Human Neural System

The neural system of all animals is composed of highly specialised cells called neurons, which can detect, receive and transmit different kinds of stimuli.

The neural organisation is very simple in lower invertebrates. For example, in Hydra it is composed of network of neurons.

Neural system is better organised in insects, where a brain is present along with number of ganglia and neural tissues.

The vertebrates have a more developed neural system.

Human Neural System Human neural system is divided into two parts:

(i) The Central Nervous System (CNS)

(ii) The Peripheral Nervous System (PNS)

The CNS includes the brain and the spinal cord and is the site of information processing and control.

The PNS comprises of all the nerves of the body associated with CNS (brain and spinal cord).

The nerve fibres of the PNS are of two types

(a) Afferent Fibres (b) Efferent Fibres

Afferent fibres transmit impulses from tissues/organs to the CNS and the efferent fibres transmit regulatory impulses from the CNS to concerned peripheral tissues/organs.

PNS is divided into two divisions called somatic neural system and autonomic nervous system.

Somatic neural system relays impulses from the CNS to skeletal muscles while the autonomic neural system transmits impulses from CNS to the involuntary organs and smooth muscles of the body.

The autonomic neural system is further classified into sympathetic neural system and parasympathetic neural system.