As the complexity of the individuals, plants or animals increases the different cells and organs become separated from each other by greater distance.
It stores the previous experiences as memory that helps us to think and analyse our reactions.It conducts messages between different parts of the body.
The messages are transmitted in the form of electrical impulses along the fibres of the neurons.
Receptors are structures at the ends of the nerve fibres that collect the information to be conducted by the nerves.
The human nervous system can be divided into three main parts:Central nervous system, Peripheral nervous system, Autonomic nervous system.
The peripheral nervous system is made up of nerves that connect the different parts of the body (peripheral tissues) to the central nervous system.
It is made up of three lobes - anterior, middle and posterior. They secrete hormones in response to the secretion of neurohormones by the hypothalamus.
It is a gland that is prominent behind the breastbone in children.It gradually decreases in size in adults.
The adrenal glands are present on top of the kidneys and appear cap-like on top of each kidney. Each adrenal gland has two layers - outer cortex and inner medulla.
With increasing complexity, the organisms have had to develop means of control and coordination between the different parts of the body.