Starter:  Complete the following past exam question: Title: Responding to Change Learning Objectives Why do you need a nervous system? What is a receptor? How do you respond to changes in your surroundings? Key Words: stimuli, receptors, impulses, sense organs, CNS, neurons, nerves, secretory organs

The primary goal of the nervous system is to enable you to react to your surroundings and co-ordinate your behaviour. The Nervous System Learning Objectives Why do you need a nervous system? What is a receptor? How do you respond to changes in your surroundings? Key Words: stimuli, receptors, impulses, sense organs, CNS, neurons, nerves, secretory organs

Changes in your surroundings (stimuli) are picked up by cells known as receptors The Nervous System Learning Objectives Why do you need a nervous system? What is a receptor? How do you respond to changes in your surroundings? Key Words: stimuli, receptors, impulses, sense organs, CNS, neurons, nerves, secretory organs

Receptor cells are clustered together in special sense organs, like your eyes or skin. The Nervous System Learning Objectives Why do you need a nervous system? What is a receptor? How do you respond to changes in your surroundings? Key Words: stimuli, receptors, impulses, sense organs, CNS, neurons, nerves, secretory organs

The Nervous System Learning Objectives Why do you need a nervous system? What is a receptor? How do you respond to changes in your surroundings? Key Words: stimuli, receptors, impulses, sense organs, CNS, neurons, nerves, secretory organs

How Your Nervous System Works Learning Objectives Why do you need a nervous system? What is a receptor? How do you respond to changes in your surroundings? Key Words: stimuli, receptors, impulses, sense organs, CNS, neurons, nerves, secretory organs Once a sensory receptor detects a stimulus, the information is sent in the form of an electrical impulse along cells known as neurons.

How Your Nervous System Works Learning Objectives Why do you need a nervous system? What is a receptor? How do you respond to changes in your surroundings? Key Words: stimuli, receptors, impulses, sense organs, CNS, neurons, nerves, secretory organs Neurons are usually arranged in bundles of round a thousand, known as a nerve.

How Your Nervous System Works Learning Objectives Why do you need a nervous system? What is a receptor? How do you respond to changes in your surroundings? Key Words: stimuli, receptors, impulses, sense organs, CNS, neurons, nerves, secretory organs The impulse travels along the nerve until it reaches the central nervous system (CNS)

How Your Nervous System Works Learning Objectives Why do you need a nervous system? What is a receptor? How do you respond to changes in your surroundings? Key Words: stimuli, receptors, impulses, sense organs, CNS, neurons, nerves, secretory organs Sensory Neurons carry nerve impulses from receptors in the body to the CNS. Motor Neurons carry nerve impulses from the CNS to the rest of the body

How Your Nervous System Works Learning Objectives Why do you need a nervous system? What is a receptor? How do you respond to changes in your surroundings? Key Words: stimuli, receptors, impulses, sense organs, CNS, neurons, nerves, secretory organs Impulses that travel along motor neurones cause effector organs like muscles or glands to respond. Muscles contract and glands secrete chemical substances.

2. Complete: Receptor  ___  CNS  ___  Effector 3. Explain what happens in your nervous system when you see a piece of chocolate and eat it. Task Learning Objectives Why do you need a nervous system? What is a receptor? How do you respond to changes in your surroundings? Key Words: stimuli, receptors, impulses, sense organs, CNS, neurons, nerves, secretory organs 1. Your system carries fast impulses. Changes in the are picked up by your