Illustrated · 2 min
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Why Do Living Things Need to Respond to the Environment?
If you're like me, you might get extremely nervous before taking a test. My heart starts to beat faster, I get jittery, and I feel sweaty. This is one of the ways in which my body responds to the environment. When you're scared or anxious, your body interprets that there is danger nearby. In response, we enter the fight or flight mode. The body circulates blood faster and we feel more alert. This gives us extra strength in case we need to fight whatever is coming or run away from it.
In general, every organism has some senses that help it respond to the environment. For humans it's sight, smell, taste, touch, and hearing. Not all organisms have all of these, and some have completely different senses. For example, sharks can sense electrical differences between water and other fish, which helps them find their food. Additionally, elephants can sense vibrations created by other elephants even ten miles away. This helps them communicate over long distances.
The delicious smell given off by pizza is a stimulus. The receptors in the nose of a lurking pug sense the stimulus and send information about it to the brain, or control center. Then, the brain decides how the pug should respond to the stimulus. The pug starts drooling as he prepares to devour the pizza. Image source: By Gabi Slizewska
The Reaction Chain
Responding to the environment begins with a stimulus. This is essentially anything that triggers a receptor for one of those senses. An example would be the receptors on our skin which sense a stimulus like temperature or pain. Then, information is sent to the nervous system, our control center, which decides how the body should respond. The response is called the effector. This could be shivering when you're cold in order to warm up or even just putting on a coat.
A stimulus can be external, like seeing something happening around you, but it can also be internal. For example, if you haven't eaten in a while, you start to feel hungry. Hunger is the internal stimulus which makes you eat.
So why is this interaction so important? It helps us avoid danger, find food, and communicate with people we know. It also helps us maintain homeostasis, a stable environment within the body. You would not be able to survive without the ability to respond to the environment.
