The Senses Part 2! - Ms Di Lallo's Science Class...
Transcript of The Senses Part 2! - Ms Di Lallo's Science Class...
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The Senses Part 2!
Hearing and Seeing are believing!
Smelling
Sight
Touch
Vestibulation / BalanceProprioception / Relative position
Hearing
Taste
The Ears
Organ, key in balance and hearing
Function
1. Allow body to maintain proper balance
2. Sense sound
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The Ear – Cross section (Structures needed in balance)
The Ear- How it “interprets” stimuli of balance• All due to the semi-circular canals
• Canals are filled with liquid and have specialized cilia
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The Ear- How it “interprets” stimuli of balance• All due to the semi-circular canals
• Canals are filled with liquid and have specialized cilia
• When a person moves, the liquid moves in the same orientation, causing the cilia to move
• Cilia transform movement into nerve impulse
• Nerve impulse sent by vestibular nerve to brain
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What is sound?
• Vibrations that travel through a medium (air, liquid or solid)
• They are waves which are produced by an object vibrating• Guitar, piano, vocal cords are all visual examples of how sound is made
Characteristics of waves
Def: Disturbance that travels through a medium transporting energy
Two types (depends on how it travels)
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Characteristics of waves
• Transverse → “bump” in wave is perpendicular to the direction the wave iso Light is this type of wave
Characteristics of waves
• Longitudinal → “bump” in wave goes in the same direction as the wave (parallel)o Sound is this type of wave
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Wave Terminology (Image is transverse wave)
Crest
Trough
Wave Terminology (Image is transverse wave)
Wavelength
Amplitude
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Wave Terminology
Crest: Highest point of wave
Trough: Lowest point of wave
Wavelength: Distance between two crests (one cycle)
Amplitude: Half the height of the wave
Frequency: Number of cycles per unit time
• Higher the frequency, more energy in the wave, higher pitch the sound is
The Ear – Cross section (Structures needed in hearing)
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The Ear- How it “interprets” stimuli of sound
• Sounds waves are collected and funneled by the pinna into the auditory canal
• Sound waves cause the ear drum to vibrate
• The ossicles (hammer, anvil and stirrup) transmit the vibrations from the ear drum to the cochlea
• Cilia in the cochlea translate the vibrations into nerve impulses
• Nerve impulse sent by auditory nerve to brain
Decibel Scale
Def: Scale that represents the intensity of sounds humans can hear
• Each step increases by a factor of 10
Note!! Prolonged exposure to sounds louder than 100 dB can cause long term hearing damage (when I can hear your music in your earphones, that is approx. 100dB, which is high!!!)
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The Eyes
Organ, key in seeing
Function
1. Allow the organism to visualize its surroundings by sensing light
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What is light?
• Vibrations that travel through a medium or a vacuum
• Light, like sound, is a wave (transverse wave)
• Earth’s main source of light is the suno The sun is approx. 150 million km away from the earth
o 1 Astronomical Unit (AU) = 150 million km
Speed of Light
• In a vacuum (no air) light travels at a speed of 300 000 000 m/s
• It takes 8 minutes and 20 seconds (500 seconds) for light from the sun to reach Earth
• The further away you are from the sun, the longer it takes for light from the sun to reach it
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DID YOU KNOW!?!
• The closest star to Earth (besides the sun) is 4.37 light years ( Alpha Centauri)
• That’s 4.13 x 1013 km!o That’s the distance from Montreal, Canada to Sydney, Australia 2.59 x 109
times!!
DID YOU KNOW!?!
• The stars that we see in the sky are “ghosts” from the past
• A lot of the stars we see at night have already “died”; however it has taken thousands of years for that light to travel to Earth
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Electromagnetic Spectrum
• Spectrum of “light” which is visible and invisible to humans
• Humans can only perceive “visible” light,o Light that has wavelengths between 700nm and 390nm
o Longer and shorter wavelengths than visible light humans cannot see
Visible Light
• Longest wavelength: Red; 700 nm
• Shortest wavelength: Violet; 390nm
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White Light Colour Spectrum
DID YOU KNOW!?!
• Bees can see ultraviolet lightoPlants have pigments that are in the ultraviolet spectrum for bees to see
where exactly the nectar is!
