A nervous system is the main communicating, regulating, and controlling system of the organism. It is a complex system involved in the coordination of action and reaction to stimuli. The nervous system of the Periplaneta americana model is used for the study and analysis of pharmacological and neurobiological studies. The main segments of the central nervous system of Periplaneta americana are the CNS: Central Nervous System, PNS: Peripheral Nervous System, and SNS: Sympathetic Nervous System.
The nervous system of cockroaches
In cockroaches, the nervous system includes the segmented and fused ganglia linked on the ventral side by the longitudinal connectives. Three ganglia are present in the thorax region, while six ganglia are found in the abdomen region of the cockroaches. The major portion of the nervous system of cockroaches is found along the ventral portion of the body, while a bit of it lies in the head region. Because of this, cockroaches can survive for a week without their heads.The nervous system of the cockroaches is sub-categorised as; the Central nervous system, the Visceral or sympathetic nervous system, and the Peripheral nervous system.
The CNS of Periplaneta americana
CNS, or the central nervous system, is divided into several parts and is distributed throughout the body. The central nervous system of Periplaneta americana comprises the supra-oesophageal ganglion, suboesophageal ganglion, and the nerve cord. The interganglionic connectives pair the brain, thoracic, and abdominal ganglia to create a ventral nerve cord (VNC).
The supra-oesophageal ganglion or the brain has two lobes in its structure and is present in the head, between the bases of the antennae. It symbolises the brain and is formed by the fusion of the three pairs of ganglia and is concerned with sensory functions. The two connectives arising from the supra-oesophageal meet the suboesophageal ganglion.
The suboesophageal ganglion is formed by the fusion of the three pairs of the ganglion. It is situated in the head together with circumesophageal connectives, and supra-oesophageal ganglion forms the nerve rings. This part of the central nervous system is mainly responsible for controlling the movements of muscles, wings, legs, and mouthparts and hence is the principal motor centre.
Two double nerve cords arising from the suboesophageal ganglion region travel through the thorax and the abdomen region of the cockroach and run towards the posterior of the body. The third part of the central nervous system of the cockroach is a nerve cord that has large ganglia in the prothoracic, mesothoracic, and metathoracic segments of the thorax region and is called pro, meso, and metathoracic ganglia.
The nerve cord of the abdomen region lies in the 1st to 7th segment of the cockroach’s body. The two ganglia fuse except for the 7th to form the abdominal ganglion. The 7th abdominal ganglion is formed by the fusion of the three pairs of the ganglia and is the largest.
Components of the central nervous system
Supraesophageal Ganglion
It is also called the brain and is the ganglionic mass situated above the oesophagus in the anterior region. The constituent of the Supra Oesophageal Ganglion are:
- Protocerebrum: Characterise the integrated ganglia of the pre-antennal and the acorn region.
- Deutocerebrum: The chief part of the Supraesophageal Ganglion.
- Tritocerebrum: Rear portion of the Supraesophageal Ganglion or the brain and constitutes ganglia of an intercalary segment.
Suboesophageal Ganglion
In Arthropods, they are oval in shape and control the muscles and glands of the mouth region. They lie below the oesophagus in the head area and are surrounded by paired nerves.
The Ventral Nerve Cord
It includes ganglia present on the base of the thoracic and abdomen region. The components of the ventral nerve cord are:
- Thoracic ganglia: The first three ganglia of VNC in each thoracic segment are located separately.
- Abdominal ganglia: They are found in the stomach region and are six in number.
- Connective: They are longitudinal cords that join the preceding ganglia with the succeeding ganglia.
- Commissures: they connect the two ganglia and are transverse fibres.
Peripheral nervous system
The peripheral nervous system (PNS) and the Sympathetic or Visceral nervous system are other elements of the nervous system of cockroaches. The nerves of the ganglion area of the CNS distributed throughout the body comprise the cockroach’s PNS. The nerves of the optic, labour frontal, antennary, and suboesophageal ganglion supply and interlinks the nerves to the mouthparts of the arthropods.
The Sympathetic nervous system
Also called the Visceral nervous system is the autonomic nervous system that includes the ganglia and connections. It consists of the frontal ganglion, an oesophageal ganglion, and visceral ganglion. The sympathetic nervous system also includes the ganglia of occipital, frontal, preventricular, and ingluvial parts.
Conclusion
The nervous system of the cockroaches can be used for the study of toxins and neurobiological studies. The nervous system of the organism includes the Central nervous system (CNS), Peripheral Nervous System (PNS), and Sympathetic Nervous system. The Central nervous system in cockroaches is found in the segments of the body regions, and the ganglion is linked by the connectives.In cockroaches, the nervous system includes the segmented and fused ganglia linked on the ventral side by the longitudinal connectives. Three ganglia are present in the thorax region, while six ganglia are found in the abdomen region of the cockroaches.