Eyes Ears &

The human eye Photons are packages of light energy that enter our eye through the pupil at the front.

The human eye Cornea Pupil Iris Lens Ligaments Ciliary body Aqueous humor Vitreous humor Sclera Choroid Retina Fovea Optic nerve

The human eye Humans have binocular vision. The visual fields overlap giving each eye a slightly different view. Muscles in the eye coordinate so that the eyes move in the same direction at the same time, if they did not we would have double vision.

The human eye With myopia, the focal point does not reach the retina, so a diverging lens is needed in front of the eye to focus the light on the fovea. Focal point is in front of the fovea The law of refraction allows light to be refocused through the glass lens onto the fovea

The human eye With hyperopia, the focal point reaches beyond the retina, so a converging lens is needed in front of the eye to focus the light on the fovea. Focal point beyond the fovea The law of refraction changes the focal length to allow light to be refocused through the glass lens onto the fovea

The human eye Rod cell Cone cell But how does our eye actually allow us to see?

The human eye Rods and cones contain sensitive receptors that recognise the colours Blue Red Green Cones on the other hand do not see colour, they are good at detecting shades of black and white and are useful for night vision.

The human eye Rod Cone Optic nerve The rods and cone cells are lined up along the retina

The human ear Hearing in the passive function of sound reception whereas listening is the ability to focus on the sounds we want, and to ignore those we do not want. The human ear is part of the human sensory system and allows us to hear wave vibrations, otherwise known as sound. Let’s have a look at the human ear and learn how it functions...

The human ear Outer ear Middle ear Inner ear Pinna Auditory canal Tympanic membrane Malleus Incus Stapes Semicircular canals Round window Coclea (with section removed to show inside) Nerve Eustachian canal

The human ear The outer ear collects sound waves and transports them to the tympanic membrane The middle ear has 3 functions, (1) it transmits the sound waves to the inner ear (2) reduces the amplitude of vibrations to help protect the ear from damage and (3) equalizes the pressure on both sides of the tympanum to prevent it rupturing - it does this by letting in air via the eustachian canal The inner ear converts the wave energy to electrical impulses that are sent along nerve fibers to the brain and also help maintain our balance. The 3 parts of the ear all have different jobs to do...

The human ear Cochlea Nerves Pitch Low frequency High frequency One wave length

The human ear The smallest bone in the human body is... The Stapes. It is only 0.25 to 0.33 cm long. Time for a random Science Fact:

The human ear Loudness is measured in decibels (dB) - this is the force of sound waves against the ear. The louder the sound, the more decibels recorded. Sound Intensity (db) Ticking of a Watch 20 Whisper 30 Normal Speech Car Traffic 70 Alarm Clock 80 Lawn Mower 95 Chain Saw 110 Jackhammer 120

The human ear Things that can go wrong with the ear: The tympanum (ear drum) can become perforated The ear can become infected (usually the ear wax helps prevent this) The hairs that convert sound waves to electrical impulses can be damaged. Generally the damage is irreparable. They degenerate with age, this reduces the quality of sound.

The human ear Of course you would have noticed that if you spin around in circles you will get dizzy. But do you know why? When you spin, fluid in the semicircular canals of your ear moves around. This stimulates the hair cells. When you stop spinning, the fluid still moves a bit. Because the fluid is still activating hair cells, your brain stills gets a message that you are moving and you feel dizzy.

The human ear Human ears are grown on the back of nude mice the ears are grown from cartilage implants once they are grown to the right size the ears are removed and transplanted into humans researches say there is minimal impact on the lives of the mice what do you think/feel about this kind of technology?

The End!