Insect Nervous System PDF

GENERAL PHYSIOLOGY AND TOXICOLOGY l AG-MC312 1st Semester, 2024-2025 l BSA 3-Animal Science, Agronomy, Crop Protection & Horticulture IIE. The nervous system of insects ILO l Identify the insect metabolic systems as to its parts/structures and functions on insect’s various life process...

GENERAL PHYSIOLOGY AND TOXICOLOGY l AG-MC312 1st Semester, 2024-2025 l BSA 3-Animal Science, Agronomy, Crop Protection & Horticulture IIE. The nervous system of insects ILO l Identify the insect metabolic systems as to its parts/structures and functions on insect’s various life processes MARIA LIMA D. PASCUAL Professor, Dept. of Agriculture & Food Science (DAFS) College of Agriculture, Food Science, Agribusiness and Development Communications (CAFBC) CTU-Barili Campus Nervous system of insects Nervous system of insects Nervous system - is a network of specialized cells called neurons that serve as “information Neuron highway” within the body Anatomy of nervous system Neuron Central NS Visceral NS - is the structural & functional unit of Peripheral NS nervous system Impulse Neurons communicate with each other thru transmission specialized structures called synapses and chemicals (eg. neurotransmitters) Nervous system of insects Parts of neuron Nervous system 1. Cell body Neuron - known also as perikaryon/ Anatomy of soma that contains the nucleus nervous system Central NS 2. Dendrite Visceral NS - receives the stimulus & bring Peripheral NS information to the cell body Impulse transmission 3. Axon - take information away from the body Nervous system of insects Some terms Nervous system Collaterals - branches of axon Axon terminal – terminal of axon Neuron Neurocyte – body of neuron Anatomy of Neuropile – mass of axon nervous system Synapse Central NS - special junctions where individual Visceral NS nerve cells connect with one another Peripheral NS - when a nerve impulse reaches the Impulse synapse, it releases a chemical transmission messenger (neurotransmitter substance) that diffuses across the synapse and triggers a new impulse in the dendrite(s) of one or more connecting neurons Nervous system of insects Classification of neurons A. Based on number of extensions Nervous system 1. Unipolar - single axon without dendrites; Neuron has one projection extending from the soma (ex. CNS) Anatomy of nervous system 2. Bipolar - have either collateral or dendrite Central NS in addition to axon; two projections Visceral NS extending from the cell body; typical of Peripheral NS sensory neuron (ex. PNS) Impulse transmission 3. Multipolar - neurons with axon having several collaterals and dendrites; many projection extending from the soma but only one axon (ex. found in the ganglia of the nervous system) Nervous system of insects Classification of neurons B. Based on functions Nervous system 1. Afferent (sensory) Neuron - conducts impulses from sensory organs to cns Anatomy of nervous system 2. Efferent (motor) Central NS - conducts impulses away from Visceral NS the cns & stimulate responses Peripheral NS in muscles & glands Impulse transmission 3. Internuncial (association) - interconnective neurons that acts as a link between sensory and motor neurons; form connections between afferent and efferent neurons and conduct signals within the cns Nervous system of insects Some more terms Nerve Nervous system - is a bundle of dendrites or axons Neuron that serve the same part of the Anatomy of body nervous system Ganglia (ganglion) Central NS Visceral NS - is a dense cluster of neurons; Peripheral NS - forms a connecting link between sense Impulse organs & effector organs of insects; transmission - is specially form for the rapid conduction of impulses - number of ganglia vary with different insects but in typical insects there are 13 ganglia Nervous system of insects Some more terms Nervous system Commissures Neuron - are transverse fiber that Anatomy of connects each ganglia in nervous system Central NS each segment Visceral NS Peripheral NS Impulse Connectives transmission - longitudinal fiber that connects intersegmental ganglia Nervous system of insects Anatomy of nervous system Nervous system Central NS Visceral/Sympathetic NS Peripheral NS Neuron Anatomy of nervous system ▪ Brain/cerebral/ ▪ Esophageal/stomadeal/ Central NS supraesophageal stomagastric NS Visceral NS ganglion Peripheral NS ▪ Ventral sympathetic NS Impulse ▪ Subesophageal ▪ Caudal sympathetic