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BLOOD【 血液 】. Qiang XIA ( 夏强 ), PhD Department of Physiology Room C518, Block C, Research Building, School of Medicine Tel: 88208252 Email: xiaqiang@zju.edu.cn. Body Fluid = 60% of Body Weight (BW). Plasma 5% of BW. Extracellular Fluid 1/3, 20% of BW. Interstitial Fluid 15% of BW.
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BLOOD【血液】 Qiang XIA (夏强), PhD Department of Physiology Room C518, Block C, Research Building, School of Medicine Tel: 88208252 Email: xiaqiang@zju.edu.cn
Body Fluid = 60% of Body Weight (BW) Plasma 5% of BW Extracellular Fluid 1/3, 20% of BW Interstitial Fluid 15% of BW 70 kg Male, 42 L Intracellular Fluid 2/3, 40% of BW Internal environment (内环境)
Homeostasis(稳态) Homeostasis(from the Greek words for “same” and “steady”): maintenance of static or constant conditions in the internal environment Walter B. Cannon http://www.harvardsquarelibrary.org/unitarians/cannon_walter.html
Components of Homeostasis: • Concentration of O2 and CO2 • pH of the internal environment • Concentration of nutrients and waste products • Concentration of salt and other electrolytes • Volume and pressure of extracellular fluid
How is homeostasis achieved? ----Regulation Body's systems operate together to maintain homeostasis: Skin system Skeletal and muscular system Circulatory system Respiratory system Digestive system Urinary system Nervous system Endocrine system Lymphatic system Reproductive system
Components of blood • Plasma(血浆) • Blood Cells • Red Blood Cells (RBC) or Erythrocytes(红细胞) • White Blood Cells (WBC) or Leucocytes(白细胞) • Platelets (PLT) or Thrombocytes(血小板)
The hematocrit(血细胞比容) is a rapid assessment of blood composition.It is the percent of the blood volume that is composed of RBCs (red blood cells). Plasma includes water, ions, proteins, nutrients, hormones, wastes, etc.
the volume of red blood cells as a percentage of centrifuged whole blood M: 40~50% F: 37~48% Hematocrit(packed cell volume, 血细胞比容) International Council for Standardization in Haematology (ICSH) Recommendations for "Surrogate Reference" Method for the Packed Cell Volume
Physical & chemical properties of blood 1. Specific Gravity(比重) Depending on hematocrit & protein composition Whole blood: 1.050~1.060 Plasma: 1.025~1.035 Red blood cells: 1.090
2. Viscosity(粘度) • relative viscosity of whole blood 4~5 depending on hematocrit • relative viscosity of plasma 1.6~2.4 related to the protein composition of the plasma
3. Osmotic Pressure(渗透压) • The osmotic pressure of a solution depends on the number of solute particles in the solution, NOT on their chemical composition and size
Plasma osmotic pressure (~300 mOsm/L) • Crystalloid Osmotic Pressure(晶体渗透压) • Pressure generated by all crystal substances, particularly electrolytes • Important in maintaining fluid balance across cell membranes • Colloid Osmotic Pressure(胶体渗透压) • Osmotic pressure generated by plasma proteins, particularly albumin. • Approximately 25 mmHg, but important in fluid transfer across capillaries
4. Plasma pH • Normal range: 7.35~7.45 • Buffer systems(缓冲系统): NaHCO3/H2CO3, Pro-Na/Pro, Na2HPO4/NaH2PO4 Hb-K/Hb, HbO2-K/HbO2, K2HPO4/KH2PO4, KHCO3/H2CO3
Functions of blood • Transportation • O2 and CO2 • Nutrients (glucose, lipids, amino acids) • Waste products (e.g., metabolites) • Hormones • Regulation • pH • Body temperature • Protection • Blood coagulation • Immunity
Body Fluid = 60% of Body Weight (BW) Plasma 5% of BW Extracellular Fluid 1/3, 20% of BW Interstitial Fluid 15% of BW 70 kg Male, 42 L Intracellular Fluid 2/3, 40% of BW Plasma
Composition Water (92% of plasma) serves as transport medium; carries heat Proteins (6~8% of plasma) Inorganic constituents (1% of plasma) e.g., Na+, Cl-, K+, Ca2+… Nutrients glucose, amino acids, lipids & vitamins Waste products e.g., nitrogenous wastes like urea Dissolved gases O2 & CO2 Hormones
