Summary of Nerve and Muscle Physiology

Contents Chapter 1. OVERVIEW OF THE NERVOUS SYSTEM (L. Pinar) Organization of the Central Nervous System....................................................... 4 General Functions of the Main Parts of the Brain................................................ 4 Cerebrum............................................................................................................... 4 Brainstem............................................................................................................... 5 Cerebellum............................................................................................................ 6 Meninges (Meninx).............................................................................................. 6 Cerebrospinal fluid (CSF) .................................................................................... 6 Blood Brain Barrier (BBB)..................................................................................... 6 Cranial Nerves....................................................................................................... 7 REFERENCES............................................................................................................... 9 Chapter 2. BIOELECTRIC POTENTIALS OF THE EXCITABLE CELL (L. Pinar) Resting Membrane Potential................................................................................. 13 Generation of the resting membrane potential............................................ 14 Individual Ions Involved in the Resting Membrane Potential..................... 15 Nernst Potentials: Equilibrium Potentials of Ions.......................................... 15 The Equilibrium (Nernst) Potential of Potassium.......................................... 16 The Equilibrium (Nernst) Potential of Sodium............................................... 17 Calculation of the Sum Effects of Several Permeable Ions on the Resting Membrane Potential: Goldman-Hodgkin-Katz Equation............... 18 Gibbs Donnan Effect ......................................................................................... 18 The Effects of Na-K ATPase on Membrane Potential................................... 20 The Membrane of Excitable Cell...................................................................... 20 Action Potential.................................................................................................. 22 Investigation of Ion Channels: Voltage Clamp and Patch Clamp Techniques 26 REFERENCES............................................................................................................ 27 Chapter 3. NERVE PHYSIOLOGY (L. Pinar) Glial Cells ................................................................................................................. 31 Astrocytes............................................................................................................ 31 Functions of Astrocytes..................................................................................... 32 Oligodendrocytes............................................................................................... 32 Schwann cells..................................................................................................... 33 Microglia.............................................................................................................. 33 Ependymal Cells................................................................................................. 33 Neurons..................................................................................................................... 33 The Functional and Structural Parts of a Typical Neuron............................. 33 Myelinated and Unmyelinated Neurons........................................................ 35 Distribution of Ion Channels in Neurons........................................................ 36 Conduction of the Action Potential Along the Axons.................................. 37 Orthodromic and Antidromic Impulse Conduction...................................... 39 Mixed Nerves...................................................................................................... 39 Nerve Fiber Types.............................................................................................. 40 Transport of Proteins in the Axons ................................................................ 41 Neurotrophic Factors......................................................................................... 41 Degeneration and Regeneration of Nerve Fibers........................................ 42 Demyelinating Diseases................................................................................... 43 Effects of Changing Concentrations of Plasma Ions on the Excitability of Nerves......................................................................................... 43 Rhythmicity of Some Excitable Tissues........................................................... 45 Electrotonic Potentials, Local Response ........................................................ 45 Clinical Aspects........................................................................................................ 46 Channelopathies (Ion Channel Myopathies)................................................. 46 REFERENCES............................................................................................................ 47 Chapter 4. MUSCLE PHYSIOLOGY (L. Pinar) Skeletal Muscle........................................................................................................ 51 Morphology of Skeletal Muscle ....................................................................... 51 Cross Striation..................................................................................................... 52 Sarcolemma........................................................................................................ 54 Sarcotubular System.......................................................................................... 54 Contractile Proteins of Skeletal Muscle.......................................................... 55 Thin filaments..................................................................................................... 55 Thick Filaments .................................................................................................. 56 Dystrophin-Glycoprotein Complex................................................................. 56 Electrical Characteristics of Skeletal Muscles................................................. 57 The Flux of Ions .................................................................................................. 57 Contraction................................................................................................................ 58 Muscle Twitch..................................................................................................... 58 Molecular Basis of Contraction......................................................................... 58 Excitation-Contraction Coupling...................................................................... 59 Transmission of the Excitation to Contraction............................................... 60 Sliding Mechanism............................................................................................. 60 Relaxation............................................................................................................ 60 Fatigue................................................................................................................. 61 Rigor Complex ................................................................................................... 61 Rigor Mortis......................................................................................................... 61 The Length and Tension Relationship of Contraction.................................. 61 Types of Excitation............................................................................................. 62 Types of Contraction.......................................................................................... 62 Energy Mechanism of Muscle Contraction........................................................ 63 Muscle Fiber Types............................................................................................. 64 Properties of Entire Muscles................................................................................. 65 Motor Unit............................................................................................................ 65 Grading of Muscular Activity............................................................................. 66 Summation of the Contractions: Strengthening of the Muscle Twitches...... 