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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