Chapter17-blood-student - OUTLINE FOR CHAPTER 17: BLOOD I....

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O UTLINE FOR C HAPTER 17: B LOOD I. B LOOD : O VERVIEW AND C OMPOSITION A. Physical Characteristics and Volume: 1. Circulation: Heart → Arteries capillary beds: (O 2 , nutrients/ CO 2 , waste) Veins Heart Lungs Heart (out aorta) 2. Characteristics: Specialized connective tissue: living cells (formed elements) in plasma (fluid) Fibrous proteins visible at clotting (no collagen, elastin) Slightly alkaline, pH=7.35-7.45 RBC/ erythrocytes: 45% volume, most dense, red, hematocrit WBC and platelets: <1% volume, white buffy coat b/t plasma and RBCs Plasma: 55% Temperature: 100.4 o F/ 38.4 o C 8% of body weight: 4-6 L B. Functions of blood 1. Distribution : 2. Regulation : 3. Protection : C. Components of Blood Structure of blood - formed elements (blood cells) suspended in a liquid (plasma) II. B LOOD P LASMA Liquid portion: 55% of blood volume Composition of plasma a. Water: b. Proteins: Albumin : the major plasma protein; acts as carrier to shuttle molecules through circulation and is a blood buffer c. Electrolytes: sodium potassium, calcium, chloride, bicarbonate d. Other substances: gases, hormones, nutrients, wastes
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III. F ORMED ELEMENTS : ERYTHROCYTES , LEUKOCYTES , PLATELETS Unique Characteristics: 1. All are not true cells (RBC-no nucleus, Platelet- cell fragments) 2. Survive only a few days 3. Do not divide: renewed by division of bone marrow cells (where they originate) Origin of Formed elements: A. Blood cells are formed from pluripotent hematopoietic stem cells 1. Originating from the pluripotent stem cells are the myeloid stem cells and lymphoid stem cells. a. Myeloid stem cells give rise to RBCs, platelets, and all leukocytes except for lymphocytes. b. Lymphoid stem cells give rise to lymphocytes. 2. Myeloid stem cells differentiate into progenitor cells or precursor cells (blast cells) which will develop into the actual formed elements of blood. 3. Lymphoid stem cells differentiate into pre-B and prothymocytes which develop into B-lymphocytes and T-lymphocytes, respectively. B. This process of hemopoiesis (or hematopoiesis ) is stimulated by several hematopoietic growth factors . These hematopoietic growth factors stimulate differentiation and proliferation of the various blood cells in the bone marrow. 1. Erythropoietin increases the number of RBC precursors. *erythropoietin is produced by the liver and kidneys 2. Thrombopoietin increases the number of platelet precursors. 3. Cytokines ( colony-stimulating factors and interleukins ) increase the number of leukocyte precursors.
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A. Erythrocytes : red blood cells (45% of total blood volume) 4.3-5.8 million cells/mm 3 1. Structure : no nucleus or organelles biconcave discs: large surface area to allow for gas exchange (the protein spectrin allows flexibility) contain hemoglobin (97% of cell): allows gas transport 2. Function and structure of hemoglobin
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Chapter17-blood-student - OUTLINE FOR CHAPTER 17: BLOOD I....

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