CHAPTER 10 BLOOD

Introduction Blood is the RIVER OF LIFE that surges within us. It transports everything that must be carried from one place to another within the body – nutrients, wastes, and body heat – through blood vessels.

Components of Blood Blood = a complex connective tissue in which living blood cells, the formed elements, are suspended in plasma Breakdown of Blood Plasma = 55% Formed Elements = 45% - this % is known as the hematocrit

Physical Characteristics and Volume of Blood Appearance = a sticky fluid with a metallic taste Color = varies from scarlet red to a dull red Weight = thicker and heavier than water pH = 7.4 Volume = 8% of body weight (6 quarts)

Plasma Plasma – the liquid part of blood and is approximately 90% water Functions: Transport various substances around the body Helps distribute body heat evenly throughout the body

Formed Elements (Cells): Erythrocytes – red blood cells 4 to 6 million found in the body Lack a nucleus and some organelles Carry oxygen in blood to all cells of the body Contain hemoglobin – transports the oxygen that is carried in the blood

Formed Elements (Cells): Leukocytes – white blood cells 4 to 11 thousand found in the body Contain a nucleus and all organelles Used in body immunity and defense

2 major groups of WBCs: Granulocytes: Neutrophils = act rapidly at sites of infection Eosinophils = act rapidly during allergies Basophils = contains histamine which helps during inflammation Agranulocytes Lymphocytes = found in lymphatic tissue and play a role in immunity Monocytes = help fight chronic infections

Platelets Fragments of cells that are needed for normal blood clotting

Hematopoiesis Blood cell formation which occurs in red bone marrow

Hemostasis Definition – stoppage of blood flow Three major phases: Platelet plug formation – Platelets build up and cling to a damaged site to form a plug Vascular spasms – The platelets release serotonin which causes the blood vessel to go into spasms. The spasms decrease blood loss until clotting can occur. Coagulation – The blood begins to clot until a mass forms and it pulls the blood vessels closer together.

Human Blood Groups Antigens – substances that the body recognizes as foreign; could be a virus or bacteria but also could be blood from a blood transfusion Antibodies – defend against antigens If antigens are present on the RBC, antibodies will bind to the RBCs and cause the RBCs to clump together = Agglutination. This could lead to the clogging of small blood vessels throughout the body and thus causing more problems throughout the body.

ABO Blood Grouping Based on 2 antigens = type A or type B Absence of both antigens = type O (UNIVERSAL DONOR) Presence of both antigens = type AB (UNIVERSAL RECIPIENT)

Blood Typing It is very important to determine the blood group of both the donor and the recipient BEFORE blood is transfused.

Developmental Aspects of Blood Development of the entire circulatory system occurs very early in the young embryo. The elderly are at risk for anemia and clotting disorders. Leukemias are most common in the very young and very old.

Disorders Anemia = a decrease in the oxygen-carrying ability of the blood Sickle-Cell Anemia = The abnormal hemoglobin becomes spiky and sharp when the oxygen content of the blood is lower than normal. The deformed cells rupture easily and block small blood vessels which interfere with oxygen delivery. It occurs mainly in African Americans.

Disorders Leukemia = The bone marrow becomes cancerous and WBCs are formed rapidly. The newly formed WBCs are immature and unable to carry out their normal functions. Hemophilia = A bleeding disorder that results from a lack of blood clotting