Chapter One : The world Through Our Sense

SENSORY ORGAN

1. Every human have 5 sense .
2. They very important to us .
3. They help us to be sensitive to the changes around us . These changes in the surroundings are kwonw as STIMULI .
4. Light , sound and smell are example of stimuli .
5. We use our SENSORY ORGAN to detect stimuli .

Example of sense .

• Sense of smell
• Sense of taste
• Sense of hearing
• Sense of sight
• Sense of touch

SENSE OF SMELL

1. Our nose not only helps us with our breathing but it is also a sensory organ of smell .
2. The roof of the nasal cavity has many sensory cells or receptors to detect smell .

SENSE OF TASTE

1. The sensory organ for taste os the tongue .
2. Tongue can detect four basic taste : salty , sweet , sour and bitter .
3. All other flavours are made up of these basic taste .
4. Different areas of the tongue are sensitive to different tastes .
5. Our tongue is lined with taste buds which contain many taste receptors .

SENSE OF HEARING

1. Ear is the sensory organ of hearing .
2. It has three main parts : the outter ear , the middle ear , and the inner ear .
3. Most parts of the ear are situated in the skull .

SENSE OF SIGHT

1. Our eyes are responsible for oue sense of sight .
2. Each eye is a slightly flattened ball .
3. The eyelid , a thin layer of skin , protects the front of the eye .
4. The eyeball is held in the eye sockets of the skull by muscles .
5. The wallof the eyeball is made up of three layers : the sclera , the choroid , and the retina .

SENSE OF TOUCH

1. The skin is the sensory organ for touch .
2. It is the largest organ in the body .
3. The skin can detect changes in temperature , pain , touch and pressure .
4. The skin has special receptors to detect each of these stimuli .The sensitivity of the skin depends a lot on how close together the receptors are and how deep they are .