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THE PERIPHERAL NERVOUS SYSTEM D. C. MIKULECKY PROFESSOR OF PHYSIOLOGY AND FACULTY MENTORING PROGRAM ORGANIZATION OF THE NERVOUS SYSTEM BRAIN SPINAL CORD CENTRAL NERVOUS SYSTEM (CNS) AFFERENT EFFERENT NERVES NERVES EXTEROINTERORECEPTORS RECEPTORS EFFECTOR ORGANS PERIPHERAL NERVOUS SYSTEM SOMATIC SKELETAL MUSCLES AUTONOMIC SMOOTH AND CARDIAC MUSCLES AND GLANDS SENSORY INFORMATION TRAVELS TO THE BRAIN VIA SPECIALIZED PATHWAYS NOSE SMELL EYE VISION TONGUE TASTE EAR AUDITION SKIN SOMATIC NEOCORTEX LIMBIC CORTEX THALAMUS BRAIN STEM SPINAL CORD SENSORY MODALITIES AND RECEPTOR CELLS MODE WARMTH COLD PAIN RECEPTOR NERVE ENDINGS NERVE ENDINGS NAKEDNERVE ENDINGS NERVE ENDINGS JOINT MOVEMENT & POSITION MUSCLE NERVE ENDINGS LENGTH MUSCLE NERVE ENDINGS TENSION ORGAN SKIN SKIN SKIN VARIOUS MUSCLE SPINDLE GOLGI TENDON ORGAN GRADED VS ALL OR NONE • A RECEPTOR’S RESPONSE TO A STIMULUS IS GRADED • IF THRESHOLD IS EXCEEDED, THE ACTION POTENTIAL RESULTING IS ALL OR NONE SENSORY MODALITIES AND RECEPTOR CELLS MODE VISION HEARING MOTION SMELL TASTE RECEPTOR ORGAN RODS,CONES EYE HAIR CELLS EAR HAIR CELLS VESTIBULAR APPARATUS TOUCHPRESSURE NERVE ENDINGS OLIFACTORY NEURONS TASTE RECEPTOR CELLS OLIFACTORY MUCOUS MEMB. TASTE BUDS SKIN SENSORY TRANSDUCTION ADEQUATE STIMULUS MEMBRANE CONDUCTANCE CHANGE GENERATOR POTENTIAL ACTION POTENTIAL LOCALIZATION, DISTRIBUTION, AND ACUITY • CODING OF LOCATION DEPENDS ON RECEPTOR LOCATION • AREA COVERED BY RECEPTORS IN A SENSORY UNIT IS A RECEPTIVE FIELD • ACUITY DEPENDS ON THE DENSITY OF RECEPTORS SLOW PAIN • OCCURS AFTER A SECOND OR MORE • OFTEN ASSOCIATED WITH TISSUE DESTRUCTION • SUBJECTIVELY DESCRIBED AS BURNING, ACHING,THROBBING, NAUSEOUS, OR CHRONIC • C FIBERS WHICH SYNAPSE IN THE SUBSTANTIA GELITANOSA • FINAL PROJECTION IS THE FRONTAL CORTEX MECHANICAL, CHEMICAL AND THERMAL PAIN • FAST PAIN IS GENERALLY MECHANICAL OR THERMAL • SLOW PAIN CAN BE ALL THREE • CHEMICAL PAIN RECEPTORS: BRADYKININ, SEROTONIN, HISTAMINE, POTASSIUM IONS, ACIDS, ACETYL CHOLINE AND PROTEOLYTIC ENZYMES • PROSTAGLANDINS ENHANCE PAIN SENSATION BRAIN STRUCTURES AND PAIN • COMPLETE REMOVAL OF THE SENSORY CORTEX DOES NOT DESTROY THE ABILITY TO PERCIEVE PAIN • STIMULATION OF THE SENSORY CORTEX EVOKES A SENSATION OF PAIN PAIN CONTROL (ANALGESIA) • THE ANALGESIA SYSTEM • THE BRAIN’S OPIATE SYSTEM • INHIBITION OF PAIN BY TACTILE STIMULATION • TREATMENT OF PAIN BY ELECTRICAL STIMULATION • REFERED PAIN THE ANALGESIA SYSTEM • PREAQUEDUCTAL GRAY • RAPHE MAGNUS NUCLEUS • PAIN INHIBITORY COMPLEX IN DORSAL HORNS PAIN INHIBITORY COMPLEX: PRESYNAPTIC INHIBITION BRAIN STEM.NEURON ANTEROLATERAL