67 Temporal (Time-Related) Summation............................................................ 67 Spatial Summation............................................................................................. 68 Denervation Sensitivity of Skeletal Muscle, Denervation Potentials......... 68 Diseases of Muscle ................................................................................................. 70 Muscular Dystrophy........................................................................................... 70 Channelopathies................................................................................................ 70 Smooth Muscle......................................................................................................... 71 REFERENCES............................................................................................................ 73 Chapter 5. EXERCISE PHYSIOLOGY ( L. Pinar) Benefits of Regular (long-term) Aerobic Exercise............................................ 77 Quantitative Values for Physical Capacities...................................................... 78 Strength, Power and Endurance of the Muscles........................................... 78 Energy Systems of Exercises............................................................................. 79 Recovery of the Muscle Metabolic System after Exercise........................... 79 Oxygen Debt....................................................................................................... 80 Maximal Resistance Training............................................................................ 80 Muscle Training for Hypertrophy and Strengthening .................................. 81 Effects of the Exercise on the Respiratory System .......................................... 81 Oxygen Consumption (VO2) ............................................................................ 82 Effects of the Exercise on the Cardiovascular System .................................... 82 Summary.............................................................................................................. 83 Maximal Oxygen Consumption....................................................................... 84 VO2 max Levels................................................................................................... 84 Measurement of VO2 max....................................................................................... 84 Submaximal Level of Exercises........................................................................ 85 Uth-Sorenson-Overgaard-Pederson Estimation ........................................... 85 Cooper Test......................................................................................................... 85 6-Minute Walk Test ........................................................................................... 86 Body Heat in Exercise............................................................................................. 86 Heatstroke........................................................................................................... 86 Doping Drugs...................................................................................................... 87 REFERENCES............................................................................................................ 87 Chapter 6. SYNAPTIC TRANSMISSION (L. Pinar) Types of Synapses................................................................................................... 91 Morphology of Chemical Synapses................................................................. 92 Presynaptic and Postsynaptic Structures........................................................ 93 Fusion................................................................................................................... 94 Divergence and Convergence......................................................................... 94 Excitatory and Inhibitory Postsynaptic Potentials........................................... 94 Excitatory Post Synaptic Potential ................................................................... 95 Inhibitory Post Synaptic Potential.................................................................... 96 Temporal and Spatial Summation.................................................................... 97 Slow Post Synaptic Potentials........................................................................... 98 Function of Dendrites........................................................................................ 98 Inhibition and Facilitation at Synapses............................................................... 98 Direct and Indirect Inhibitions.......................................................................... 98 Presynaptic Inhibition and Facilitation.......................................................... 100 Organization of Inhibitory Systems............................................................... 101 Neuromuscular Transmission .......................................................................... 101 Neuromuscular (or Myoneural) Junction..................................................... 101 Drugs That Affect the Transition of Action Potential from Nerve to Muscle 104 Blockers............................................................................................................. 104 Drugs That Block Acetylcholinesterase........................................................ 104 Clinical Aspects .................................................................................................... 105 Myasthenia Gravis ........................................................................................... 105 Lambert-Eaton Syndrome .............................................................................. 105 Neurotransmitters................................................................................................. 106 Neuromodulators............................................................................................. 106 Receptors.......................................................................................................... 107 Mechanism of Reuptake................................................................................. 108 Monoamine Transmitters.................................................................................... 108 Acetylcholine ................................................................................................... 108 ACh Receptors.................................................................................................. 108 Serotonin........................................................................................................... 109 Serotonin Receptors........................................................................................ 109 Histamine ......................................................................................................... 109 Catecholamines .............................................................................................. 109 Dopamine ........................................................................................................ 110 Excitatory Amino Acids....................................................................................... 110 Glutamate.......................................................................................................... 110 Glutamate Receptors....................................................................................... 110 Inhibitory Amino Acids....................................................................................... 111 Glycine .............................................................................................................. 111 GABA (Gamma Amino Butyric Acid)............................................................. 111 GABA Receptors............................................................................................... 111 Large Molecule Transmitters ............................................................................. 112 Substance P....................................................................................................... 112 Opioid Peptides................................................................................................ 112 Clinical Aspects .................................................................................................... 112 Excitotoxins....................................................................................................... 112 Role of Serotonin in Mood and Behavior..................................................... 113 Phenylketonuria............................................................................................... 