11 circulatory system

Copyright 2003 by Mosby, Inc. All rights reserved.

CHAPTER 11

CIRCULATORY SYSTEM


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


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


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


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


Five Types of White Blood Cells• Neutrophils• Basophils• Eosinophils• Lymphocytes• Monocytes


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


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


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


Table 11-2 Blood Types


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


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


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


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


Disorders of the Circulatory System • Acquired immunodeficiency syndrome

– Dysfunction of the immune system caused by a virus

• Allergy– Hypersensitive response by the immune

system to an outside substance

• Anemia– The blood has an inadequate amount of

hemoglobin, red blood cells, or both


Disorders of the Circulatory System (continued)

• Autoimmune– Conditions in which the immune system of

the body turns against itself

• Elephantiasis– A massive accumulation of lymphatic fluid in

body tissues, causing an abnormally large growth of tissue or hypertrophy

• Erythroblastosis fetalis – A condition in an unborn baby in which the

mother forms antibodies against the antigens in the baby’s blood



• Hemophilia – A rare sex-linked genetic blood disease in

which the blood is missing a clotting factor • Hepatitis

– A viral infection of the blood

• Hodgkin’s disease – A malignant cancer of the lymph system



• Leukemia – Also called blood cancer, is an abnormal

malignant increase in the number and longevity of white blood cells

• Lymphosarcoma – Is a group of malignant cancers of lymph

tissues other than Hodgkin's disease

• Polycythemia – An abnormal increase in the number of blood

cells, making the blood thicker and slower flowing



• Septicemia – Called blood poisoning, is an infection that

occurs when pathogens enter the blood

• Sickle cell anemia – A genetic condition that results in malformed

red blood cells • Splenomegaly

– An enlargement of the spleen caused by an acute infection such as mononucleosis or anemia



• Thalassemia – One of the most common genetic blood

disorders

• Thrombocytopenia – A decrease in the number of platelets in the

blood

• Thrombosis – A condition in which a blood clot, called a

thrombus, forms in the blood vessels


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

11 circulatory system

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