Year 1 · Senses, behaviour and coordination · Section 5.1

Sensing your surroundings

Sensing the environment

You use your senses to detect your surroundings. They respond to stimuli, such as light, smells and sound. A sense organ contains receptors sensitive to particular stimuli.

Sensory cells detect a stimulus and produce signals that lead to nerve impulses. These electrical signals travel along nerves to the brain, which processes them. For example, seeing or smelling chocolate allows you to recognise that it is nearby.

Sense organs

Your sense organs work together as a sensory system. Important examples and their stimuli are:

• Eyes: Detect light for vision.
• Ears: Detect sound for hearing; the inner ear also contains balance organs that detect head movement and position relative to gravity.
• Nose: Detects airborne scent molecules for smell.
• Tongue: Contains taste receptors responding to dissolved substances, producing tastes such as sweet or sour.
• Skin: Contains receptors responding to warmth, cold, pressure and light touch. Touch receptors help you detect textures and softness.

The body also has pain receptors: sensory nerve endings that detect potentially damaging conditions. They occur in many tissues, including internal organs.