《医学生理学 Medical Physiology》参考教材资料（PDF电子书籍）KAPLA medical. USMLE Step 1 Physiology Notes

USMLE Step 1 Physiology Notes KAPLAN medical "USMLE Is a joint program of the Federat on of state Medicai Boards of the United Sates, Ine and the Nationa Board of Medleal Examiners

~- =-- ~ USMLE'Step 1 Physiology Notes KAPLA~. meulcaI *USMLEis a joint program of the Federation of State Medical Boards of the United States, Inc. and the National Board of Medical Examiners

Author and Executive edite Robert B. Dunn, Ph D Adjunct Associate Profess Loyola University Medical Center 几L Contributors Director of medical Illustration Susan Demesquita, Ph. D Christine shaa Professor, Department of Physiology Marshall School of medicine Director of Publishing and Media Huntington, Stanley S Passo, Ph. D Associate Professor, Department of physiolo Medical Illustrators New York Medical College Rich La Rocco and Christine Schaar valhalla, ny Production editors James Porter, Ph. D University of louisville e rofessor, Department of Kathlyn McGreevy Ruthie Nussbaum Production artist Kenneth H. Ibsen, Ph D Michael Wolff Director of Academic Development professor i University of Californi Joanna mylo Irvine, CA Cover Art Mary Ruebush, Ph. D Rich larocco Adjunct Professor of Microbiolog Montana State University

>', "I ~ Authorand ExecutiveEditor Robert B.Dunn, Ph.D. Adjunct Associate Professor Department of Medicine Loyola University Medical Center Chicago, IL Contributors Susan DeMesquita, Ph.D. Professor, Department of Physiology Marshall School of Medicine Huntington, WV Directorof MedicalIllustration ChristineSchaar Directorof PublishingandMedia Michelle Covello Stanley S. Passo, Ph.D. Associate Professor, Department of Physiology New York Medical College Valhalla, NY MedicalIllustrators Rich LaRocco and Christine Schaar James Porter, Ph.D. Professor, Department of Physiology University of Louisville Louisville, KY ProductionEditors Kathlyn McGreevy Ruthie Nussbaum Kenneth H. Ibsen, Ph.D. Director of Academic Development Kaplan Medical Professor Emeritus Biochemistry University of California Irvine, CA ProductionArtist Michael Wolff CoverDesign Joanna Myllo Mary Ruebush, Ph.D. Adjunct Professor of Microbiology Montana State University Bozeman, MT CoverArt Rich LaRocco - - - f

Table of contents Preface Section 1: General Topics Chapter 1: Membrane Transport Chapter 2: Body Compartments Section II: Excitable tissue Chapter 1: lonic Equilibrium and Resting Membrane potential 35 Chapter 2: The Neuron Action Potential Chapter 3: Synaptic Transmission Section II: Peripheral Circulation Chapter 1: General Aspects of the Cardiovascular System 75 Chapter 2: Regulation of Blood Flow Section IV: Skeletal Muscle Chapter 1: Excitation-Contraction Coupling 135 Chapter 2: Skeletal Muscle Mechanics 143 Section v: Cardiac Muscle Chapter 1: Electrical Activity of the Heart Chapter 2: Heart Muscle Mechanics medical

~ Tableof Contents Preface.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . vii Section I: General Topics Chapter 1:MembraneTransport. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 Chapter2: BodyCompartments.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 Section II: Excitable Tissue Chapter1:IonicEquilibriumandRestingMembranePotential.. . . . . . . . . . 35 Chapter2: TheNeuronActionPotential.. . . . . . . . . . . . . . . . . . . . . . . . . . . . 47 Chapter3: SynapticTransmission.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53 SectionIII: Peripheral Circulation Chapter 1: GeneralAspectsof the CardiovascularSystem. . . . . . . . . . . . . . . 75 Chapter2: Regulationof BloodFlow. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 97 SectionIV:Skeletal Muscle Chapter 1:Excitation-ContractionCoupling. . . . . . . . . . . . . . . . . . . . . . . . . 135 Chapter 2: SkeletalMuscleMechanics.. . . . . . . . . . . . . . . . . . . . . . . . . . . . 143 Section V:Cardiac Muscle Chapter 1:ElectricalActivityoftheHeart. . . . .. . . . . . .. . . . . . .. . . . . . . . 167 Chapter2: HeartMuscleMechanics.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 181 meClical v

