The human body has two communication systems that allow us to respond to any changes in our environment.
The nervous system uses nerve impulses (electrical impulses) to react quickly to a stimulus.
The hormonal system uses hormones to react slowly to a stimulus.
|Nervous system||Hormonal system|
|Nature of response||Electrical impulses||Hormones/chemicals that travel in blood|
The nervous system
The brain and spinal cord form the central nervous system (CNS). The CNS controls and coordinates responses between receptors and effectors.
- Stimuli are changes in our environment that we respond to and are detected by receptors.
- Different receptors are sensitive to different stimuli (e.g. receptors in the eye are sensitive to light).
- A nerve cell/neurone carries information in the form of nerve impulses from the receptor to the coordinator.
- The coordinator – brain or spinal cord – determines whether or not to respond to the stimulus.
- A neurone carries information from the coordinator to an effector.
- An effector is a muscle or gland that can bring about a response.