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Hanlon, M. (2007, August 8). A bees-eye view: How insects see flowers very differently to us. Retrieved April 14, 2015.
What humans see What bees see
Hanlon, M. (2007, August 8). A bees-eye view: How insects see flowers very differently to us. Retrieved April 14, 2015.
What humans see What bees see
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Hanlon, M. (2007, August 8). A bees-eye view: How insects see flowers very differently to us. Retrieved April 14, 2015.
What humans see What bees see
Behaviour of Light
• Light can only travel in straight lines
• When light meets matter, one of three things can happen1. Reflection: light gets rebounded; “bounces back”
2. Absorption: light gets absorbed by matter
3. Refraction: light goes through matter
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Reflection
• Objects are visible because of reflectiono If objects didn’t reflect light, the light couldn’t get to our eyes, so we couldn’t
“see” the object
Reflection
Incidence Ray Reflected Ray
Angle of Incidence
Angle of Reflection
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Reflection
1. Diffuse reflection: rays reflected in all directions
2. Spectacular reflection: angle of incidence = angle of reflection, get perfect reflection
Two types of reflection:
Reflection- Image made in plane mirror
Object Image
Image is virtualImage has same dimensionsImage is horizontally inverted
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Types of images
Real• Can be captured on a screen
• Light rays cross to make image
Virtual• Cannot be captured on a screen
• Light rays do not cross; image made by extending reflected ray
Absorption
• Absorption allows us to see different colours
• The colour we see is the colour which gets reflected (all other colours are absorbed by the object)
Ex: The sky is blue because it reflects the colour blue, and absorbs all the other colours
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Refraction
• How much light is “bent” as it goes from one transparent medium to another
• Light slows down when it goes in transparent mediums like water, glass, and lenses
Types of lenses
Concave / Diverging
• Spreads light rays outwards
Convex / Converging
• Brings light rays inwards
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Types of lenses
Concave / Diverging
• Only create virtual imagesoReflected rays don’t cross
Convex / Converging
• Create mostly real images(depending where lens is put)
The Eyes
Organ, key in seeing
Key abilities
• Can differentiate approximately 2 000 different colours
• Can adapt to brightness and dimness
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The Eye – Cross Section
Structure Role
Cornea Transparent “cover” over the iris and pupil.
Lens Focuses light rays on retina. Can change its shape to focus images. The lens is behind the pupil.
Pupil* Opening in eye, lets light enter the eye to hit retina
Iris Controls how big/small the pupil gets; “colourful” part of the eye
Sclera “Whites of the eye”; thick white layer, gives shape to eye
Retina Paper-thin layer lining inside of eye. Has photo-receptors which transform light into nerve impulses
Optic Nerve Sensory nerve connected to retina, brings impulse to brain
Vitreous humor Transparent jelly filling inside of eye
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Structure (Extra) Role
Choroid Middle layer of the eye; where blood vessels are found
Aqueous humor Transparent liquid in-between the cornea and the lens
Blind spot Spot on the retina where there are no receptors. No image will be seen here. It is where the retina is connected to the optic nerve
The Eye- How it “interprets” stimuli of light
• Light waves enter the eye through the pupiloMuscles make the pupil big or small depending on the amount of light
• Light waves pass through the lenso Lens flattens or bulges to focus the image you are seeing properly
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The Eye- How it “interprets” stimuli of light
• Focused light hits photoreceptors (sensory receptors) on retina in the back of the eyeo Two types of photoreceptors: Rods (work in low light) and cones (work in
normal light; colour sense here)
• Photoreceptors transform light wave into nerve impulse
• Nerve impulse carried to brain by optic nerve
The Eye – Vision Problems: Myopia (Nearsightedness)
Problem
• Distance images are blurry
• Image forms before the retina
Solution
• Concave/Diverging lenses needed to bring image back towards retina
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The Eye – Vision Problems: Hyperopia(Farsightedness)
Problem Solution
• Close images are blurry
• Image forms after the retina
• Convex/Converging lenses needed to bring image forward towards retina
The Eye – Vision Problems: Astigmatism
Problem Solution
• Lens doesn’t bend properly
• Images are not focused properly
• Specialized lens to focus image properly