Any changes in the environment affect the living organisms and this detectable change in human or animals bodies is termed as’ Stimulus.’ For example, when you feel cold you wear warm clothes because you felt the stimulation of freezing weather on your skin.
The changes that an organism does on stimulation are called ‘Response.’
All living beings can touch, smell, taste, and feel the external environmental conditions because they have a Nervous system that acts rapidly to any internal and external changes. Therefore, animals and humans respond quickly when they undergo sudden stimulations.
Though Stimulus can also happen to non-living things, they cannot respond as they have not had a nervous system to feel and react.
Trees, herbs, bushes, and other plants can respond, but they reflect it in the behavior of growth.
Stimulus is a singular term, and we use the word ‘Stimuli’ for plural terms.
The Nervous System is made up of complex nerves, neurons, the spinal cord, and cells that send electrochemical signals to bring on any external changes to the body and the environment. It helps in the instant response to stimuli.
Endocrine System consists of a collection of glands that performs internal functions such as metabolism, digestion, breathing, reproduction and many more. It responds slower in the terms of development, hormonal changes, and external body growth.