PATHWAY INHIBITORY NEURON PAIN RECEPTOR + DORSAL HORN OF SPINAL CORD PAIN TRANSMISSION AND INHIBITION • SUBSTANCE P IS THE NEUROTRANSMITTER: BUILDS UP SLOWLY IN THE JUNCTION AND IS SLOWLY DESTROYED • PRESYNAPTIC INHIBITION BY INHIBITORY NEURON BLOCKS THE RELEASE OF SUBSTANCE P (ENKEPHALIN) THE BRAIN’S OPIATE SYSTEM • OPIATE RECEPTORS EXIST IN MANY CENTERS OF THE BRAIN, ESPECIALLY IN THE ANALGESIA SYSTEM • AMONG THE NATURAL SUBSTANCES WHICH ACTIVATE THESE RECEPTORS ARE: ENDORPHINS, ENKEPHALINS, AND MORPHINE INHIBITION OF PAIN BY TACTILE STIMULATION • STIMULATION OF LARGE SENSORY FIBERS FOR TACTILE SENSATION INHIBITS PAIN TRANSMISSION FOR SAME REGION • RUBBING OFTEN EASES PAIN • LINAMENTS, OIL OF CLOVE, ETC. • POSSIBLE EXPLANATION FOR ACUPUNCTURE? TREATMENT OF PAIN BY ELECTRICAL STIMULATION • STIMULATION OF LARGE SENSORY NERVES • ELECTRODES IN SKIN OR SPINAL IMPLANTS • INTRALAMINAR NUCLEUS OF THALAMUS REFERED PAIN • VISCERAL PAIN FIBERS SYNAPSE ON SAME SECONDARY NEURONS AS RECEIVE PAIN FIBERS FROM SKIN THE VISUAL SYSTEM D. C. MIKULECKY PROFESSOR OF PHYSIOLOGY AND FACULTY MENTORING PROGRAM THE VISUAL SYSTEM SENSES ELEECTROMAGNETIC RADIATION • ELECTROMAGNETIC RADIATION (EMR) SPANS THE ELECTROMAGNETIC SPECTRUM (EMS) • FROM RADIO WAVES (VERY LONG) TO RADIATION (VERY SHORT) • VISIBLE LIGHT IS A SMALL PORTION OF THE SPECTRUM • PHOTONS OF LIGHT INTERACT WITH MATTER ANATOMICAL ORGANIZATION • THE EYE • CORNEA AND LENS: BEND LIGHT RAYS AND FOCUS THEM ON THE RETINA • CILLIARY MUSCLES LOSSEN OR TIGHTEN TO ADJUST LENS THICKNESS • RETINA: SITE OF PHOTORECEPTORS • FOVEA: MOST SENSITVE PART OF RETINA TEAR DUCT AND DRAINAGE CANAL PUPIL IRIS SCLERA STRUCTURE OF THE EYE SUSPENSORY LIGAMENT CILIARY BODY CONJUNCTIVA IRIS PUPIL EXTERNAL EYE MUSCLE CHOROID RETINA SCLERA FOVEA LENS CORNEA AQUEOUS HUMOR VITREOUS HUMOR OPTIC NERVE OPTIC DISC BLOOD VESSELS THE PHOTORECEPTORS • RODS: CYLLINDRICALLY SHAPED- BROAD RANGE OF WAVELENGTHS, NIGHT • CONES: CONICALLY SHAPED-NARROW WAVELENGTH RANGE, COLOR BEFORE A PHOTON ARRIVES MEMBRANE POLARIZED NORMALLY AFTER A PHOTON ARRIVES •RHODOPSIN ABSORBS PHOTON AND CHANGES SHAPE •A SEQUENCE OF BIOCHEMICAL STEPS •MEMBRANE HYPERPOLARIZED PATHWAYS FOR VISUAL INFORMATION • OPTIC NERVE (GANGLION CELLS FROM RETINA) • LEAVES THROUGH “BLIND SPOT” • LATERAL GENICULATE NUCLEUS: PROJECTS TO CORTEX • PRIMARY VISUAL CORTEX VISUAL ORIENTATION COLUMNS • CELLS IN VARIOUS COLUMNS OF CORTEX RESPOND TO DIFFERENT ORIENTATIONS • THESE DEVELOP DURING THE EARLY VISUAL EXPERIENCES OF YOUNG ANIMALS COLOR VISION • TRICHROMATIC: RED, BLUE, GREEN • PARVOCELLULAR NEURONS CARRY INFORMATION • DIFFERENT CELL TYPES • COLOR CONTRAST