physiology of impulse transmission in insects ssnaik tnau
TRANSCRIPT
WEL COME
SSNAIKTNAU
TERM PAPER PRESENTATIONON
ENT 803ADVANCES IN INSECT PHYSILOGY
CPPS,TNAU,COIMBATORE-641 003
NAME :SABHAVAT SRINIVASNAIKID. NO: 2015 800 506YEAR: I Ph. D (2015)
DEPT.: AGRICULTURAL ENTOMOLOGY
INTRODUCTION
PART I
PART II
PART III
INDEX
INSECT NERVOUS SYSTEM (STRUCTURE)
IMPULSE TRANSMISSION (FUNCTION)
INTRODUCTION PART I
Protozoa to Chordata- highest evolved organism- human being A unicellular organism -single cell – functions- No coordination A 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, 2013
Structure Function
Physiology Nervous system Impulse transmission
INSECT NERVOUS SYSTEM
PART II-structure
INSECT NERVOUS SYSTEM
Soma/Cell body
Nucleus
Dendrite
AxonGlial cells-N. lamella
Protoplasm
Collateral
Arbo
risat
ions
Stimuli
Neurons – ganglion Strands of neurons-nerve
Branched projections of a neuron that conduct the impulses received from other neural cells to the cell body
Long 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 nm
ii) Gap junction -3.5 nm
(Direct transmission)
Post synaptic neuron
Pre synaptic neuron
SYNAPSEThe junction between the terminal of a neuron and either another neuron or a muscle or gland cell, over which nerve impulses pass
Electron lucent
Electron dense
Physical synapsesFunctional synapsesRetinula cell of fly =200 Physical synapse
Single to many cells/Among them one =functional
Chapman, 1998
GLIAL CELLS- “BLOOD BRAIN BARRIER CONCEPT”
Each neuron consist of glial cells
Synaptic contact occur where there
is no glial cells
Glial cells pass nutrient materials
to neurons
It reserves glycogen
Used 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 dendrite
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A. STRUCTURAL BASIS
INSECT NERVOUS SYSTEMB. FUNCTIONAL BASIS
Internuncial (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, Efferent neurons, monopolar, situated in the ganglia and monopolar, situated in the ganglia and conduct impulse from CNS to effector conduct impulse from CNS to effector organs like muscles and glandsorgans like muscles and glands
Afferent (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-systems
i. 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 SYSTEM
Formed 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 SYSTEM
3.Thoracic ganglia
4. 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
1. Stomodeal / stomatogastric Frontal ganglion and connected with aorta, foregut and midgut
2. Ventral visceral Associated with the ventral nerve cord
3. Caudal visceral
Associated with the posterior segments of abdomen and reproductive organs
INSECT NERVOUS SYSTEMiii. Peripheral Nervous Systemiii. Peripheral Nervous System
Sensory 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
Axon
Donnan equilibrium
Visual/ Chemical/ Mechanical
Sensory neuron
Environment
Insect
1. Axonic conduction……….
IMPULSE TRANSMISSION…
1. Axonic conduction1.Resting potential The state during which no nerve impulse is being
conducted although the neuron is capable of doing so
2. Action potential The 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
2. Synoptic transmission
Axonal-dendritic (axon to dendrite)
Axonal-somatic (axon to soma)
Axonal-axonal (axon to axon)
Location of synapses
Synaptotagmin
Synaptobrevin
Synap-25
Syntaxin
Proteins -Acetyl choline
dendritereceives information
cell bodycontains nucleus & organelles
axontransmits nerve impulse
axon terminaltransmits to next neuron
synapsejunction between two neurons
Direction of nerve im
pulse
INETARCTION OF DIFFREENT SYSTEMS
Please keep watch......
AXONIC TRANSMISISON
References• Chapman, 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 Srinivasnaik
ID.NO:2015800506I Ph. D (Agrl. Entomology)
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