NERVOUS SYSTEM OF PERIPLANETA AMERICANA


NRVOUS SYSTEM OF PERIPLANETA AMERICANA

The nervous system of periplaneta consists ofp.nervous system

Central nervous system ,

Peripheral nervous system and

Autonomous nervous system.

1)   CENTRAL NERVOUS SYSTEM:

The central nervous system of periplanata consists of a nerve ring ,  and

Double ventral nerve cord.

NERVE RING :-

The nerve ring is present around the oesophagus. It is formed by the brain , sub-oesophageal ganglion and circum-oesophageal connectives.

  1. Brain :
    1. Brain is the spra-oesophageal ganglion. It lies above the oesophagus.
    2. Brain has three lobes. They are protocerebrum , deutocerebrum  and tritocerebrum.
    3. The protocerebrum receives sensory impulses from the compound eyes throughoptic nerves; Deutocerebrum receives sensory impulses from antennae through antennal nerves; and tritocerebrum receives sensory impulses from the labrum. Hence brain is principally sensory in nature.
  2. Sub-oesophageal ganglion :-
    1. Sub-oesophageal ganglion lies below the oesophagus.
    2. It controls the movement of mouthparts, legs and wings. Hence it is the principal motor center.
  3. Circum-oesophageal connectives :-

A pair of circum-oesophageal connectives is present around the oesophagus, connecting the tritocerebrum with the sub-oesophageal ganglion.

  VENTRAL NERVE CORD :-

  1. The two ventral nerve cords are solid and ganglionated.
  2. They arise from the sub-oesophageal ganglion and extend upto the 7th abdominal segment.
  3. Two nerve cords are connected by a ganglion in each segment .
  4. In periplaneta total nine ganglion are present on ventral nerve cords. Three are thoracic ganglion and six are abdominal ganglion.
  5. Three thoracic ganglia are present , one in each thoracic segment.
  6. The first to the fourth abdominal segments have one abdominal ganglion each.
  7. The fifth abdominal segment has no ganglion.
  8. The serially 5th abdominal ganglion is present in the sixth segment and the 6th  abdominal ganglion is preent in the seventh segment.
  9. The last or the sixth abdominal ganglion is the largest of all the abdominal ganglia. It is formed by the fusion of the ganglion of the 7th, 8th , 9th and 10th abdominal segments.

2)   PERIPHERAL NERVOUS SYSTEM:-

  1. The peripheral nervous system consists of nerves that arise or go to different ganglia.
  2. Brain is the chief sensory organ. It receives a pair of optic nerves, from the compound eyes , a pair of antennal neves fron the antennae and a pair of labral nerves , from the labrum.
  3. Sub-oesophageal ganglion gives off motor nerves to the mandibles, maxillae, labium, wings and legs. It is the principal motor centre in the body.
  4. Thoracic ganglia supply nerves to the parts of their respective segments.
  5. Meta thoracic ganglia send nerves to the first abdominal segment also.
  6. Nerves from the first four  abdominal gangia supply to the  organs of the segments 2-6 serially.
  7. The fifth ganglion present in the 6th abdominal segment innervates the organs of that segments.
  8. The sixth ganglion present in the 7th abdominal segment innervates the all organs present in 7th – 10th abdominal segments. The organs include the reproductive organs , copulatory appendages besides anal cerci.

3)   AUTONOMOUS NERVOUS SYSTEM :-

  1. This system is also called stomogastric nervous system or visceral nervous system.
  2. It controls the visceral organs , particularly the muscles of the alimentary canal and the heart.
  3. The autonomous nervous system includes four ganglia, a frontal ganglion , a hypocerebral ganglion, a visceral ganglion and a proventricular ganglion.
  4. A frontal ganglion on the dorsal wallof the pharynx, in front of the brain. Hypocerebral ganglion is above the oesophagus behind the brain. A visceral ganglion is on the wall of the crop  and a proventricular ganglion is on thegizzard.
  5. These ganglia contain the somata of the post ganglionic motor neurons. Pregnglionic motor neurons of tritocerebrum go to the frontal ganglion as labor-frontal andfrontal nerve.
  6. Frontal ganglion is connected to the hypocerebral ganglion by a recurrent nerve.
  7. Hypocerebral ganglion is connected to the  visceral ganglion and in turn the visceral  ganglion is connected to the proventricular ganglion.
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About balarangaiahnarapuram

TEACHER M.Sc in ZOOLOGY M.Sc in PSYCHOLOGY B.Ed
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