BLOOD CHAPTER 10

I. OVERVIEW

A. Components formed elements: living blood cells plasma: nonliving fluid matrix

Blood is the body’s only fluid tissue Composition of Blood Blood is the body’s only fluid tissue It is composed of liquid plasma and formed elements Formed elements include: Erythrocytes, or red blood cells (RBCs) Leukocytes, or white blood cells (WBCs) Platelets Hematocrit – the percentage of RBCs out of the total blood volume

Physical Characteristics and Volume Blood is a sticky, opaque fluid with a metallic taste Color varies from scarlet to dark red The pH of blood is 7.35–7.45 Temperature is 38C Blood accounts for approximately 8% of body weight Average volume: 5–6 L for males, and 4–5 L for females

B. Functions 1. distribution delivery of oxygen & nutrients transport waste transport hormones maintenance of body temperature

Functions 2. Body Protection prevention of blood loss prevention of infection

Functions 3. Regulation Appropriate body temperature by absorbing and distributing heat Normal pH in body tissues using buffer systems Adequate fluid volume in the circulatory system

II. FORMED ELEMENTS 1. Erythrocytes, leukocytes, and platelets make up the formed elements Only WBCs are complete cells RBCs have no nuclei or organelles, and platelets are just cell fragments 2. Most formed elements survive in the bloodstream for only a few days 3. Most blood cells do not divide but are renewed by cells in bone marrow

A. ERYTHROCYTES

1. Structural Characteristics also called Red Blood Cells (RBC’s) contains hemoglobin(main protein) which carries oxygen biconcave disks no nucleus

Erythrocytes (RBCs) Figure 17.3

Structural characteristics contribute to its gas transport function Erythrocytes (RBCs) Erythrocytes are an example of the complementarity of structure and function Structural characteristics contribute to its gas transport function Biconcave shape has a huge surface area relative to volume Erythrocytes are more than 97% hemoglobin ATP is generated anaerobically, so the erythrocytes do not consume the oxygen they transport

2. Erythrocyte Function RBCs are dedicated to respiratory gas transport Hb reversibly binds with oxygen and most oxygen in the blood is bound to Hb Hb is composed of the protein globin, made up of two alpha and two beta chains, each bound to a heme group Each heme group bears an atom of iron, which can bind to one oxygen molecule Each Hb molecule can transport four molecules of oxygen

Structure of Hemoglobin Figure 17.4

3. Production of RBC’s hematopoiesis: blood formation red bone marrow erythropoiesis: RBC formation 1. production by immature erythrocytes of substantial number of ribosomes

2. synthesis of hemoglobin at these ribosomes & its accumulation in cell’s cytoplasm 3. ejection of erythrocyte’s nucleus & most of its organelles

Production of Erythrocytes: Erythropoiesis Figure 17.5

4. Fate & Destruction of RBC’s no nucleus - cannot grow & divide life span 100 - 120 days become trapped & damaged in smaller circulatory channels engulfed by phagocytes iron recycled p. 575 figure 18.7

5. Erythrocyte Disorders Anemias: reduced oxygen-carrying ability of blood fatigued, pale, short of breath & chilly Iron-deficiency anemia: inadequate intake of iron-containing foods, impaired iron absorption, or chronic blood loss

Pernicious anemia: deficiency of vitamin B12 sickle-cell anemia: hemoglobin is spiky & sharp becomes crescent-shaped

B. LEUKOCYTES

1. STRUCTURES white blood cells (WBC’s) less numerous than RBC’s crucial to body defenses

2. Functional Characteristics form protective mobile army against bacteria, viruses, parasites, toxins, & tumor cells can slip into & out of blood vessels by diapedesis pinpoint areas of tissue damage & destroy foreign substances or dead cells two groups – Granulocytes and Agranulocytes

a. Granulocytes neutrophils: nuclei consist of 3-5 lobes attracted to sites of inflammation & active phagocytes basophils: u or s-shaped nucleus causes cells to release heparin & histamine histamine: vasodilator heparin: prevents blood clotting enhance migration of wbc’s

