical purposes

Figure 19.1 The Composition of Whole Blood Figure 19.1b

Figure 19.1 The Composition of Whole Blood Figure 19.1c

Hemopoiesis Process of blood cell formation Hemocytoblasts are circulating stem cells that divide to form all types of blood cells Whole blood from anywhere in the body has roughly the same temperature, pH and viscosity

SECTION 19-3: Plasma Accounts for 46-63% of blood volume 92% of plasma is water Higher concentration of dissolved oxygen and dissolved proteins than interstitial fluid

Plasma proteins more than 90% are synthesized in the liver Albumins: 60% of plasma proteins Responsible for viscosity and osmotic pressure of blood Globulins: ~35% of plasma proteins Include immunoglobins which attack foreign proteins and pathogens Include transport globulins which bind ions, hormones and other compounds Fibrinogen Converted to fibrin during clotting Removal of fibrinogen leaves serum

SECTION 19-4: Red Blood Cells Erythrocytes account for slightly less than half the blood volume, and 99.9% of the formed elements Hematocrit measures the percentage of whole blood occupied by formed elements Commonly referred to as the volume of packed red cells

Structure of RBCs Biconcave disc, providing a large surface to volume ration Shape allows RBCs to stack, bend and flex RBCs lack organelles Typically degenerate in about 120 days.

Figure 19.2 The Anatomy of Red Blood Cells

Hemoglobin Molecules of hemoglobin account for 95% of the proteins in RBCs Hemoglobin is a globular protein, formed from two pairs of polypeptide subunits Each subunit contains a molecule of heme which reversibly binds an oxygen molecule Damaged or dead RBCs are recycled by phagocytes

RBC life span and circulation Replaced at a rate of approximately 3 million new blood cells entering the circulation per second. Replaced before they hemolyze Components of hemoglobin individually recycled Heme stripped of iron and converted to biliverdin, then bilirubin Iron is recycled by being stored in phagocytes, or transported throughout the blood stream bound to transferrin

Figure 19.5 Red Blood Cell Turnover

RBC Production Erythropoeisis = the formation of new red blood cells Occurs in red bone marrow Process speeds up with in the presence of EPO (Erythropoeisis stimulating hormone) RBCs pass through reticulocyte and erythroblast stages

Figure 19.6 Stages of RBC Maturation

Blood types Determined by the presence or absence of surface antigens (agglutinogens) Antigens A, B and Rh (D) Antibodies in the plasma (agglutinins) Cross-reactions occur when antigens meet antibodies

Figure 19.8 Blood Typing and Cross-Reactions

Figure 19.9 Blood Type Testing

SECTION 19-5: The White Blood Cells Called leukocytes Have nuclei and other organelles Defend the body against pathogens Remove toxins, wastes, and abnormal or damaged cells Are capable of amoeboid movement (margination) and positive chemotaxis Some are capable of phagocytosis

Types of WBC Granular leukocytes Neutrophils – 50 to 70 % total WBC population Eosinophils – phagocytes attracted to foreign compounds that have reacted with antibodies Basophils – migrate to damaged tissue and release histamine and heparin Agranular leukocytes Monocytes - become macrophage Lymphocytes – includes T cells, B cells, and NK cells

Figure 19.11 White Blood Cells

WBC Production Granulocytes and monocytes are produced by bone marrow stem cells Divide to create progenitor cells Stem cells may originate in bone marrow and migrate to peripheral tissues Several colony stimulating factors are involved in regulation and control of production

Figure 19.12 The Origins and Differentiation of Formed Elements PLAY Animation: The origins and differentiation of blood cells Figure 19.12

SECTION 19-6: Platelets Structure Flattened discs Circulate for 9-12 days before being removed by phagocytes Function Transporting chemicals important to clotting Forming temporary patch in walls of damaged blood vessels Contracting after a clot has formed

Platelet production (thrombocytopoiesis) Megakaryocytes release platelets into circulating blood Rate of platelet formation is stimulated by thrombopoietin, thrombocyte-stimulating factor, interleukin-6, and Multi-CSF

SECTION 19-7: Hemostasis Prevents the loss of blood through vessel walls Three phases – Vascular phase Local blood vessel constriction (vascular spasm) Platelet phase Platelets are activated, aggregate at the site, adhere to the damaged surfaces Coagulation phase

Figure 19.13 The Vascular and Platelet Phases of Hemostasis

Hemostasis: Coagulation phase Factors released by platelets and endothelial cells interact with clotting factors to form a clot Extrinsic pathway Intrinsic pathway Common pathway Suspended fibrinogen is converted to large insoluble fibrin fibers

Figure 19.14 The Coagulation Phase of Hemostasis Figure 19.14a

Figure 19.14 The Coagulation Phase of Hemostasis Figure 19.14b

Clot retraction Final phase of healing Platelets contract and pull the edges of the vessel together

Fibrinolysis Clot gradually dissolves through action of plasmin Activated form of plasminogen Clotting can be prevented through the use of drugs that depress the clotting response or dissolve existing clots Anticoagulants include heparin, coumadin, aspirin, dicumarol, t- PA, streptokinase, and urokinase

You should now be familiar with: The components of the cardiovascular system and its major functions. The important components and major functions of the blood. The characteristics and functions of red blood cells. The structure of hemoglobin and its functions. Red blood cell production and maturation. The importance of blood typing and the basis for ABO and Rh incompatibilities. The various white blood cells. The structure, function and production of platelets. The reaction sequences responsible for blood clotting.