Section VI: Respiration Chapter 1: Lung Mechanics...,,,.....,.. Chapter 2: Alveolar-Blood Gas Exchange 255 Chapter 3: Transport of o, and CO and the Regulation of Respiration Chapter 4: Four Causes of Hypoxemia Section VII: Renal Physiology Chapter 1: Renal Processes 303 Chapter 2: Clearance Chapter 3: Regional Transport .............. 325 Section VIll: Acid-Base Disturbances ion IX: Endocrinology Chapter 1: Mechanisms of Hormone Action 375 Chapter 2: The Hypothalamic-Anterior Pituitary System Chapter 3: Adrenal Hormones.,...... Chapter 4: Antidiuretic Hormone(ADH)and Regulation of Osmolarity and Extracellular Fluid(ECF) 405 Chapter 5: The Endocrine Pancreas Chapter 6: Growth Hormone Chapter 7: Adrenal Medulla 429 Chapter 8: Hormonal Control of Calcium and Phosphate Chapter 9: Thyroid Hormones Chapter 10: Male Reproductive System 457 Chapter 11: Female Reproductive System 467 Section X: Gastrointestinal Physiology vi medical

? SectionVI: Respiration Chapter 1: Lung Mechanics. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 233 Chapter 2: Alveolar-Blood GasExchange.. . . . . . . . . . . . . . . . . . . . . . . . . . 255 Chapter 3: Transport of °2 and CO2 and the Regulation of Respiration. . . . . . . . . . . . . . . . . . . . . . . . 261 Chapter 4: Four Causes of Hypoxemia. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 275 Section VII: Renal Physiology Chapter 1: Renal Processes. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 303 Chapter 2: Clearance. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 319 Chapter 3: RegionalTransport. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 325 Section VIII: Acid-Base Disturbances. . . . . ,.. ..,. 359 Section IX: Endocrinology Chapter 1: Mechanismsof HormoneAction. . . . . . . . . . . . . . . . . . . . . . . . . 375 Chapter 2: The Hypothalamic-AnteriorPituitarySystem. . . . . . . . . . . . . . . 379 Chapter 3: Adrenal Hormones. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 383 Chapter 4: AntidiureticHormone(ADH) and Regulation of OsmolarityandExtracellularFluid(ECF) 405 Chapter 5: The Endocrine Pancreas. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .411 Chapter 6: Growth Hormone. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 423 Chapter 7: Adrenal Medulla. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 429 Chapter 8: HormonalControlof Calciumand Phosphate. . . . . . . . . . . . . . 433 Chapter 9: Thyroid Hormones. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 443 Chapter 10: Male ReproductiveSystem. . . . . . . . . . . . . . . . . . . . . . . . . . . . 457 Chapter 11: Female Reproductive System. . . . . . . . . . . . . . . . . . . . . . . . . . 467 Section X: Gastrointestinal Physiology. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 505 vi KAPLAN d ' . me Ica I

Preface These seven volumes of Lecture Notes represent a yearlong effort on the part of the Kaplan Medical faculty to update our curriculum to reflect the most-likely-to-be-tested material on the current USMLE Step I exam. Please note that these are Lecture Notes, not review books. The Notes were designed to be accompanied by faculty lectures-ive, on video, or on the web Reading these Notes without accessing the accompanying lectures is not an effective way to review for the usmle To maximize the effectiveness of these Notes, annotate them as you listen to lectures. To facil itate this process, we've created wide, blank margins. While these margins are occasionally punctuated by faculty high-yield"margin notes, "they are, for the most part, left blank for your notations Many students find that previewing the Notes prior to the lecture is a very effective way to pre- pare for class. This allows you to anticipate the areas where you'll need to pay particular atten tion. It also affords you the opportunity to map out how the information is going to be pre- sented and what sort of study aids(charts, diagrams, etc. )you might want to add. This strate- gy works regardless of whether you're attending a live lecture or watching one on video or the Finally, we want to hear what you think. What do you like about the notes? What do you think couldbeimprovedPleaseshareyourfeedbackbyE-mailingusatmedfeedback@kaplan.com. Thank you for joining Kaplan Medical, and best of luck on your Step I exam! Kaplan Medical medicaⅶi

