What is the composition of blood, including blood cells? What organs and structures control the flow of blood throughout the body?

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1 3 Chapter 10: Circulatory System and Lymphatic System In this chapter, you will learn about the structure and function of the circulatory system and lymphatic system. What is the composition of blood, including blood cells? What organs and structures control the flow of blood throughout the body? Blood: is a liquid connective tissue that has many different functions. Transports nutrients, wastes, and hormones Regulates body temperature by dispersing body heat Regulates blood pressure (plasma proteins contribute to osmotic pressure of blood) Protects the body against invasion by disease-causing pathogens Clotting mechanisms protect the body against loss of blood. 5 Composition of Blood: Blood separates into three layers when centrifuged McGraw Hill Upper layer: plasma (liquid portion of blood) Lower layers: formed elements (white blood cells, platelets, red blood cells) 6 Plasma Plasma contains a variety of inorganic and organic substances dissolved or suspended in water.

2 7. Plasma also contains plasma proteins, which have many functions: Transport: albumin transports bilirubin; lipoproteins transport cholesterol Blood clotting: fibrinogen Fighting infection: antibodies Maintaining blood volume: plasma proteins are too large to leave the capillaries Blood in capillaries has a higher solute concentrate than tissue fluid, causing water to diffuse in 8 The Red Blood Cells Red blood cells (erythrocytes) are manufactured in the red bone marrow of the skull, ribs, vertebrae, and ends of the long bones. They transport oxygen and carbon dioxide in the blood. 9 Mature red blood cells have no nuclei and are biconcave. Only live about 120 days (possibly due to lack of nuclei) and are destroyed in the liver and spleen Biconcave shape increases flexibility (for moving through capillary beds) and surface area (for diffusion of gases) Contain hemoglobin, a respiratory pigment that carries oxygen o Iron in hemoglobin acquires oxygen in the lungs and gives it up in the tissues

3 10.4 McGraw Hill 11. Anemia is a common blood disorder that results in a tired, rundown feeling. Anemia has three basic causes: Decreased production of red blood cells Loss of red blood cells from the body Destruction of red blood cells within the body Most common type of anemia is iron-deficiency anemia Caused by decreased production of red blood cells due to a diet that lacks adequate iron 12 The White Blood Cells White blood cells (leukocytes) are usually larger than red blood cells, have a nucleus, lack hemoglobin, and appear translucent without staining. They fight infection and play a role in developing immunity. Fig White blood cells can be divided on the basis of structure into granular leukocytes and agranular leukocytes: Granular leukocytes: neutrophils, eosinophils, basophils Agranular leukocytes: monocytes, lymphocytes

4 15 Granular leukocytes are filled with spheres that contain enzymes and proteins that help white blood cells defend against microbes. Neutrophils: phagocytize pathogens Eosinophils: phagocytize antigen-antibody complexes and allergens Basophils: release histamine to promote blood flow to injured tissues 16. Agranular leukocytes: include cells that can phagocytize pathogens and cells that are involved in specific immunity Monocytes: largest white blood cells; differentiate into phagocytic dendritic cells and macrophages Lymphocytes: o B lymphocytes (B cells): produce antibodies o T lymphocytes (T cells): helper T cells regulate the responses of other cells; cytotoxic T cells kill other cells White Blood Cells and Disease The number of white blood cells increases or decreases beyond normal if disease is present. Neutrophils: increase in response to bacterial infections B cells: increase in response to infectious mononucleosis T cells: a low number of T cells indicates if an HIV-infected person has AIDS

5 A large number of abnormal white blood cells is a characteristic of leukemia, a form of cancer 10.6 McGraw Hill Macrophage engulfing bacteria 19 The Platelets and Blood Clotting Platelets (also called thrombocytes) result from fragmentation of large cells called megakaryocytes in the red bone marrow. Platelets are involved in blood clotting (coagulation). There are at least 12 clotting factors in the blood that help platelets in the formation of a blood clot (examples: prothrombin, fibrinogen). 20 Blood Clotting The process of clotting begins when a blood vessel is damaged. 1. Platelets clump at the site of damage and form a plug to partially seal the leak. 2. Platelets and damaged tissue release prothombin activator, which converts prothrombin (a clotting factor) to thrombin in the presence of calcium ions. 21

6 3. Thrombin acts as an enzyme on fibrinogen (a clotting factor) to form fibrin threads Fibrin threads wind around the platelet plug and trap red blood cells to form the framework of the clot. Fig 10.7 McGraw-Hill 5. When blood vessel repair is initiated, plasmin (an enzyme) destroys the fibrin framework and restores the fluidity of the plasma. 23 Blood Clotting If blood is allowed to clot in a test tube, a yellowish material, called serum, develops above the clotted material 25 Hemophilia: A Blood Clotting Disorder Hemophilia is a group of inherited clotting disorders caused by a deficiency in a clotting factor Hemophilia A: 90% of all hemophilia cases Occurs frequently in males since the faulty gene is on the X chromosome Individuals with hemophilia are more prone to bleeding Bleeding in the muscles can lead to nerve damage Bleeding into the brain can lead to neurological damage or death Individuals require frequent blood transfusions or injections of the deficient clotting factor 26 Bone Marrow Stem Cells A stem cell is a cell that is ever capable of dividing and producing new cells that go on to differentiate into particular types of cells.

7 10.8 McGraw Hill 28 Multipotent stem cells in red bone marrow have the potential to give rise to other stem cells for the various formed elements. Can also differentiate into other cells (liver, bone, fat, cartilage, heart, neurons) A patient s own bone marrow stem cells (adult stem cells) could be used to treat diabetes, heart disease, liver disease, or brain disorders Some researchers prefer using embryonic stem cells since they may be more likely to become any type of cell *Can be collected from unused embryos in fertility clinics, or umbilical cord blood 29 Capillary Exchange Fluid in the blood is called plasma. When blood reaches a capillary, the movement of fluid in the blood through the capillary wall is controlled by:

8 Osmotic pressure (causes water to move from the tissue fluid to the blood) Blood pressure (causes water to move from blood to tissue fluid) 10.9 McGraw-Hill 31 Arterial End of Capillary Blood pressure is higher than osmotic pressure of blood Water exits capillary Midway Along the Capillary Blood pressure and osmotic pressure cancel each other out No net movement of water Solutes diffuse according to concentration gradient o Nutrients and oxygen diffuse out of the capillary; wastes and carbon dioxide diffuse into the capillaries Small substances leaving capillaries contribute to tissue fluid 32 Venous End of Capillary Osmotic pressure is greater than blood pressure Water moves into capillary Excess tissue fluid is collected by lymphatic capillaries, where it becomes lymph McGraw-Hill

9 33 Check Your Progress 1. List the major components of blood, along with their functions. 2. Describe the cellular and molecular events that lead to blood clotting. 3. Identify some diseases that may be treatable with stem cell

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