2.1 Responding to Change

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2.1 Responding to Change

An animal’s response to a stimulus is coordinated by their central nervous system (CNS).

Receptors are groups of specialised cells that can detect changes in the environment called stimuli.

Receptors located in sense organs ---- Stimuli

·         ·         Eyes (sight) --- Light

·         ·         Ears (sound) --- Sound

·         ·         Mouth (taste) --- Chemicals

·         ·         Skin (touch) --- Preasure/Temperature

·         ·         Nose (smell) --- Chemicals

The CNS consists of the brain and spinal cord. When a receptor is stimulated it sends a signal along the nerve cells, also called neurones, to the brain. The brain then coordinates the response.

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2.1 Responding to Change

(http://www.mstrust.org.uk/information/publications/msexplained/images/cns.gif) Sensory Neurons carry impulses from receptors to CNS. Motor Neuron carry impluses from CNS to effector organs(muscles/glands). The muscles respond by contracting. Glands respond by secreating (releasing) chemicals.

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