113 Schizophrenia .................................................................................................. 113 REFERENCES.......................................................................................................... 113 Chapter 7. CUTANEOUS SENSES and PAIN (T. Yörükan) Introduction to the Special Senses..................................................................... 117 Types of Sensation................................................................................................ 117 Touch and Pressure......................................................................................... 117 Vibration............................................................................................................ 119 Proprioception.................................................................................................. 119 Tickle and Itch................................................................................................... 119 Thermal Senses................................................................................................ 119 Two-Point Discrimination............................................................................... 120 Epicritic sensibility or localisation.................................................................. 120 Topognosis (localisation of stimuli)............................................................... 121 Pain or Nociception.............................................................................................. 121 The Gating Theory............................................................................................ 124 Somatic Pain............................................................................................................... 124 Visceral Pain........................................................................................................... 124 Referred Pain.................................................................................................... 124 Transmission..................................................................................................... 126 Lateral Inhibition.............................................................................................. 128 Analgesia........................................................................................................... 128 Analgesic Substances............................................................................................ 128 Opiate Peptides ............................................................................................... 128 Effect of Acetylcholine on Pain .................................................................... 129 Cannabinoids in Pain Relief............................................................................ 129 Pain Suppression in the Brain and Spinal Cord ........................................... 129 Clinical Aspects ............................................................................................... 130 Neuropathic Pain................................................................................................... 131 Sensory Symptoms of Spinal Cord Diseases................................................ 132 Cortical Representation.................................................................................. 132 Clinical Aspects................................................................................................ 133 REFERENCES.......................................................................................................... 134 Chapter 8. PHYSIOLOGY OF VISION (T. Yörükan) Structure of the Eye............................................................................................... 137 The Sclera.......................................................................................................... 138 The Choroid...................................................................................................... 140 The Retina......................................................................................................... 142 The Optical System of the Eye- the first function of the eye........................ 146 Lens strength and normal vision................................................................... 148 Near Point Convergence Reflex.................................................................... 150 Visual Fixation Reflex....................................................................................... 150 Binocular Vision ............................................................................................... 150 Visual Acuity...................................................................................................... 151 Physiologic Mechanisms in Vision - the second step in vision.................. 151 Scotopic Vision...................................................................................................... 152 Photopic Vision..................................................................................................... 152 Photochemical and Bioelectric Processes in Scotopic vision................... 152 Mechanism of Excitation................................................................................. 153 Physiologic Nystagmus................................................................................... 156 Colour Vision......................................................................................................... 156 Transmission of signals from the retina to the Visual centres ................. 158 Lesions at different levels of the Optic tract .............................................. 161 Eye movements .............................................................................................. 162 Visual Field and Perimeter.............................................................................. 162 Scotoma............................................................................................................. 162 REFERENCES.......................................................................................................... 163 Chapter 9. AUDITORY PHYSIOLOGY (T. Yörükan) Perilymph and Endolymph............................................................................. 171 Sound - Physical characteristics........................................................................ 171 The Decibel ...................................................................................................... 172 Summary of the Auditory process..................................................................... 172 Cochlear Sound Transmission........................................................................ 172 Place Theory of Cochlear Function............................................................... 175 Transmission to the Auditory Cortex................................................................ 176 The Types of Hearing Loss.................................................................................. 177 Equilibrium............................................................................................................ 177 Disturbances of Balance................................................................................. 181 REFERENCES.......................................................................................................... 181 Chapter 10. CHEMICAL SENSES OF TASTE AND SMELL OR GUSTATION AND OLFACTION (T. Yörükan) Taste or Gustation................................................................................................. 185 General mechanism of stimulation............................................................... 186 Localisation....................................................................................................... 188 Transmission......................................................................................................... 189 Smell or Olfaction................................................................................................. 190 Vomeronasal Organ......................................................................................... 191 Mechanism of Excitation................................................................................. 192 Sensation modalities....................................................................................... 192 Transmission......................................................................................................... 193 Disturbances of Olfaction............................................................................... 195 REFERENCES.......................................................................................................... 