..... ~ Preface These seven volumes of Lecture Notes represent a yearlong effort on the part of the Kaplan Medical faculty to update our curriculum to reflect the most-likely-to-be-tested material on the current USMLE Step 1 exam. Please note that these are Lecture Notes, not review books. The Notes were designed to be accompanied by faculty lectures-live, on video, or on the web. Reading these Notes without accessing the accompanying lectures is not an effective way to review for the USMLE. To maximize the effectiveness of these Notes, annotate them as you listen to lectures. To facil￾itate this process, we've created wide, blank margins. While these margins are occasionally punctuated by faculty high-yield "margin notes;' they are, for the most part, left blank for your notations. Many students find that previewing the Notes prior to the lecture is a very effectiveway to pre￾pare for class. This allows you to anticipate the areas where you'll need to pay particular atten￾tion. It also affords you the opportunity to map out how the information is going to be pre￾sented and what sort of study aids (charts, diagrams, etc.) you might want to add. This strate￾gy works regardless of whether you're attending a live lecture or watching one on video or the web. Finally,we want to hear what you think. What do you like about the notes? What do you think could be improved? Please share your feedback by E-mailingusatmedfeedback@kaplan.com. Thank you for joining Kaplan Medical, and best of luck on your Step 1 exam! Kaplan Medical KAPLAN ii . . me IcaI vii /

SECTION I General Topics

~ '- SECTIONI GeneralTopics

Membrane transport MEMBRANE STRUCTURE What the USMLE Requires You to Know General Features Biologic membranes are bilayers that are assembled from a mixture of lipids and proteins. The i.Factors affecting the rate of diffusion general structure of a membrane is shown in Figure 1-1-1 General charaderistics of Intrinsic protein-mediated transport proteins The differences among the vanous membrane Extracellular transport mechanisms space 0000000000-Hydrophilic er Hydrophobic end Phospholipid 000000000000000 Cytoplasm Figure 1-1-1. The Structure of Biologic Membranes Lipids The lipid component is composed primarily of a bilayer of phospholipids, with the hydrophilic (water-soluble)ends facing the aqueous environment and the hydrophobic(water-insoluble ends facing the interior of the membrane. Other major components include unesterified cholesterol and glycolipid Proteins The proteins are responsible for the dynamic aspects of membrane function. There are two main types of membrane proteins. Integral membrane proteins: They are embedded in the lipid bilayer and cannot be removed without disrupting the bilayer. They include channels, pumps, carriers, and receptors. Peripheral proteins: They bind to the hydrophilic polar heads of the lipids or to the integral proteins. Peripheral proteins contribute to the cytoskeleton and the glycocalyx glycolipid and glycoprotein that cover the cell membrane) KAPLA edical

MembraneTransport MEMBRANESTRUCTURE GeneralFeatures Biologic membranes are bilayers that are assembled from a mixture of lipids and proteins. The general structure of a membrane is shown in Figure I-I-I. Hydrophilice~ Phospholipid Hydrophobic~ Figure 1-1-1.The Structure of Biologic Membranes Lipids The lipid component is composed primarily of a bilayer of phospholipids, with the hydrophilic (water-soluble) ends facing the aqueous environment and the hydrophobic (water-insoluble) ends facing the interior of the membrane. Other major components include unesterified cholesterol and glycolipids. Proteins The proteins are responsible for the dynamic aspects of membrane function. There are two main types of membrane proteins. Integral membrane proteins: They are embedded in the lipid bilayer and cannot be removed without disrupting the bilayer. They include channels, pumps, carriers, and receptors. Peripheral proteins: They bind to the hydrophilic polar heads of the lipids or to the integral proteins. Peripheral proteins contribute to the cytoskeleton and the glycocalyx (glycolipid and glycoprotein that cover the cell membrane). ~ """'" " What the USMLE !,~,!~~,~,~,,!~.~~!5!!~ . Factorsaffectingthe rateof diffusion . General characteristics of protein-mediatedtransport . The differences among the various membrane transport mechanisms meClical 3