THREE KINDS OF CONES • RED, BLUE, AND GREEN • CONNECT TO SMALL GANGLION CELLS • TRANSMIT COLOR INFORMATION TO PARVOCELLULAR NEURONS IN LGN COLOR NEURONS • BROAD BAND: SINGLE COLOR, + INSIDE, OUT • SINGLE - OPPONENT: EXITED BY ONE COLOR IN CENTER, INHIBITED WHEN ANOTHER COLOR IN PERIPHERY • DOUBLE OPPONENT: OPPOSING COLORS IN BOTH CENTER AND PERIPHERY • ANNULAR FIELDS OVERLAP TO RECTANGULAR IN CORTEX LENS DEFECTS • FOCUSING IN FRONT OF RETINA • NEARSIGHTEDNESS (MYOPIA) • USUALLY DUE TO WEAK CILIARY MUSCLES • FOCUSING BEHIND THE RETINA • FARSIGHTEDNESS(HYPEROPIA) • LENS TOO STIFF (AGING) NEARSIGHTEDNESS (MYOPIA) UNCORRECTED CORRECTED FARSIGHTEDNESS (HYPEROPIA) UNCORRECTED CORRECTED VISUAL FIELD DEFECTS • OPTIC NERVE:VISUAL FIELD ON SAME SIDE • OPTIC CHIASM:OUTER HALF OF BOTH VISUAL FIELDS • OPTIC TRACT: OPPOSITE HALF IN BOTH VISUAL FIELDS • OPTIC RADIATIONS:LOWER OR UPPER QUADRANT ON OPPOSITE SIDE THE AUDITORY SYSTEM AND THE CHEMICAL SENSES D. C. MIKULECKY PROFESSOR OF PHYSIOLOGY AND FACULTY MENTORING PROGRAM THE NATURE OF SOUND • COMPRESSION AND RARIFICATION OF AIR • WAVES OF HIGH AND LOW PRESSURE • TRANSMIT MECHANICAL FORCES CHARACTERISTICS OF A PRESSURE WAVE A T = WAVELENGTH A = AMPLITUDE f = 1/T FREQUENCY ANATOMY OF THE EAR • OUTER EAR • MIDDLE EAR • INNER EAR OUTER EAR • ACTS TO FOCUS SOUND WAVES ON THE TYMPANIC MEMBRANE • SHAPED LIKE A SOUND CONE OUTER EAR PINNA CANAL MIDDLE EAR • THREE BONES LINK TYMPANIC MEMBRANE TO OVAL WINDOW • VIBRATIONS TRANSMITTED MECHANICALLY MIDDLE EAR SOUND WAVE IN EAR CANAL TYMPANIC MEMBRANE BONES OF MIDDLE EAR COCHLEAR FLUID OVAL WINDOW INNER EAR • SITE OF TRANSDUCTION • VIBRATION OF COCHLEAR FLUID CAUSES BASILAR MEMBRANE TO VIBRATE • HAIR CELLS ARE DEFORMED • AUDITORY NERVE BECOMES EXCITED AS HAIR CELLS DEPOLARIZE INNER EAR COCHLEA OVAL WINDOW STRUCTURE OF THE COCHLEA OVAL WINDOW SCALA VESTIBULI COCHLEAR DUCT SCALA TYPANI ROUND WINDOW STRUCTURE OF COCHLEAR DUCT TECTORIAL MEMBRANE ORGAN OF CORTI BASILAR MEMBRANE TRANSDUCTION MECHANISM TECTORIAL MEMBRANE STATIONARY STEROCILIA HAIR CELLS AUDITORY NERVE BASILAR MEMBRANE…..VIBRATES TRANSDUCTION MECHANISM TECTORIAL MEMBRANE STATIONARY STEROCILIA BEND AUDITORY NERVE HAIR CELLS BASILAR MEMBRANE…..VIBRATES FREQUENCY DISCRIMINATION: LOCALIZATION OF DISPLACEMENT OF BASILAR MEMBRANE BASE APEX HIGH MID LOW AUDITORY PATHWAYS INFERIOR COLLICULUS SUPERIOR OLIVE VENTRAL COCHLEAR NUCLEUS COCHLEA VENTRAL COCHLEAR NUCLEUS MIDLINE AUDITORY PATHWAYS (CONT.) TEMPORAL CORTEX TEMPORAL CORTEX MEDIAL GENICULATE MEDIAL GENICULATE INFERIOR COLLICULUS INFERIOR COLLICULUS SUPERIOR OLIVE MIDLINE CHARACTERISTICS OF A PRESSURE WAVE A T = WAVELENGTH A = AMPLITUDE