195 Chapter 11. AUTONOMIC NERVOUS SYSTEM (T. Yörükan) Sympathetic Division........................................................................................... 200 Parasympathetic Division................................................................................... 201 Synapses.................................................................................................................. 202 Autonomic Transmitters................................................................................. 202 Sympathetic postganglionic fibre Effector Organ Synapse....................... 204 Regulation of Norepinephrine Release and Synthesis.............................. 204 Adrenergic Receptors..................................................................................... 204 Alpha Receptors............................................................................................... 205 Beta Receptors................................................................................................. 205 Acetylcholine Receptors................................................................................. 206 Denervation Hypersensitivity............................................................................ 207 Responses in Effector Organs............................................................................. 207 The actions of sympathetic nerves on effector organs............................. 207 Actions of Parasympathetic Nerves on Effector Organs............................ 209 Cranial Division..................................................................................................... 209 Responses of Effectors to Autonomic Nerve Impulses................................. 210 Autonomic reflexes......................................................................................... 212 Central Control of Autonomic functions........................................................... 213 REFERENCES.......................................................................................................... 214 Chapter 12. MOTOR FUNCTIONS OF THE CENTRAL NERVOUS SYSTEM (L. Pinar) Three Main Levels of the Central Nervous System Involved in Motor Functions 217 Spinal cord (Medulla Spinalis) Level.............................................................. 217 Lower Brain Level............................................................................................ 217 Upper Brain Level, Cortical Level.................................................................. 218 The Simplest Motor Activities Of the Spinal Cord.......................................... 219 Stretch Reflex................................................................................................... 219 The Effect of the Gamma Motor Neurons.................................................... 222 Reciprocal Innervation and Inhibition........................................................... 223 Golgi Tendon Reflex........................................................................................ 223 Pathological Reflexes...................................................................................... 225 Withdrawal Reflex (Flexion Reflex)............................................................... 225 Spinal Shock...................................................................................................... 226 Brown Sequard Syndrome ............................................................................. 227 Mass Reflex....................................................................................................... 227 Clinical Aspects..................................................................................................... 229 Amyotrophic Lateral Sclerosis (Motor Neuron Disease)............................ 229 Brainstem and Reticular Formation.................................................................. 230 Reticular Facilitatory (Excitatory) Area.......................................................... 230 Reticular Inhibitory Area................................................................................. 231 Functions of the Neocortex................................................................................. 232 Cerebral Dominance ...................................................................................... 232 Control of Motor Functions................................................................................. 234 Motor Areas in the Cerebral Cortex ............................................................. 235 Primary Motor Cortex ..................................................................................... 235 Premotor Cortex.............................................................................................. 236 Supplementary Motor Cortex........................................................................ 236 Somatic Sensory Area in Motor activity........................................................ 237 Initiation of the Motor Commands by the Cerebral Cortex...................... 237 Control of the Axial and Distal Muscles of the Body..................................... 238 Corticospinal Tracts............................................................................................. 240 Lateral Corticospinal Tract (Pyramidal tract)................................................ 240 Anterior (Ventral) Corticospinal Tract .......................................................... 241 Corticobulbar Tract.......................................................................................... 242 Rubrospinal Tract.............................................................................................. 242 Extrapyramidal System (Ventromedial System Tracts) .............................. 243 Pontine Reticulospinal Tract (tr. Reticulospinalis medialis)....................... 243 Medullary Reticulospinal Tract (tr. Reticulospinalis lateralis).................... 243 Medial and Lateral Vestibulospinal Tracts.................................................... 243 Tectospinal Tract.............................................................................................. 244 The Inhibitory Areas of Central Nervous System ....................................... 244 Decerebrate Rigidity....................................................................................... 245 Decorticate Rigidity (Spasticity)..................................................................... 246 Lower and Upper Motor Neurons and Their Lesions ................................ 246 Lesions of Cortical Areas................................................................................. 247 Cerebral Palsy (CP).......................................................................................... 249 Impairment of the Sensorimotor Integration ............................................. 249 Basal Ganglia.......................................................................................................... 250 Direct Tract ....................................................................................................... 252 Indirect Tract..................................................................................................... 252 Neuronal Circuits of the Basal Ganglia............................................................. 253 Putamen Circuit............................................................................................... 253 Caudate Circuit................................................................................................. 254 Metabolic Properties of the Basal Ganglia................................................... 255 Clinical Aspects..................................................................................................... 255 Huntington's disease....................................................................................... 255 Parkinson's Disease (Paralysis Agitans)........................................................ 256 Cerebellum.............................................................................................................. 257 Function............................................................................................................. 257 Afferent Tracts to the Cerebellum from the Brain .................................... 259 Afferent Tracts to the Cerebellum from the Periphery............................. 259 Efferent Tracts from the Cerebellum............................................................ 260 Functional Unit of the Cerebellum............................................................... 260 Function of the Lateral Hemispheres........................................................... 262 Romberg Test................................................................................................... 262