The nervous system of earthworm is divided into 3 parts: (i) Central nervous system, (ii) Peripheral nervous system, (iii) Sympathetic nervous system. (i) Central Nervous System: It consists of a bilobed brain or cerebral ganglia, sub-pharyngeal ganglia, circum- pharyngeal connectives and a ventral nerve cord (Fig. 1.1). The brain is present on the dorsal side of alimentary canal in the [...]
All the nerve fibres carry information in the form of nerve impulse. Nerve impulse is the sum total of physical and chemical disturbances created by a stimulus (electrical, chemical or mechanical) in a neuron or nerve fibre which result in the movement of a wave along the nerve fibre. The nerve fibre or axon is like a cylinder, the interior [...]
Two types of autonomic nervous system are: 1. Sympathetic Nervous System 2. Parasympathetic Nervous System. The autonomic nervous system is responsible for the maintenance and regulation of internal environment by controlling automatic activities of the internal body organs. It regulates the functions of those organs which are not under the control of will (involuntary functions) such as circulatory, respiratory systems, [...]