Download - PHYSIOLOGY OF IMPULSE TRANSMISSION IN INSECTS SSNAIK TNAU

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


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


Neuron with a proximal axon & many distal

dendrites

Neuron with a single axon

Neuron with a proximal axon and a long distal dendrite

11

2

1

2

345

6

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


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


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

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)

Keep the farmers smile…… because we are scientific------------------------------------------

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