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Blood Physiology / 血液的主要功能. 赖蒽茵 浙江大学医学院生理系 求是特聘教授 浙江省“千人计划”人才, 博导 laienyin@zju.edu.cn. 13:15-14:00 , May 12 , 2014 ,基础医学导论 紫金港东 2-203 , 2013 级五年制临床,共 150 人. 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 Physiology / 血液的主要功能 赖蒽茵 浙江大学医学院生理系 求是特聘教授 浙江省“千人计划”人才,博导laienyin@zju.edu.cn 13:15-14:00,May 12,2014,基础医学导论 紫金港东2-203,2013级五年制临床,共150人
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)
Plasma 5% of BW Extracellular Fluid 1/3, 20% of BW Interstitial Fluid 15% of BW Internal Environment
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? 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.
Hematocrit(packed cell volume, 血细胞比容) the volume of red blood cells as a percentage of centrifuged whole blood M: 40~50% F: 37~48%
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
Properties of blood 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
Properties of blood 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
Properties of blood • 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
Properties of blood 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 Intracellular Fluid 2/3, 40% of BW Plasma
Plasma composition Water (92% of plasma) serves as transport medium; carries heat proteins Nutrients glucose, amino acids, lipids & vitamins Waste products 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
Erythrocytes 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)
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, M: 0~15 mm/h,F: 0~20 mm/h • An indication of inflammation which increases in many diseases, such as tuberculosis & rheumatoid arthritis…
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
Function of RBCs 1. Transport of O2 and CO2 2. Buffering
Hemocytoblast stem cell • Stem cell becomes committed • Early erythroblasts have ribosomes早期的红细胞有核糖体 • Erythroblasts accumulate iron and hemoglobin红细胞积聚铁和血红蛋白 • Normoblasts eject organelles • Released as erythrocyte
Regulation of Erythropoiesis 1. Erythropoietin(促红细胞生成素) 2. Hormones: Androgen(雄激素) Hypoxia-inducible factor-1, HIF-1
Destruction of RBC average lifespan = about 120 days • Macrophages engulf(吞噬)old RBCs • Iron is salvaged • Heme degrades into bilirubin
Anemia(贫血) • Anemia is defined as a qualitative or quantitative deficiency of hemoglobin, a protein found inside red blood cells (RBCs) • The three main classes of anemia: • excessive blood loss (acutely such as a hemorrhage or chronically through low-volume loss) • excessive blood cell destruction (hemolysis) • deficient red blood cell production (ineffective hematopoiesis)
Iron deficiency anemia 缺铁性贫血
Megaloblastic anemia 巨幼红细胞性贫血
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
Leukopoiesis (白细胞生成) • Myeloblasts (原始粒细胞) become all of the granular leukocytes (白细胞) • Monoblasts become monocytes • Lymphoblasts become lymphocytes
Platelets • Formed in the bone marrow from cells called megakaryocytes (巨核细胞) • 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 (聚合) Platelets adhere to one another
Phospholipid (磷脂) Phospholipase A2 Arachidonic Acid (花生四烯酸) Cyclo-oxygenase PGG2 & PGH2 Thromboxane synthase (Platelets) Prostacyclin synthase (Vascular endothelium) TXA2 PGI2 Aggregation Anti-aggregation Contraction Relaxation
4. Contraction Clot retraction (血块回缩)