CHAPTER 9 THE SENSORY SYSTEM The sensory system
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CHAPTER 9 THE SENSORY SYSTEM • The sensory system makes us aware of our surroundings and allows us to respond. • A stimulus causes us to take an action called a response. © Edco 2007 Exploring Science Biology
CHAPTER 9 THE SENSORY SYSTEM • The sense organs and their senses are: – eyes for sight – ears for hearing – nose for smell – skin for touch – tongue for taste. © Edco 2007 Exploring Science Biology
CHAPTER 9 THE SENSORY SYSTEM • The central nervous system is made up of the brain and spinal cord. • Some nerves carry messages from the sense organs to the brain. • The brain decides how to respond to the stimulus. • Different nerves carry messages from the brain to muscles to cause a response. © Edco 2007 Exploring Science Biology
CHAPTER 9 THE SENSORY SYSTEM Sensory nerves carry messages to the brain. Motor nerves carry messages from the brain. © Edco 2007 Exploring Science Biology
CHAPTER 9 THE SENSORY SYSTEM © Edco 2007 Exploring Science Biology
CHAPTER 9 THE SENSORY SYSTEM The functions of the main parts of the eye are: – The iris controls the amount of light entering the eye. – The pupil lets light into the eye. – The lens focuses light on the retina. – The retina absorbs light to allow us to see. – The optic nerve carries messages from the eye to the brain. – The cornea allows light to enter the front of the eye. (HL) – The ciliary muscle changes the shape of the lens. (HL) © Edco 2007 Exploring Science Biology
