BLOOD Blood is a Liquid Connective Tissue that

BLOOD Blood is a Liquid Connective Tissue that constitutes the transport medium of the circulatory system. The Two main functions of blood are to transport nutrients and oxygen to the cells and carry carbon dioxide and waste materials away from the cells. Blood also transfers heat to the body surface and plays a role in defending the body against disease.

• OBJECTIVES: List the components of blood. Distinguish between red blood cells, white blood cells, and platelets in terms of structure and function. Summarize the process of blood clotting. Explain what determine the compatibility of blood types for transfusion.

• 1. The Main Function of the Circulatory System is to Transport Material in a FLUID Medium throughout the body. • 2. THIS FLUID MEDIUM IS CALLED BLOOD IS A TYPE OF LIQUID CONNECTIVE TISSUE THAT HAS MANY FUNCTIONS. Blood is composed of a Liquid Medium and Blood Solids. The liquid makes up about 55 percent of the blood, and blood solids make up the remaining 45 percent. • 3. BLOOD TRANSPORT NUTRIENTS, DISSOLVED GASES (O 2, CO 2), ENZYMES, HORMONES, AND WASTE PRODUCTS. • 4. BLOOD REGULATES BODY TEMPERATURE, p. H, and ELECTROLYTES. • 5. BLOOD PROTECTS THE BODY FROM INVADERS, AND BLOOD RESTRICTS THE LOSS OF FLUID. • 6. Our Bodies contains 4 to 5 liters of Blood.

BLOOD PLASMA • 1. Approximately 55 percent of Blood in made up of a Fluid Portion called PLASMA. • 2. Plasma is the Straw-Colored Liquid portion of Blood and is 90 Percent Water and 10 percent dissolved fats, salts, sugars, and Proteins called PLASMA PROTEINS.

THE PLASMA PROTEINS ARE DIVIDED INTO THREE TYPES: A. ALBUMINS - HELP REGULATE OSMOTIC PRESSURE (MAINTAIN NORMAL BLOOD VOLUME AND BLOOD PRESSURE). THIS IS THE MOST ABUNDANT PLASMA PROTEIN. • B. GLOBULINS OR ANTIBODIES - INCLUDE ANTIBODIES THAT HELP FIGHT OFF INFECTION. ANTIBODIES INITIATE THE DESTRUCTION OF PATHOGENS AND PROVIDE US WITH IMMUNITY. • C. FIBRINOGEN - RESPONSIBLE FOR THE ABILITY OF BLOOD TO CLOT. •

BLOOD CELLS OR SOLIDS • THE CELLULAR PORTION OF BLOOD MAKE UP THE OTHER 45 PERCENT AND INCLUDES SEVERAL TYPES OF HIGHLY SPECIALIZED CELLS AND CELL FRAGMENTS. THEY ARE RED BLOOD CELLS (RBC), WHITE BLOOD CELLS (WBC), AND PLATELETS.

RED BLOOD CELLS (RBC) ERYTHROCYTES • 1. RBC are the most numerous of the Blood Cells. One microliter of blood contains approx. 5 million RBCs. (Figure 47 -11) • 2. RBC are BICONCAVE, or shaped so that they are narrower in the center than along the edges. • 3. RBC are produced from cells in the Bone Marrow, they are gradually filled with HEMOGLOBIN which forces out the nucleus and other organelles.

• 4. Mature RBC do not have a Cell Nucleus and Organelles. The Mature RBC becomes little more than a membrane sac containing Hemoglobin. • 5. Hemoglobin is the iron-containing protein that gives RBC the ability to carry Oxygen. Hemoglobin gives the RBC their color. • 6. RBC stay in circulation for about 120 days before they are destroyed by special WBC in the liver and spleen. RBC in your body are dying and being replace at a rate of about 2 million per second.

WHITE BLOOD CELLS (WBC) LEUKOCYTES • 1. Outnumbered by RBC almost 500 to 1. • 2. WBC are produced in the Red Bone Marrow, The Lymph Nodes, and the Spleen. They are larger than RBC, almost Colorless, and do NOT Contain Hemoglobin. (Figure 47 -12) • 3. WBC have a Nucleus and can live for many months or years.

• 4. THE MAIN FUNCTION OF WBC IS TO PROTECT THE BODY AGAINST INVASION BY FOREIGN CELLS OR SUBSTANCES. • 5. WBC called PHAGOCYTES can destroy bacteria and foreign cells by Phagocytosis (engulfed and digested), some produce special proteins called ANTIBODIES, and some release special chemicals that help the body fight off disease and resist infection. • 6. Doctors are able to detect the presence of infection by counting the number of WBC in the blood. When a person has an infection, the number of WBC can Double.

PLATELETS AND BLOOD CLOTTING • 1. Platelets are NOT Cells; they are tiny Fragments of other Cells that were formed in the bone marrow. • 2. Platelets are formed when small pieces of Cytoplasm are pinched off the large cells in the Red Bone Marrow called MEGAKARYOCYTES, which are found in the Bone Marrow. Platelets lack a nucleus and their life span is about 7 to 11 days. • 3. Platelets play an important role in Blood Clotting. • 4. Platelets help the Clotting process by Clumping together and forming a Plug at the site of a wound and then releasing proteins called CLOTTING FACTORS.

• 5. Clotting Factors start a series of Chemical Reactions that ends with a sticky meshwork of Fibrin Filaments that stop bleeding by producing a clot. (Figure 47 -14) • 6. A genetic disorder of Clotting Factors is called HEMOPHILIA, suffers may bleed uncontrollably from even a small cut or scrape. • 7. Clotting of blood in Vessels can block the flow of blood, if this happens in the brain, brain cells may die, causing a STROKE.