Insects communicate with the external environment through the nervous system. The nervous system connects a wide variety of sensors and reactors on the surface of the body wall and inside the body. The nervous system of insects is also the information communication system and the important overall control system of insects 1. Central nervous system: the center of sensation, contact and motor coordination, the central nervous system includes the brain and the ventral nerve cord, which is the core part of the insect nervous system.
2. Sympathetic nervous system: controls feeding, respiration, reproduction and internal organ activity. It includes the oral sympathetic nervous system that controls the digestive tract, the median nerve that controls the valve and dorsal blood vessels and the abdominal terminal ganglion that controls the reproductive organs and hindgut.
3. Peripheral nervous system: collects stimuli from the sensory organs to the central nervous system, transmits signals from the central nervous system to the reactors, and includes all nerves emanating from the central system. Basic structure . Neurons: functional cells that transmit information. Neurons, also called nerve cells, are the basic units of the nervous system. Insect neurons consist of three parts: 1 nerve cell body, 1 or more dendrites 1 axon.
Glial cells: supply nutrients and stabilize the internal environment for nerve cells, are an important part of the ganglion and form the nerve sheath.
Ganglion: neurons, glial cells and non-cellular tissue formed by the ovoid or polygonal structure; the outer layer is non-cellular tissue of the peripheral membrane and glial cell layer composed of protective and nutritional function of the nerve sheath. Nerve conduction mechanism
The basis of nerve activity is the transmembrane potential of the nerve cell, and the external stimulus makes the permeability of the membrane change, causing the occurrence of action potential. The conduction mechanism of nerves is categorized into axonal conduction and synaptic conduction.
Axonal conduction: the axon is the starting site of nerve impulse, it is in the starting segment of the axon, along the axon membrane for nerve conduction mode.
The main function of the axon is to transmit nerve impulses from the cell body to other neurons or effector cells.
Synaptic conduction: synapses are connection points between neurons, between nerves and muscles, and between nerves and glands, and are the contact areas for nerve conduction.
The synapse consists of three parts: the presynaptic membrane, the postsynaptic membrane and the synaptic gap. Synaptic conduction is the conduction of nerve impulses between neurons through the synaptic gap. Synapses are divided into two types: electrical and chemical synapses
The characteristics of electrical synapses: the gap is extremely small, the nerve impulse passes through directly, the speed is fast, and the conduction has no direction.
Chemical synapse characteristics: conduction is directional, slow, rely on transmitter action on the back membrane receptors for excitation conduction.
Process of synaptic transmission: after synaptic transmission, acetylcholine is hydrolyzed by acetylcholinesterase on the membrane, and the hydrolyzed product is absorbed by the presynaptic membrane, and then synthesized into acetylcholine under the action of choline acetylase, and then stored in vesicles, in preparation for the next transmission.