USMLE Step 1: Physiology MEMBRANE TRANSPORT Diffusion Factors that affect the rate of diffusion(D)of a substance between two compartments separat ed by a membrane are given in the following formula D∝ △P×SA×So T×VMW AP= concentration gradient across the membrane. The greater the concentration gradient, the ter tbe rate of diffusio SA= surface area of the membrane. The greater the surface area, the greater the rate of diffu sion (For example, exercise opens additional pulmonary capillaries, increasing the surface area for exchange. Emphysema decreases the surface area for exchange. SOL= solubility in the membrane or permeability. The more soluble the substance, the faster it will diffuse. Generally CO, diffuses faster across membranes than O, because CO, exhibits greater solubility T= thickness of the membrane. The thicker the membrane the slower the rate of diffusion (e. g, lung fibrosis) MW =molecular weight. This factor is not important clinically The molecules of eacb species diffuse independently. There is no durect interaction among molecules during diffusion. If the inspired nitrogen in room air is replaced elium, the rate of oxygen and carbon dioxide diffusion will be unaffected Osmosis Osmosis is the diffusion of water across a semipermeable or selectively permeable membrane. Water will diffuse from a region of higher water concentration to a region of lower water con- centration. The water concentration of a solution is determined by the concentration of solute The greater the solute concentration, the lower the water concentration. The basic principles are demonstrated in Figure 1-1-2. 0;0 o;。 Figure 1-1-2 This figure shows two compartments separated by a membrane that is permeable to water but not to solute. Side b has the greater concentration of solute(circles)and thus a lower water con- centration than side A. As a result, water wi diffuse from A to B, and the height of column B will rise, and that of A will fall 4 medical

"... USMLEStep1: Physiology 4 KAPLA~. meulCa I MEMBRANETRANSPORT Diffusion Factors that affectthe rate of diffusion (D) of a substance between two compartments separat￾ed by a membrane are given in the following formula: D ex:LlP X SA X SOL T X VMW LlP=concentration gradient across the membrane. The greater the concentration gradient, the greater the rate of diffusion. SA = surface area of the membrane. The greater the surface area, the greater the rate of diffu￾sion. (For example, exerciseopens additional pulmonary capillaries,increasing the surface area for exchange.Emphysema decreases the surface area for exchange.) SOL = solubility in the membrane or permeability. The more soluble the substance, the faster it will diffuse. Generally CO2 diffuses faster across membranes than °2 because CO2 exhibits greater solubility. T = thickness of the membrane. The thicker the membrane, the slower the rate of diffusion, (e.g., lung fibrosis). MW = molecular weight. This factor is not important clinically. The molecules of each species diffuse independently. There is no direct interaction among molecules during diffusion. If the inspired nitrogen in room air is replaced by helium, the rate of oxygen and carbon dioxide diffusion will be unaffected. Osmosis Osmosis is the diffusion of water across a semipermeable or selectivelypermeable membrane. Water will diffuse from a region of higher water concentration to a region of lower water con￾centration. The water concentration of a solution is determined by the concentration of solute. The greater the solute concentration, the lower the water concentration. The basicprinciples are demonstrated in Figure 1-1-2. A B Figure 1-1-2 This figure shows two compartments separated by a membrane that is permeable to water but not to solute. SideBhas the greater concentration of solute (circles)and thus a lowerwater con￾centration than side A. As a result, water will diffuse from A to B, and the height of column B will rise, and that of A will fall. I 0 0 I 0 0 I I 0 0 0 0 I 0 0 I I 0 0 I 0 0 I 0 0 I

Membrane transport mOsm(milliosmolar)or mOsm/ =an index of the concentration of particles per liter of solu mM(millimolar)or mML an index of the concentration of molecules dissolved per liter of solution isotonic solutions 300 mOsm= 150 mM NaCl (one NaCl molecule yields two particles 300 mOsm= 300 mM glucose The 300 mOsm is rounded off from the true value of 285 to 290 mOsm PROTEIN (CARRIER)-MEDIATED TRANSPORT Protein carriers transport substances that cannot readily diffuse across a membrane. There are no transporters for gases and other lipid-soluble substances because these substances read penetrate cell membranes. Characteristics Common to All Protein-Mediated Transport Rate of transport: A substance is transported more rapidly than it would be by diffusion, because the membrane is not usually permeable to any substance for which there is a transport protein Saturation kinetics: As the concentration of the substance initially increases on one side of the embrane, the transport rate will increase. Once the transporters become saturated, transport rate is maxima (TM=transport maximum). TM is the transport rate when the carriers are sat- urated. It is directly proportional to the number of functioning transporters Chemical specificity: To be transported, the substance must have a certain chemical structure Generally, only the natural isomer will be transported (e.g., D-glucose but not L-glucose Competition for carrier: Substances of similar chermical structure may compete for the same trans porter. For example, glucose and galactose will generally compete for the same transport protein types of Protein Transport acilitated Transport( Passive Process Net movement is always down a concentration gradient. It is the concentration gradient that drives both facilitated transport and simple diffusion Active Transport(Active Process Net movement is against a concentration gradient Requires chemical energy (ATP) medical 5

