human anatomy, 3rd edition prentice hall, © 2001 blood chapter 20
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Human Anatomy, 3rd editionPrentice Hall, © 2001
Blood
Chapter 20
Human Anatomy, 3rd editionPrentice Hall, © 2001
Introduction– Functions
• Transport medium
• Regulation
• Protection
– Composition• Plasma – fluid
• Formed elements – cells & cell fragments
– Volume varies• Average = 5 liters
Human Anatomy, 3rd editionPrentice Hall, © 2001
Plasma– = about 55% of the blood– Composition
• Mostly water
• Plasma proteins
• Dissolved foods, wastes, gases, ions
– Differences between plasma and intersititial fluid
• Plasma has more dissolved gases
• Plasma has more proteins
• Concentrations of small molecules are similar
Human Anatomy, 3rd editionPrentice Hall, © 2001
Plasma Proteins– Most are made by the liver
• Albumins – transport fatty acids & steroids
• Globulins – immune functions
• Fibrinogen – blood clotting
Human Anatomy, 3rd editionPrentice Hall, © 2001
Composition of Blood
Human Anatomy, 3rd editionPrentice Hall, © 2001
Formed Elements– Blood cells and cell fragments– Produced by hemopoiesis
• Arise from stem cells called hemocytoblasts
– Types of formed elements• Erythrocytes – red blood cells (RBCs)
• Leukocytes – white blood cells (WBCs)
• Thrombocytes – platelets
Human Anatomy, 3rd editionPrentice Hall, © 2001
Erythrocytes– Biconcave, have no nuclei (or other organelles)
• Lifespan = about 120 days
– Production occurs in the red bone marrow• Erythropoiesis
• Controlled by the hormone erythropoietin
– Functions• Transport O2 & some CO2
– Bound to hemoglobin
– Anemia– Polycythemia (erythrocytosis)
Human Anatomy, 3rd editionPrentice Hall, © 2001
A Red Blood Cell
Human Anatomy, 3rd editionPrentice Hall, © 2001
SEM of RBCs
Human Anatomy, 3rd editionPrentice Hall, © 2001
Hemoglobin
Human Anatomy, 3rd editionPrentice Hall, © 2001
Numbers of RBCs– Normally 4.3-5.8 million cells/mm3 of blood
• Males = 5.1-5.8 million/mm3
• Females = 4.3-5.2 million/mm3
– Numbers affect viscosity of blood– The percentage of erythrocytes, by volume, in
whole blood is the hematocrit• Males = 45%
• Females = 42%
Human Anatomy, 3rd editionPrentice Hall, © 2001
Leukocytes– About 5000 – 10,000/mm3 of blood– Produced by leukopoiesis in red bone marrow– Location – mostly in peripheral tissues– Functions
• Defense against pathogens
• Removal of toxins, wastes, abnormal or damaged cells
– As large or larger than RBCs, contain nuclei
Human Anatomy, 3rd editionPrentice Hall, © 2001
Types of WBCs– Granulocytes have granules in their cytoplasm
• Neutrophils are phagocytic towards bacteria– 55-65% of circulating WBCs
• Eosinophils are involved in allergic reactions and parasitic infections
– 2-4% of circulating WBCs
• Basophils exaggerate inflammation at the site of an injury
– Less than 1% of circulating WBCs
Human Anatomy, 3rd editionPrentice Hall, © 2001
A Neutrophil
Human Anatomy, 3rd editionPrentice Hall, © 2001
An Eosinophil
Human Anatomy, 3rd editionPrentice Hall, © 2001
A Basophil
Human Anatomy, 3rd editionPrentice Hall, © 2001
Types of WBCs– Agranulocytes do not have granules in their
cytoplasm• Monocytes are phagocytes and form the
macrophages of the tissues– 2-8% of the WBC population
• Lymphocytes are responsible for specific immunity– B lymphocytes produce antibodies
– T lymphocytes attack foreign cells directly
– 20-30% of the WBC population
Human Anatomy, 3rd editionPrentice Hall, © 2001
A Monocyte
Human Anatomy, 3rd editionPrentice Hall, © 2001
A Lymphocyte
Human Anatomy, 3rd editionPrentice Hall, © 2001
Thrombocytes– Formed from fragments of large cells called
megakaryocytes– Have no nuclei, lifespan is 10 – 12 days– Number about 350,000/mm3 of blood– Function
• Involved in the clotting mechanism
Human Anatomy, 3rd editionPrentice Hall, © 2001
Platelet Formation
Human Anatomy, 3rd editionPrentice Hall, © 2001
Origins & Differentiation of Blood Cells
Human Anatomy, 3rd editionPrentice Hall, © 2001
Blood Types– Antigens are specific proteins on RBC
membranes• Blood is classified based on these antigens
• A, B, O
• Rh
– Antigens are accompanied by other proteins in plasma – antibodies
– Specific antibodies bind with their antigens, causing agglutination
Human Anatomy, 3rd editionPrentice Hall, © 2001
Blood Types