Copyright 2003 by Mosby, Inc. All rights reserved.
CHAPTER 11
CIRCULATORY SYSTEM
Copyright 2003 by Mosby, Inc. All rights reserved.
Structure and Function
• Structure of the circulatory system– Includes the blood and lymph that
move through the body
• Function of the circulatory system– Both blood and lymph are tissues that
maintain homeostasis and give the body immunity
Copyright 2003 by Mosby, Inc. All rights reserved.
Blood
• Body contains approximately 4 to 5 liters of blood, making up about 8% of the body’s weight
• Functions include:– Transporting nutrients, oxygen, and hormones– Removing metabolic wastes and carbon
dioxide– Providing immunity through antibodies– Maintaining body temperature and electrolyte
balance– Clotting to prevent bleeding from a wound
Copyright 2003 by Mosby, Inc. All rights reserved.
Red Blood Cells (Erythrocytes)• Erythrocytes contain a protein called
hemoglobin that carries oxygen to all cells and removes carbon dioxide
• Each red blood cell lives only 90 to 120 days
• New cells are manufactured by the red marrow or myeloid tissue in bones
• The liver and spleen remove dead red blood cells
Copyright 2003 by Mosby, Inc. All rights reserved.
White Blood Cells (Leukocytes)• White blood cells remove foreign
particles, fight infection, and help prevent disease
• There are fewer white blood cells than red
• White blood cells are larger than red• Leukocytes live about 9 days• Pus consists of white blood cells mixed
with bacteria
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Five Types of White Blood Cells• Neutrophils• Basophils• Eosinophils• Lymphocytes• Monocytes
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Platelets (Thrombocytes)
• Smallest blood cells • Platelets promote clotting to
prevent blood loss• Platelets can form a plug to seal
small vessels by themselves or start the clotting process
• Produced in red bone marrow• Live about 5 to 9 days
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Plasma
• A pale yellow liquid that remains when elements are removed from blood
• Whole blood is 55% plasma• Plasma is 90% water and approximately
10% proteins• It contains nutrients, electrolytes,
oxygen, enzymes, hormones, and wastes
• Helps fight infection and assists in the clotting (coagulation) of blood
Copyright 2003 by Mosby, Inc. All rights reserved.
Blood Typing
• A person’s blood type is an inherited characteristic of the blood
• A blood type is determined by the antigens located on the surface of the red blood cell
• Clumping of incompatible cells blocks blood vessels and may cause death
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Table 11-2 Blood Types
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Lymph and Lymphatic Tissue• Two important functions
– The process of immunity – Maintaining the body’s fluid balance
• Lymph is a watery substance formed from fluid that filters into the body tissue or interstitially
• Lymphatic tissues consist of the tonsils, thymus, spleen, nodes, and the lymph vessels
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Immunity• Immune response takes on two forms
– As a barrier of the skin, mucous membranes, tears, and the leukocytes
– In leukocytes antibodies are formed in response to antigens or foreign materials that enter the body
• May be a localized or systemic reaction
• Acquired and/or inherited immunity
Copyright 2003 by Mosby, Inc. All rights reserved.
Assessment Techniques
• Hemoglobin (Hgb) test measures the amount of oxygen-carrying ability of the blood
• Hematocrit (Hct) measures the volume of erythrocytes in the blood
• Sedimentation rates measure how long it takes for erythrocytes in the blood to settle to the bottom of a container
• Reticulocyte studies measure the number of immature red blood cells
Copyright 2003 by Mosby, Inc. All rights reserved.
Assessment Techniques (continued)• Red blood cell (RBC) counts determine
the number of circulating red blood cells in 1 mm3 of blood
• Platelet or thrombocyte counts measure the number of platelets in 1 mm3 of blood to determine clotting ability
• Aspiration biopsy cytology (ABC) studies examine bone marrow from the iliac crest of the hip
Copyright 2003 by Mosby, Inc. All rights reserved.
Issues and Innovations• Transfusion
– Risks
– Autologous transfusions– Platelet donations
• Interferon– Prevention of viral diseases
• Monoclonal antibodies– Used in organ transplants, against autoimmune disease, and to diagnose certain diseases
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