3 12.1: Introduction Blood: Is connective tissue Transports vital substances Maintains stability of interstitial fluid Distributes heat Blood cells: Form mostly in red bone marrow and are: Red blood cells (RBCs) White blood cells (WBCs) Platelets (cell fragments) The amount of blood varies with body size, changes in fluid concentration, changes in electrolyte concentration, and amount of adipose tissue Blood is about 8% of body weight Adult blood volume is about 5 liters
10 Red Blood Cell Counts RBC counts is the number of RBCs in a cubic millimeter or microliter of blood It may vary depending on age and health Typical ranges include: 4,600,000 – 6,200,000 in males 4,200,000 – 5,400,000 in adult females 4,500,000 – 5,100,000 in children RBC counts reflects blood’s oxygen carrying capacity
12 Dietary Factors Affecting Red Blood Cell Production Vitamin B 12 and folic acid are necessary They are required for DNA synthesis making them necessary for the growth and division of all cells Iron is also necessary It is required for hemoglobin synthesis
16 Types of White Blood Cells White blood cells: Are leukocytes Protect against disease WBC hormones are interleukins and colony-stimulating factors which stimulate development There are five types of WBCs in two categories: Granulocytes Neutrophils Eosinophils Basophils Agranulocytes Lymphocytes Monocytes
24 White Blood Cell Counts A procedure used to count number of WBCs per cubic millimeter of blood Typically 5,000 – 10,000 per cubic millimeter of blood Leukopenia: Low WBC count (below 5,000) Typhoid fever, flu, measles, mumps, chicken pox, AIDS Leukocytosis: High WBC count (above 10,000) Acute infections, vigorous exercise, great loss of body fluids Differential WBC count Lists percentages of types of leukocytes May change in particular diseases
26 Blood Platelets Platelets are also known as thrombocytes They are cell fragments of megakaryocytes They lack a nucleus and are roughly half the size of a RBC There are approximately 130,000 – 360,000 per cubic millimeter of blood They help repair damaged blood vessels by sticking to broken surfaces
28 12.3: Blood Plasma Blood plasma is: Straw colored The liquid portion of blood 55% of blood volume 92% water Includes transporting nutrients, gases, and vitamins Helps regulate fluid and electrolyte balance and maintain pH
29 Plasma Proteins These are the most abundant dissolved substances (solutes) in plasma
30 Gases and Nutrients The most important blood gases: Oxygen Carbon dioxide Plasma nutrients include: Amino acids Simple sugars Nucleotides Lipids Fats (triglycerides) Phospholipids Cholesterol
31 Nonprotein Nitrogenous Substances These are molecules containing nitrogen but are not proteins In plasma they include: Urea – product of protein catabolism; about 50% of nonprotein nitrogenous substances Uric acid – product of nucleic acid catabolism Amino acids – product of protein catabolism Creatine – stores phosphates Creatinine – product of creatine metabolism BUN – blood urea nitrogen; indicates health of kidney
32 Plasma Electrolytes Plasma contains a variety of these ions called electrolytes They are absorbed from the intestine or released as by- products of cellular metabolism They include: Sodium (most abundant with chloride) Potassium Calcium Magnesium Chloride (most abundant with sodium) Bicarbonate Phosphate Sulfate
33 12.4: Hemostasis Hemostasis refers to the stoppage of bleeding Actions that limit or prevent blood loss include: Blood vessel spasm Platelet plug formation Blood coagulation
34 Blood Vessel Spasm Blood vessel spasm Triggered by pain receptors, platelet release, or serotonin Smooth muscle in blood vessel contracts
36 Blood Coagulation Blood coagulation Triggered by cellular damage and blood contact with foreign surfaces A blood clot forms This is a: Hemostatic mechanism Causes the formation of a blot clot via a series of reactions which activates the next in a cascade Occurs extrinsically or intrinsically
38 Extrinsic Clotting Mechanism Extrinsic clotting mechanism Chemical outside of blood vessel triggers blood coagulation Triggered by tissue thromboplastin (factor III) (not found in blood) A number of events occur that includes factor VII, factor X, factor V, factor IV, and factor II (prothrombin) Triggered when blood contacts damaged blood vessel walls or tissues This is an example of a positive feedback mechanism
40 Intrinsic Clotting Mechanism Intrinsic clotting mechanism Chemical inside blood triggers blood coagulation Triggered by Hageman factor XII (found inside blood) Factor XII activates factor XI which activates IX which joins with factor VIII to activate factor X Triggered when blood contacts a foreign surface
43 Fate of Blood Clots After a blood clot forms it retracts and pulls the edges of a broken blood vessel together while squeezing the fluid serum from the clot Platelet-derived growth factor stimulates smooth muscle cells and fibroblasts to repair damaged blood vessel walls Plasmin digests the blood clots A thrombus is an abnormal blood clot An embolus is a blood clot moving through the blood vessels
45 Prevention of Coagulation The smooth lining of blood vessels discourages the accumulation of platelets and clotting factors As a clot forms fibrin absorbs thrombin and prevents the clotting reaction from spreading Anti-thrombin inactivates additional thrombin by binding to it and blocking its action on fibrinogen Some cells such as basophils and mast cells secrete heparin (an anticoagulant)
47 12.5: Blood Groups and Transfusions In 1910, identification of the ABO blood antigen gene explained the observed blood type incompatibilities Today there are 31 different genes known to contribute to the surface features of RBCs determining compatibility between blood types
48 Antigens and Antibodies Terms to become familiar with: Agglutination – clumping of red blood cells in response to a reaction between an antibody and an antigen Antigens – a chemical that stimulates cells to produce antibodies Antibodies – a protein that reacts against a specific antigen
53 Rh Blood Group The Rh blood group was named for the rhesus monkey The group includes several Rh antigens or factors Rh positive – presence of antigen D or other Rh antigens on the red blood cell membranes Rh negative – lack of these antigens The seriousness of the Rh blood group is evident in a fetus that develops the condition erythroblastosis fetalis or hemolytic disease of the newborn
55 Important Points in Chapter 12: Outcomes to be Assessed 12.1: Introduction Describe the general characteristics of blood and discuss its major functions. Distinguish among the formed elements of blood and the liquid portion of blood. 12.2: Blood Cells Describe the origin of blood cells. Explain the significance of red blood cells counts and how they are used to diagnose disease. Discuss the life cycle of a red blood cell. Summarize the control of red blood cell production.
56 Important Points in Chapter 12: Outcomes to be Assessed Distinguish among the five types of white blood cells and give the function(s) of each type. Describe a blood platelet and explain its functions. 12.3: Blood Plasma Describe the functions of each of the major components of plasma. 12.4: Hemostasis Define hemostasis and explain the mechanisms that help to achieve it. Review the major steps in coagulation. Explain how to prevent coagulation.
57 Important Points in Chapter 12: Outcomes to be Assessed 12.5: Blood Groups and Transfusions Explain blood typing and how it is used to avoid adverse reactions following blood transfusions. Describe how blood reactions may occur between fetal and maternal tissues.