7.THE NERVOUS SYSTEM

Neurons are similar in all animal vary in complexity .More complex organisms have  complex nervous systems and more neurons  enables faster  complex precise behaviour 

         ＴＨＥ  ＮＥＲＶＯＳ  ＳＹＳＴＥＭ  ＩＮ  ＶＥＲＴＥＢＲＡＴＥＳ

All invertebrates ,except ,sponges , have a nervous system, are three basic   types of systems in invertebrates :

 

Nerver nets : the neuron form a nerve net throughout the body transmite in all directions . Typically of cnidaria

Nerves rings: neurons  form a ring around the mouth .A nerve extend  from the ring into each arm .Typical of animals  with raidal simetrylike echinoderm

Ganglia : neuron are grouperd into each cluster called ganglia. Ganglia are connected by a nerve cord .

     𝗧𝗛𝗘 𝗡𝗘𝗥𝗩𝗢𝗨𝗦 𝗦𝗬𝗦𝗧𝗘 𝗜N 𝗜𝗡𝗩𝗘𝗥𝗧𝗘𝗕𝗥𝗔𝗧𝗘𝗦

The nerves systems in a vertebrate 

the periteral nervous system es has two parts :

The central nervous system