..... MembraneTransport mOsm (milliosmolar) or mOsmIL =an index of the concentration of particles per liter of solu￾tion. mM (millimolar) or mM/L =an index of the concentration of molecules dissolved per liter of solution. isotonic solutions =300 mOsm = 150 mM NaCl (one NaCl molecule yields two particles in solution). 300 mOsm =300 mM glucose The 300 mOsm is rounded off from the true value of 285 to 290 mOsm. PROTEIN(CARRIER)-MEDIATEDTRANSPORT Protein carriers transport substances that cannot readily diffuse across a membrane. There are no transporters for gases and other lipid-soluble substances because these substances readily penetrate cell membranes. CharacteristicsCommonto All Protein-MediatedTransport Rate of transport: A substance is transported more rapidly than it would be by diffusion, because the membrane is not usually permeable to any substance for which there is a transport protein. Saturation kinetics: As the concentration of the substance initially increases on one side of the membrane, the transport rate will increase. Once the transporters become saturated, transport rate is maximal (TM =transport maximum). TM is the transport rate when the carriers are sat￾urated. It is directly proportional to the number of functioning transporters. Chemical specificity: To be transported, the substance must have a certain chemical structure. Generally, only the natural isomer will be transported. (e.g., D-glucose but not L-glucose). Competition for carrier: Substances of similar chemical structure may compete for the same trans￾porter. For example, glucose and galactose will generally compete for the same transport protein. Typesof ProteinTransport FacilitatedTransport(PassiveProcess) Net movement is always down a concentration gradient. It is the concentration gradient that drives both facilitated transport and simple diffusion. ActiveTransport(ActiveProcess) Net movement is against a concentration gradient Requires chemical energy (ATP) iiieilical 5

USMLE Step 1: Physiology Primary and Secondary Transport In primary active transport, ATP is consumed directly by the transporting protein,(e.g, the Na/K-ATPase pump, or the calcium pump of the sarcolemma). econdary active transport depends indirectly on aTP as a source of energy, as in the cotran port(molecules move in the same direction)of Nat and glucose in the renal tubules and gut This process depends on ATP utilized by the Na/K-ATPase pump. s mucose Lumin Membrane Glucose moved up a concentration adient via secondary activ FIgure 1-1-3 Renal Tubule or Small Intestine Figure 1-1-3 represents a renal proximal tubular cell or a cell lining the small intestine. In this figure, the Na/K-ATPase pump maintains a low intracellular sodium concentration, which cre- ates a large gradient across the cell membrane. It is this sodium gradient across the luminal membrane that drives secondary active transport of glucose In summary, the secondary active transport of glucose Depends upon luminal sodium Is stimulated by luminal sodium(via increased sodium gradient Is linked to the uptake of sodium

r'" USMLEStep1: Physiology 6 meClical Primary and Secondary Transport In primary active transport, ATP is consumed directly by the transporting protein, (e.g., the Na/K-ATPasepump, or the calcium pump of the sarcolemma). Secondary active transport depends indirectly on ATP as a source of energy,as in the cotrans￾port (molecules move in the same direction) of Na+ and glucose in the renal tubules and gut. This process depends on ATP utilized by the Na/K-ATPasepump. ISF Na Na+ Glucose K+ Luminal Membrane Basal Membrane Glucose moved up a concentration gradient via secondary active transport Figure 1-1-3.Renal Tubule or Small Intestine Figure 1-1-3 represents a renal proximal tubular cell or a cell lining the small intestine. In this figure, the Na/K-ATPase pump maintains a low intracellular sodium concentration, which cre￾ates a large gradient across the cell membrane. It is this sodium gradient across the luminal membrane that drives secondary active transport of glucose. In summary, the secondary active transport of glucose Depends upon luminal sodium Is stimulated by luminal sodium (via increased sodium gradient) Is linked to the uptake of sodium