f = 1/T FREQUENCY PROPERTIES OF AUDITORY NERVE CELLS • EACH AUDITORY NERVE FIBER HAS AN OPTIMUM FREQUENCY • THIS TONOTOPIC ORGANIZATION ARISES FROM POSITION IN THE COCHLEA • TONIC AND PHASIC NEURONS IN EACH AREA • SOME RESPOND TO CHANGE IN FREQUENCY • SOME RESPOND TO CHANGE IN AMPLITUDE SOUND LOCALIZATION • INTERAURAL TIME DIFFERENCE • TIME DELAY BETWEEN TWO EARS • ALSO INTENSITY DIFFERENCES DISORDERS OF AUDITION • LOSS OF HAIR CELLS: FREQUENCY SPECIFIC • TINNITUS: RINGING • CONDUCTIVE:l DAMAGE TO MIDDLE EAR • CENTRAL: BRAIN TUMORS AND LESIONS THE VESTIBULAR APPARATUS • SEMICIRCULAR CANALS: HAIR CELLS SENSE MOTION • THREE COORDINATE PLANES: SUPERIOR, INFERIOR, AND HORIZONTAL • UTRICLE AND SACCULE DETECT LINEAR ACCELERATION IN HORIZONTAL AND VERTICLE PLANES THE VESTIBULAR APPARATUS: UTRICLE & SACCULUS ONE CANAL IN EACH COORDINATE PLANE UTRICLE & SACCULUS AMPULLA THE UTRICLE & SACCULUS OTOCONIA (CALCIUM CARBONATE CRYSTALS) NERVE CELLS OTOLITHIC MEMBRANEGELATINOUS LAYER HAIR CELLS THE UTRICLE & SACCULUS OTOCONIA (CALCIUM CARBONATE CRYSTALS) NERVE CELLS HEAD MOVEMENT OTOLITHIC MEMBRANEGELATINOUS LAYER HAIR CELLS THE VESTIBULAR APPARATUS: SEMICIRCULAR CANALS ONE CANAL IN EACH COORDINATE PLANE UTRICLE & SACCULUS AMPULLA THE AMPULLA NERVE CELLS HAIR CELLS THE AMPULLA MOVEMENT OF HEAD INERTIAL FLUID MOVEMENT NERVE CELLS FIRE HAIR CELLS BENT TASTE SENSATION • GUSTATORY RECEPTORS • GUSTATORY PATHWAYS GUSTATORY RECEPTORS • • • • • TASTE BUDS ON TONGUE LOCALIZED SWEET: TIP BITTER:BACK SOUR SIDES SALT: FRONT GUSTATORY PATHWAYS • VII, IX, X CRANIAL NERVES • TO GUSTATORY NUCLEUS IN BRAIN STEM • VPM NUCLEUS OF THALAMUS • GUSTATORY AREA OF NEOCORTEX • VIA LIMBIC SYSTEM TO HYPOTHALAMUS THE OLIFACTORY SYSTEM • RECEPTOR CELLS IN OLIFACTORY MUCOSAL MEMBRANE • AXONS CROSS CRIBIFORM PLATE AND TERMINATE ON MITRAL CELLS IN OLIFACTORY BULB-FORM OLIFACTORY TRACT • OLIFACTORY TRACT GOES TO LIMBIC SYSTEM AND TO ORBITOFRONTAL CORTEX • CLOSELY ASSOCIATED WITH EATING THE AUTONOMIC NERVOUS SYSTEM • TWO NEURON CHAINS • SYMPATHETIC • PARASYMATHETIC TWO NEURON CHAINS PRESYNAPTIC NEURON EFFECTOR SPINE ORGAN POSTSYNAPTIC NEURON SYMPATHETIC • • • • • GANGLION NEAR SPINE SHORT PREGANGLIONIC NEURONS LONG POSTGANGLIONIC NEURONS FLIGHT OR FIGHT POSTGANGLIONIC NEURONS ARE ADRENERGIC PARASYMPATHETIC • • • • • GANGLION NEAR EFFECTOR ORGAN LONG PREGANGLIONIC NEURONS SHORT POSTGANGLIONIC NEURONS “COUCH POTATO” POSTGANGLIONIC NEURONS ARE CHOLINERGIC EFFECTS OF ANS ORGAN HEART BLOOD VESSELS S + P - CONSTRICT(MOST ORGANS) DILATE (HEART DILATE (PENIS AND CLITORIS) ) AND SKELETAL BRONCHIOLES DILATE CONSTRICT PUPIL DIGESTION DILATE CONSTRICT INHIBIT ENHANCE