NS transmission ganglion ▪ Ventral nerve cord Nervous system of insects Central nervous system a. Brain/cerebral/cephalic/supra-esophageal ganglion Nervous system - consist of a series of ganglia (brain + ventral Neuron nerve cord) that supply nerves to successive Anatomy of segments of the body nervous system ▪ Protocerebrum - first pair of ganglia associated Central NS with vision; they innervate the compound eyes & Visceral NS ocelli Peripheral NS ▪ Deutocerebrum - second pair of ganglia process Impulse sensory information collected by the antennae transmission ▪ Tritocerebrum - third pair of ganglia that innervate the labrum and integrate sensory inputs from proto- & deutocerebrum; also link the brain with the rest of the ventral nerve cord & the stomadeal NS that controls the internal organs Nervous system of insects Central nervous system Nervous system b. Sub-esophageal ganglion - located just below the Neuron esophagus and formed by Anatomy of the fusion of maxillae, nervous system mandibles, labium & Central NS hypopharynx Visceral NS Peripheral NS c. Ventral nerve cord Impulse - present in the thorax and transmission abdomen; innervates the activity of thoracic and abdominal ganglia Source: https://www.youtube.com/watch?v=YgFksx MJPyI&t=2s Nervous system of insects Visceral/sympathetic NS Nervous system - consist of three separate systems: Neuron a. Stomodeal/stomatogastric - frontal ganglion & connected with aorta, foregut and Anatomy of nervous system midgut Central NS Visceral NS b. Ventral visceral NS Peripheral NS - associated with the ventral cord Impulse transmission c. Caudal visceral NS - associated with the posterior segments of abdomen & reproductive organs Nervous system of insects Stomodeal/stomagastric NS - innervates the internal organs of insects Nervous system Frontal ganglion (unpaired) Neuron - consist of esophageal, frontal, ingluvial & hypocerebral ganglia; innervates the activity of Anatomy of foregut, midgut and heart nervous system Central NS Hypocerebral ganglion Visceral NS - link the frontal nerve to the anterior wall of Peripheral NS the esophagus; innervates the pharynx & muscles associated with swallowing Impulse - a gastric nerve that arises from the hypocerebral transmission ganglion and run posteriorly in the abdomen that innervate the hindgut Ingluvial ganglia (paired) - a recurrent nerve of the foregut that connects the frontal ganglion with hypocerebral ganglion; innervates the heart, corpora cardiaca, & portions of the foregut Nervous system of insects Visceral/sympathetic NS Nervous system a. Esophageal sympathetic/ stomadeal/stomatogastric Neuron Anatomy of b. Ventral sympathetic NS nervous system - located in thorax and abdomen Central NS which innervates the activity of Visceral NS Peripheral NS spiracles Impulse c. Caudal sympathetic NS transmission - innervates the anus, internal and external genitalia and sensory receptors (as cerci) Nervous system of insects Peripheral NS Nervous system - all sensory neurons; Neuron - not bundled in Anatomy of ganglia; nervous system - located in integument Central NS that innervates the Visceral NS activity of sense Peripheral NS organs, muscles and Impulse endocrine glands transmission Nervous system of insects Impulse transmission - a nerve impulse is an electric current that travels along Nervous system dendrites or axon due ions moving through voltage gated Neuron channels in the neurons plasma membrane Anatomy of 1. Axonic transmission nervous system Central NS - transfer of impulses from the axon Visceral NS Peripheral NS 2. Synaptic transmission Impulse - transfer of impulses across the transmission neuron through synaptic gap (junction between the axonic end of one neuron and dendrite end of another neuron) Nervous system of insects Neurotransmitters Nervous system Neurotransmitters - chemicals responsible for the transfer of impulses Neuron across the neuron Anatomy of Acetylcholine (ACh) - excitatory in CNS nervous system Glutamate - excitatory at muscle Central NS Gamma aminobutyric acid (GABA) – inhibitor Visceral NS Peripheral NS Neuromodulators - chemicals which modify the activity of neurotransmitters; Impulse sometimes in the presynaptic or in the post-synaptic area transmission Octopamine Protolin Serotonin Source: https://www.youtube.com/watc h?v=pNCMz2HzKRg&t=28s Contents The circulatory system The hemolymph Thank you. The hemocoel Dorsal vessel Circulation