What’s in the bag? Blind fold students or (take away other senses) and have them identify different objects. Explain that senses help us receive information about our surroundings (and more than one sense can be used) What’s in the bag? Blind fold students or (take away other senses) and have them identify different objects. Explain that senses help us receive information about our surroundings (and more than one sense can be used) Also discuss the difficulty that comes with loosing a sense Also discuss the difficulty that comes with loosing a sense See which student can identify the most objects See which student can identify the most objects

The Senses Ch. 36.2

I. Use Your Senses A. Your body has 5 senses: 1. Sight 2. Hearing 3. Touch 4. Taste 5.Smell

I. Use Your Senses B. Senses are often linked together in the brain 1. Chemicals from an orange stimulate sensory neurons in your nose and you smell the citrus smell

I. Use Your Senses 2. Chemicals from the orange stimulate the sensory neurons of the tongue when you eat it so you taste the flavor. 3. Food doesn’t have much flavor with a stuffy nose because you can’t smell it

II. Taste A. Taste Buds- The sensory receptors on your tongue 1. Young adults have appx. 10,000 taste buds 2. The # of taste buds decreases over time and smells and tastes are dulled

II. Taste B. Taste buds categories 1. Salty 2. Sour 3. Bitter 4. Sweet 5. The “Pill Spot?”

III. Sight A. Sight depends on light energy reaching sensory receptors in the eye. 1. Light passes through the cornea first a. The outside window of the eye

III. Sight b. Astigmatism is caused by an uneven cornea 1) Special lenses are needed to correct it

III. Sight 2. Light passes through the iris and into the pupil a. The iris regulates the size of the pupil and how much light enters b. The iris also gives they eyes color

III. Sight 3. The light image is then focused by the lens on to the retina. a. The image is smaller & up-side-down & backwards

III. Sight b. When objects viewed are distance the lens is flat c. When objects viewed are near the lens becomes more rounded d. The lens is associated with glaucoma (too much fluid)

III. Sight e. If the eyeball is naturally too long or short, corrective lens (glasses) may be needed 1) Near sighted (long eyeball) = Concave Lens 2) Farsighted (short eyeball) = Convex Lens

III. Sight 4. The retina contains the cones and rods a. Cones are receptor cells adapted for sharp vision in bright light b. Cones also detect color

III. Sight c. Rods are receptor cells adapted to detect shape and movement in dim light d. There is a place with no rods or cones called the blind spot 1) Paper demo

III. Sight e. Sensory neurons in the retina form the optic nerve that carries the image to the brain f. The brain interprets the message, flips and rotates it and responds (or not)

IV. SOUND A. 3 parts of the Ear 1. Outer Ear 2. Middle Ear 3. Inner Ear B. Sound is caused by vibrations in the air around it (sound waves)

IV. SOUND C. Outer Ear 1. Sound waves are captured by the cup shape of the ear (Pinnea) 2. They travel through the ear canal

IV. SOUND C. Outer Ear (cont) 3. The sound waves strike the ear drum (tympanic membrane) and cause it to vibrate

IV. SOUND D. Middle Ear 1. The vibrations then pass to 3 small bones of the middle ear: a. Malleus b. Incus c. Stapes

IV. SOUND D. Middle Ear (cont) 2. As the stapes vibrates, it causes the oval window to move back and forth a. Oval window is the membrane between the middle and inner ear

IV. SOUND E. Inner Ear 1. The movement of the oval window causes the fluid inside the cochlea to move. a. Cochlea is snail shaped structure

IV. SOUND 2. The movement of fluid causes the hair cells lining the cochlea to move a. Damage to hair cells causes hearing loss

IV. SOUND 3. Electrical impulses are sent along the auditory nerve to the brain. a. Sound is interpreted by the cerebrum b. Auditory nerve damage also causes hearing loss

IV. SOUND P innea E ar canal T ympanic membrane M alleus I ncus S tapes O Val window C ochlea A uditory nerve

V. BALANCE A. Spin Demo B. The inner ear also sends messages to the brain about the position of the head. C. Semicircular Canals-

V. BALANCE C. Semicircular Canals 1. Fluid filled 2. Lined with hair cells 3. Tilting the head causes the fluid to move and the hair cells to bend.

V. BALANCE C. Semicircular Canals (cont) 4. Nerve impulses are sent to the brain to be interpreted a. Cerebellum? 5. Motor neurons cause the neck muscles to adjust the position of the head.

VI. TOUCH A. Sensory neuron receptors are found in the skin 1. Temperature Neurons a. Cold- Found near the skin surface b. Heat-Found deeper in the dermis

VI. TOUCH c. Indicates that cold is more of a threat than heat

VI. TOUCH 2. Light Pressure Neurons 1. Found in fingertips, eyelids, lips and the tip of the tongue 2. More sensitive areas of the body

VI. TOUCH 3. Heavy Pressure Neurons 1. Found in joints, muscle tissue and certain organs 2. Also found in hands, and feet

VI. TOUCH 4. Pain Receptors 1. Found in all body tissues except brain tissue