By: Camila F. Gil & Desire Rivera The Senses By: Camila F. Gil & Desire Rivera

Introduction The sensory system is the part of the nervous system that detects or senses the environment. The sensory system includes the five senses: vision, hearing, touch, taste and smell. Thanks to the senses, your brain is able to maintain homeostasis. The receptors; all the parts of the sensory system that detect stimuli. All five senses use different receptors.

Vision Parts of the eye The cornea: A thin membrane that protects the eye and changes the direction of light rays. The iris: Is the colored part of the eye. The pupil: Openning formed by the iris. The lense: Clear opening that light travels through

Vision The retina: Area at the back of the of the eye that has 2 types of cells--rod cells and cone cells--with photorecptors Rod cells: detect shapes and low levels of light Cone cells: detect color and function best in brigt light

Vision

Vision How you see: Light that enters the body has to be detected by the rods and cones in the retina. Rods and cones detect information about colors and shapes of objects from the light that enters the eye The retina then sends informattion as as electric signals through the optic nerve to the brain. Then the brain creates an image by using the information

Vision Focusing Light: The lense and the cornea work together and change the direction of light that entes the eye. Both the lense and the cornea are curved. Those curved shapes change the direction of light and focus onto the cornea.

Vision Why do some people need glasses to see well? If corneas or lenses are not curved exactly right, the eyes will have trouble focusing images. If a person has trouble seeing things that are far away that person might be nearsighted. If a person has trouble seeing things that are up close that person might be farsighted. Glasses or contacts are used t correct vision problems.

Vision

Hearing Hearing: The vibration of matter creates sound waves that travel through air and other substances. The sound waves are detected by the auditory receptors. The sound ampify's as it travels through the ear.

Hearing The Outer Ear: The Middel Ear: The parts of the ear you can see It collects the sound waves that make the eardrum vibrate. Eardrum: Is a thin membrane between the outer and inner ear. The Middel Ear: The vibration pass from the eardrum to small, bones in the middle ear--the hammer,the anvil, and the stirrup. The movement of theese bones amplifies the sound waves.

Hearing

Hearing Inner ear The part of the ear that detects sound is the inner ear. It converts sound waves into messages that are sent to the brain. The structure that looks like a snail shell and is filled with fluid is called cochlea. When the sound waves reach it, the fluid vibrates and moves the hair cells. The moving fluid then bends the hair cells and they send messages to the brain.

Hearing The ear and balance The inner ear has more than one function, besides hearing, it helps you keep your balance. Semicircular canals filled with fluid and hair cells help you maintain balance. When you move your head, you move the fluid inside your ear. The hair cells send messages to the brain. The brain is constantly signaling muscles to move your head and body to maintain your balance.

Smell Humans have hundreds of different receptors for detecting odors. Odors are molecules that are detected by chemical receptors called chemoreceptors. Chemoreceptors detect chemicals in the air and send messages to the brain. Once the brain is done processing this messages, we perceive what we call smell. A smell is so powerful it can make you hungry or trigger a memory or feeling.

Taste This sense also relies on chemoreceptors. This chemoreceptors detect chemicals in drinks or foods, not in the air. Chemoreceptors on your tongue are known as taste buds. Taste buds detect 5 tastes: bitter, salty, sour, sweet and umami. Umami is the taste of MSG (monosodiumglutamate), often used in processed foods. Chemoreceptors in your nose and mouth work together to help you taste and smell foods.

Smell and Taste

Touch Touch receptors in your skin can detect temperature, pain and pressure. They can detect the difference between a light tap and a poke. They are all over your body, but the palms of your hands and the soles of your feet have a higher concentration of receptors. Also the middle of your back has a fewer concentration of receptors.

Homeostasis and Stimuli Homeostasis is when you respond to stimuli, or the things around you, like finding food and water and avoiding harmful environments. Gathering information about your environment is crucial for your survival. Your brain is able to respond and activate your body to maintain homeostasis. Your senses are the vital first step to sensing important homeostasis like finding food and water and avoiding harmful environments.

Homeostasis Song By Mr. Parr http://www.youtube.com/watch?v=1iPndNB7mjw