Albumins (白蛋白)(60-80% of plasma proteins) • most important in maintenance of osmotic balance • produced by liver • Globulins (球蛋白)(1-, 2-, -, -) • important for transport of materials through the blood (e.g., thyroid hormone & iron) • clotting factors • produced by liver except -globulins which are immunoglobulins (antibodies) produced by lymphocytes • Fibrinogen(纤维蛋白原) • important in clotting • produced by liver
Structure • Biconcave • No nucleus • Few organelles • Small • Hemoglobin molecules
Count RBC count M: 4.0~5.5×1012/L F: 3.5~5.0×1012/L Hemoglobin(血红蛋白) M: 120~160 g/L F: 110~150 g/L
Physiological properties Plastic deformability (可塑变形性)
d Suspension stability(悬浮稳定性) Erythrocyte Sedimentation Rate (ESR)(红细胞沉降率) • The distance that red blood cells settle in a tube of blood in one hour • Normal value [Westergren method(魏氏法,国际血液学标准化委员会推荐魏氏法为标准法)]: M: 0~15 mm/h,F: 0~20 mm/h • An indication of inflammation which increases in many diseases, such as tuberculosis & rheumatoid arthritis… International Council for Standardization in Haematology (ICSH)
Osmotic fragility (渗透脆性) the susceptibility of a red blood cell to break apart when exposed to saline solutions of a lower osmotic pressure than that of the human cellular fluid
Notice that hemolysis begins in the 0.45% tube and is complete in the 0.35% tube.
Function of RBCs 1. Transport of O2 and CO2 2. Buffering
White blood cells (Leucocytes) (白细胞) • Types of WBC
WBC count WBC Count (109/L) % Granulocytes Neutrophils 2.0~7.0 50~70 Eosinophils 0.02~0.5 0.5~5 Basophils 0~0.1 0~1 Monocytes 0.12~0.8 3~8 Lymphocytes 0.8~4.0 20~40 Total 4~10
Platelets (Thrombocytes) • Formed in the bone marrow from cells called megakaryocytes • Without nucleus, but can secrete a variety of substances • normal value: (100~300) x 109/L • Average lifespan=7~14 days • Play an important role in hemostasis
Physiological properties of platelets 1. Adhesion Platelets adhere to the vessel wall at the site of injury von Willebrand factor, vWF
2. Aggregation Platelets adhere to one another
3. Release or secretion: Platelets contain alpha and dense granules • Dense granules: containing ADP or ATP, calcium, and serotonin • α-granules: containing platelet factor 4, PDGF, fibronectin, B-thromboglobulin, vWF, fibrinogen, and coagulation factors V and XIII
Schematic drawing of the platelet (top figure), showing its alpha and dense granules and canalicular system. The bottom figure illustrates the platelet's major functions, including secretion of stored products, as well as its attachment, via specific surface glycoproteins (GP), to denuded epithelium (bottom) and other platelets (left).VWF: von Willebrand factor; TSP: thrombospondin; PF4: platelet factor 4; PDGF: platelet derived growth factor; b-TG: beta thromboglobulin; ADP: adenosine diphosphate; ATP: adenosine triphosphate.
4. Contraction Clot retraction (血块回缩)
5. Adsorption Clotting factors: I, V, XI, XIII
Hemostasis(止血) The arrest of bleeding following injury and the result of 3 interacting, overlapping mechanisms: • Vascular spasm(血管收缩) • Formation of a platelet plug(血小板血栓形成) • Blood coagulation (clotting)(血液凝固) Bleeding time (出血时间):<9 min
Signaling mediates responses to damage in a blood vessel: adjacent endothelial cells are a source of signals that influence platelet aggregation and alter blood flow and clot formation at the affected site.
Role of platelets in hemostasis • Release of vasoconstricting substances • Formation of the "platelet plug" • Promotion of blood clotting • Clot retraction
Clotting factors • Blood coagulation Clotting factor Synonyms I fibrinogen纤维蛋白原 II prothrombin凝血酶原 III tissue thromboplastin组织因子 IV Ca2+ V proaccelerin前加速素易变因子 VII proconvertin前转变素稳定因子 VIII antihemophilic factor抗血友病因子 IX plasma thromboplastin component血浆凝血活酶 X Stuart-Prower factor XI plasma thromboplastin antecedent血浆凝血活酶前质 XII contact factor接触因子 XIII fibrin-stabilizing factor纤维蛋白稳定因子
Exploration of the details of the clotting pathway has yielded detailed information about the sequence, only a portion of which is represented here. Note thrombin’s influence in three different directions.
Coagulation cascade 3 processes 2 pathways