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Blood
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Lecture Outline
The Composition and Functions of Blood
o Functions of Blood• Transport
Carries oxygen to tissues Carries carbon dioxide and other wastes away
from tissues Hormones
• Defense Defends body against pathogens Removes dead and dying cells
• Regulation Body temperature Water-salt balance Body pH
Components of Blood
o Plasma• Liquid portion of blood• About 92% is water• About 8% is composed various salts
and organic molecules• Plasma proteins
Albumins Globulins
Alpha and beta – produced by the liver Gamma - antibodies
Fibrinogen – functions in blood clotting Help maintain homeostasis
Formed Elements
o Produced continuously in the red bone marrow of the:
• Skull• Ribs• Vertebrae• Iliac crests• Ends of long bones
Formed Elements
o Hematopoiesis• Multipotent stem cells – red bone
marrow cells• Multipotent cells replicate• Each daughter cell then differentiates
Myeloid stem cells further differentiates Red blood cells Granular leukocytes Monocytes Megakaryocytes
Lymphatic stem cells differentiate to produce the lymphocytes
Formed Elements
o Red Blood Cells (erythrocytes)• Small, biconcave disks• Anucleate• 4 to 6 million per mm3
• Transport oxygen• Contain hemoglobin
Respiratory pigment Oxyhemoglobin is formed when oxygen
binds with hemoglobin Hemoglobin that is not combined with
oxygen is called deoxyhemoglobin
Formed Elements
• Production of red blood cells Myeloid stem cells give rise to
erythroblasts Erythroblasts divide many times As they mature, erythroblasts gain many
molecules of hemoglobin and lose their nucleus and most of their organelles
Mature RBCs live about 120 days About 2 million RBCs are produced per
second to keep RBC count in balance Erythropoietin stimulates production and
maturation of RBCs
Formed Elements
• Destruction of red blood cells Destroyed in the liver and spleen Hemoglobin is released
Globin portion is broken down into amino acids that are recycled by the body
Iron is recovered and returned to the bone marrow for reuse
Heme portion is degraded and is excreted as bile pigments by the liver Bilirubin Biliverdin
Formed Elements
• Anemia Illness characterized by tiredness Cells are not getting enough oxygen due
to decreased hemoglobin or decreased number of red blood cells
Hemolysis can also cause anemia
Formed Elements
o White Blood Cells (leukocytes)• Usually larger than RBCs• Nucleated• Do not contain hemoglobin• About 5,000-11,000 per mm3
• Functions include Fighting infection Destroying dead or dying body cells Recognizing and killing cancerous cells
• Derived from stem cells in the red bone marrow
• Able to leave the blood stream
Formed Elements
• Types of White Blood Cells Granular leukocytes
Neutrophils Most abundant of the WBCs First type of WBC to respond to an infection Engulf pathogens during phagocytosis
Eosinophils Increase in number during parasitic worm
infections Lessen an allergic reaction during an allergic
attack Basophils
Release histamines – dilates blood vessels and causes contraction of smooth muscle
Release heparin – prevents clotting and promotes blood flow
Formed Elements
Agranular leukocytes Lymphocytes
Specific immunity Recognize and destroy cancer cells B lymphocytes produce antibodies T lymphocytes attack and destroy any cell
with a foreign antigen Monocytes
Largest of the WBCs Differentiate into macrophages that
phagocytize pathogens, old cells, and cellular debris
Stimulate other WBCs to defend the body
Platelets and Hemostasis
o Platelets• Fragments of megakaryocytes• 150,000-300,000 per mm3 of blood• Lifespan about 10 days
o Hemostasis• Cessation of bleeding• 3 events:
Vascular spasm – constriction of a broken blood vessel
Platelet plug formation In a broken blood vessel, collagen fibers are exposed Platelets adhere to collagen and aggregation of
platelets result in a platelet plug
Platelets and Hemostasis
Coagulation – blood clotting Requires many protein clotting factors Two mechanisms for activation of clotting
Intrinsic mechanism – clotting factors intrinsic to the blood – exposed collagen
Extrinsic mechanism – clotting factors extrinsic to the blood - thromboplastin
Clotting process is self-limiting and confined to the area of injury
Platelets and Hemostasis
Four steps: Prothrombin activator is
formed Prothrombin activator
converts prothrombin to thrombin
Thrombin converts fibrinogen to fibrin
Fibrin threads wind around platelet plug and trap RBCs
Platelets and Hemostasis
• Disorders of hemostasis Thrombocytopenia – low platelet count Hemophelias – inherited clotting disorders
caused by deficiencies of clotting factors Thrombus – stationary blood clot Embolus – dislodged blood clot Thromboembolism – dislodged clot blocks
a blood vessel Pulmonary thromboembolism Cerebrovascular accident or stroke
Capillary Exchange
• Lymph has the same composition as tissue fluid
• Edema Localized swelling Accumulation of tissue fluid Caused by:
Increase in capillary permeability Decrease in the uptake of water at the venous
end of blood capillaries Increase in venous pressure Insufficient uptake of tissue fluid by the
lymphatic capillaries Blocked lymphatic vessels
Blood Typing and Transfusions
o Blood transfusion• Transfer of blood from one individual
into the blood of another• Blood must be typed so that
agglutination does not occur
Blood Typing and Transfusions
o ABO Blood Groups• Based on the presence or absence of
inherited antigens• Type A blood has type A antigen and
anti-B antibodies• Type B blood has type B antigen and
anti-A antibodies• Type AB blood has both antigens and
neither antibodies• Type O blood has no AB antigens and
both antibodies
Blood Typing and Transfusions
• Agglutination occurs if antibodies in the plasma combine with the antigens on the surface of the RBC
• Type O blood is the universal donor
• Type AB blood is the universal recipient
• Autotransfusion technology and blood substitutes are alternatives to matching blood types
Blood Typing and Transfusions
o Rh Blood Groups• Rh- individuals do not have antibodies to the Rh factor until
they are exposed to it• Hemolytic disease of the newborn
May occur in subsequent pregnancies with an Rh+ baby and an Rh- mother
Bilirubin in the blood of the newborn can lead to brain damage or death
Prevented by giving Rh- women an Rh immunoglobulin injection
Effects of Aging
o Anemia• Iron deficiency anemia• Pernicious anemia
o Leukemiao Clotting disorders, such as
thromboembolism• Associated with arteriosclerosis• May be controlled by diet and
exercise