PHYSIOLOGY OF IMPULSE TRANSMISSION IN INSECTS SSNAIK TNAU

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  • WEL COME SSNAIKTNAU

  • TERM PAPER PRESENTATIONON

    ENT 803ADVANCES IN INSECT PHYSILOGYCPPS,TNAU,COIMBATORE-641 003

    NAME :SABHAVAT SRINIVASNAIKID. NO: 2015 800 506YEAR: I Ph. D (2015)DEPT.: AGRICULTURAL ENTOMOLOGY

  • INTRODUCTION

    PART IPART IIPART III

    INDEXINSECT NERVOUS SYSTEM (STRUCTURE) IMPULSE TRANSMISSION (FUNCTION)

  • INTRODUCTION PART I

  • Protozoa to Chordata- highest evolved organism- human being A unicellular organism -single cell functions- No coordinationA multicellular organism-well organised mass of matter Contains different chemical compounds It performs chemical activities and physical activities Charged organism state of equilibrium with its environment.Coordination- Insect nervous system Nervous system- poorly insulated current system Introduction (Pant and Ghai, 1981)

  • Introduction Living organism-RF Chapman, 1998 and J. Simpson, 2013Structure Function

    Physiology Nervous system

    Impulse transmission

  • INSECT NERVOUS SYSTEM PART II-structure

  • INSECT NERVOUS SYSTEMSoma/Cell body Nucleus Dendrite AxonGlial cells-N. lamellaProtoplasm Collateral

    Arborisations Stimuli

    Neurons ganglion Strands of neurons-nerve

    Branched projections of a neuron that conduct the impulses received from other neural cells to the cell bodyLong slender projection of a nerve cell that conducts nerve impaulses from the cell body to other neurons, muscles, and organs

  • Introduction i) Synaptic cleft (Chemical transmission)Vesicles

    20-25 nmii) Gap junction -3.5 nm(Direct transmission)Post synaptic neuronPre synaptic neuronSYNAPSEThe junction between the terminal of a neuron and either another neuron or a muscle or gland cell, over which nerve impulses passElectron lucent Electron dense

    Physical synapsesFunctional synapsesRetinula cell of fly =200 Physical synapseSingle to many cells/Among them one =functional

  • Chapman, 1998GLIAL CELLS- BLOOD BRAIN BARRIER CONCEPT Each neuron consist of glial cells Synaptic contact occur where there is no glial cellsGlial cells pass nutrient materials to neuronsIt reserves glycogenUsed during development of CNS Used in making repairs

  • INSECT NERVOUS SYSTEM Neuron with a proximal axon & many distal dendrites Neuron with a single axon Neuron with a proximal axon and a long distal dendrite112123456A. STRUCTURAL BASIS

  • INSECT NERVOUS SYSTEMB. FUNCTIONAL BASISInternuncial (association) neurons : Unipolar cells (often with several collaterals and/or branching axons) (conduct signals within CNS)Motor neuron: conducts impulse from CNS to effector organs-Efferent neurons, monopolar, situated in the ganglia and conduct impulse from CNS to effector organs like muscles and glandsAfferent (sensory) neurons : Bipolar or multipolar cells have dendrites - associated with sense organs or receptors (carry information towards CNS).

  • INSECT NERVOUS SYSTEMNervous system divided in to three major sub-systemsi. Central nervous system (CNS) ii. Visceral nervous system (VNS) iii. Peripheral nervous system (PNS)

  • INSECT NERVOUS SYSTEMi) Central nervous system (CNS) Contains double series of nerve centers (ganglia).These ganglia are connected by longitudinal tracts of nerve fibers called connectives. Transverse tracts of nerve fibers called commissures

  • INSECT NERVOUS SYSTEMFormed by the fusion of first three cephalic neuromeres a) Protocerebrum Large, innervate compound eyes and ocellib) Deutocerebrum:Found beneath protocerebrum, innervate antennae c) Tritocerebrum: Bilobed, innervate labrum Main sensory centre controlling insect behaviour 1. Brain

  • INSECT NERVOUS SYSTEM3.Thoracic ganglia4. Abdominal ganglia Median chain of segmental ganglia beneath oesophagus Formed by the last three cephalic neuromeres which innervate mandible, maxillae and labium. 2. Sub oesophageal ganglia Three pairs found in the respective thoracic segments, largest ganglia, innervate legs and muscles.

  • House flySilverfish

  • INSECT NERVOUS SYSTEMii. Visceral nervous system/sympathetic consists of three separate systems Stomodeal / stomatogastric Frontal ganglion and connected with aorta, foregut and midgutVentral visceral Associated with the ventral nerve cordCaudal visceral Associated with the posterior segments of abdomen and reproductive organs

  • INSECT NERVOUS SYSTEMiii. Peripheral Nervous SystemSensory neurons of the cuticular sensory structures (the sense organs) that receive mechanical, chemical, thermal or visual stimuli from an environment

    All the motor neuron axons that radiate to the muscles from the ganglia of the CNS and visceral nervous system

  • IMPULSE TRANSMISSION PART III-Function/Physiology

  • IMPULSE TRANSMISSION A nerve impulse is an electric current that travels along dendrites or axon due to ions moving through voltage gated channels in the neurons plasma membraneTypes 1. Axonic conduction2. Synaptic conduction

  • IMPULSE TRANSMISSION 1. Axonic conduction

    Positive ions Negative ions Sodium channels AxonDonnan equilibrium

  • Visual/ Chemical/ Mechanical

    Sensory neuron

    Environment Insect 1. Axonic conduction.

  • IMPULSE TRANSMISSION 1. Axonic conduction1.Resting potentialThe state during which no nerve impulse is being conducted although the neuron is capable of doing so 2. Action potentialThe state during which the neuron is actively involved in conducting a nerve impulse 3. Recovery potential The state during which the neuron is unable to conduct a nerve impulse since it must recover from the last impulse

  • Resting neuron A charge difference is maintained Na+ is pumped out and K+ is pumped in So exterior become (+) and interior become () This is called resting membrane potential Restoring neuron K+ channel opens ( Na K ATP ase)K+ ions goes out So again interior become () and exterior become (+)1. Axonic conduction

  • 2. Synoptic transmission

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  • 2. Synoptic transmission

  • Axonal-dendritic (axon to dendrite) Axonal-somatic (axon to soma) Axonal-axonal (axon to axon)Location of synapses Synaptotagmin SynaptobrevinSynap-25Syntaxin Proteins -Acetyl choline

  • Direction of nerve impulse

  • INETARCTION OF DIFFREENT SYSTEMS

  • Please keep watch...... AXONIC TRANSMISISON

  • ReferencesChapman, R. F. 1998. The insects: structure and function. Cambridge university press.N. C. Pant and Miss Swaraj Ghai. 1981. Insect physiology and anatomy, ICAR, New Delhi Internet

  • Thank You Presented bySabhavat SrinivasnaikID.NO:2015800506I Ph. D (Agrl. Entomology) Keep the farmers smile because we are scientific------------------------------------------

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