Neutrophil

Neutrophil

Basophil

Basophil

eosinophils: nucleus has two lobes like figure 8 reside in intestinal & pulmonary mucosae phagocytic

Eosinophil

b. Agranulocytes lymphocytes monocytes found in lymph tissue major cell of immunity nucleus is spherical & takes up most of cell monocytes nucleus is kidney shaped highly mobile phagocytic

lymphocyte

Lymphocyte

Monocyte

3. Production leukopoiesis: production of wbc’s produced in bone marrow life span from a few days to several years

Figure 17.11 Stem cells Hemocytoblast Myeloid stem cell Lymphoid stem cell Committed cells Myeloblast Myeloblast Myeloblast Lymphoblast Develop- mental pathway Promyelocyte Promyelocyte Promyelocyte Promonocyte Prolymphocyte Eosinophilic myelocyte Basophilic myelocyte Neutrophilic myelocyte Eosinophilic band cells Basophilic band cells Neutrophilic band cells Eosinophils Basophils Neutrophils Monocytes Lymphocytes (a) (b) (c) (d) (e) Some become Agranular leukocytes Granular leukocytes Some become Macrophages (tissues) Plasma cells Figure 17.11

4. Leukocyte Disorders leukemias: cancerous condition of wbc’s bone marrow becomes almost totally occupied by leukocytes rbc & platelet production is crowded out infectious mononucleosis: excessive monocytes & lymphocytes tired, achy, sore throat, low grade fever

C. THROMBOCYTES

platelets essential for blood clotting form temporary plug

Genesis of Platelets The stem cell for platelets is the hemocytoblast The sequential developmental pathway is as shown. Stem cell Developmental pathway Hemocytoblast Megakaryoblast Promegakaryocyte Megakaryocyte Platelets Figure 17.12

III. PLASMA

Blood plasma contains over 100 solutes, including: Proteins – albumin, globulins, clotting proteins, and others Lactic acid, urea, creatinine Organic nutrients – glucose, carbohydrates, amino acids Electrolytes – sodium, potassium, calcium, chloride, bicarbonate Respiratory gases – oxygen and carbon dioxide

IV. HEMOSTASIS

Stoppage of blood flow vascular spasms platelet plug formation coagulation or blood clotting http://adam.about.com/care/Blood-clotting-animation.htm http://www.mhhe.com/biosci/esp/2002_general/Esp/folder_structure/tr/m1/s7/trm1s7_3.htm

A. DISORDERS OF HEMOSTASIS

Thrombus: clot that develops & persists in an unbroken blood vessel if too large may block circulation Embolus: thrombus that breaks away from vessel wall & floats freely in bloodstream will block circulation if encounters small artery

Thrombocytopenia: condition in which number of circulating platelets is reduced, causes bleeding Hemophilias: inability for blood to clot properly

V. TRANSFUSION & BLOOD REPLACEMENT

A. ABO BLOOD GROUPS based on the presence or absence of two agglutinogens, type A and type B know table 10.3 p.319

B. Rh BLOOD GROUPS Rh positive: carry Rh antigens Rh negative during & after pregnancy a Rh- mother must receive RhoGAM if she has carried a Rh+ baby Why?

C. Transfusion Reactions oxygen carrying capacity of transfused blood cells is disrupted clumping of red blood cells in small vessels hinders blood flow to tissues beyond those points especially occurs in kidneys & causes kidney failure

Hemolytic Disease of the Newborn Hemolytic disease of the newborn – Rh+ antibodies of a sensitized Rh– mother cross the placenta and attack and destroy the RBCs of an Rh+ baby Rh– mother becomes sensitized when exposure to Rh+ blood causes her body to synthesize Rh+ antibodies

Hemolytic Disease of the Newborn The drug RhoGAM can prevent the Rh– mother from becoming sensitized Treatment of hemolytic disease of the newborn involves pre-birth transfusions and exchange transfusions after birth