
Describe the anatomy and function of the human eye including the :
- Conjunctiva
- Cornea
- Sclera
- Choroid
- Retina
- Iris
- Lens
- Aqueous and Vitreous Humour
- Cilliary Body
- Optic Nerve
Structure
Conjunctiva
Cornea
Function
A Layer of epithelial cells that help to keep the eye moist
Protects and supports the front structure of the eye to
prevent foreign objects entering the Eye. It also acts as a
refractive medium for the eye
Sclera
The sclera is the outer surface of the Eye that helps to
support and protect the Eye. It also gives the Eye its white
appearance.
Choroid
The Choroid is situated between the Sclera and Retina, its
serves as an additional form of protection and extends to
the Iris.
Retina
The Retina is the inner most layer of the protective surface
of the Eye. It also contains the Photoreceptor Pigmentation,
Nerves and Blood Vessels for the Eye.
Iris
The Iris is the colour part of the front of the Eye containing
many fibrous muscles. Its also regulates the amount of light
that enters the eye
Lens
The lens is a transparent biconvex protein disc located
behind the pupil. It is responsible for the reflection of light
towards the Retina.
Aqueous and Vitreous Aqueous Humour and Vitreous Humour sub - fills the front
Humour
chamber of the eye. Vitreous Humour is a jelly like
substance that keeps the eyeballs shape as well as acting as
a refractive media for the refraction of light towards the
Retina
Cilliary Body
The cilliary Body connects the Choroid with the Lens. It
contains a suspensory ligament as wells as Cilliary Muscles.
It is used to hold the Lens in place as well as altering the
shape of the Lens for the purpose of accommodation.
Optic Nerve
The Optic Nerve connects the Eye ball to the Brain. It is also
known as the blind spot as no image cab be made or
processed due to the lack of photoreceptors. It carries
nerve impulses that are produced by the Eye to the Visual
Cortex of the Brain so that images can be translated and
Produced.
http://media2.web.britannica.com/ebmedia/57/72157-035-3A4E50BE.jpg

Identify the Limited range of waves lengths of the electromagnetic spectrum
detected by humans and compare this range to those of other vertebrates and
invertebrates
http://www.williams.edu/astronomy/Course-Pages/111/Images/ems.jpg
Organism
Human
Vertebrate: Bat, Dolphin, Whales
In-Vertebrate: Bee
Wave Length (nM)
Visible Light: 400 - 700
Use of Sonar Type Waves: 0
Visible light: 10-400

Use available evidence to suggest reason for the differences in range of
electromagnetic radiation detected by humans and other animals.
Within the wider environment there are many different niches that different
organism inhabit. These niches produced different challenges and obstacles for an
organism to overcome in order to survive and procreate. Each organism needs to be
able to detect predators and pray that may be contained within their habitat in order to
survive. This detection may come in the form of the different electromagnetic spectrum
fields.
For example electric Eels smit an electromagnetic field within their environment,
water, any disturbance to this field such as that of pray or a predator within the
environment is detected by the Eel. Subsequently the pray is consumed or the predator
can be avoided. Eels use this form of electromagnetic radiation within their aquatic
environment as in most instances visibility is quiet poor.
Other examples of organisms that use these
different forms of electromagnetic fields to live
within their particular environment include; the
Platypus which uses electromagnetic receptors
contained within its bill, Snakes who use Infra Red
Light, Bees who use UV light to detect nectar within
flowers and even humans us two single lens eyes to
detect visible light within and environment.

Identify the conditions under which the refraction of light occurs.
Light Refraction occurs when light Waves travel through a medium from a higher
light density to a lower light density or visa versa. The refraction of light from air to
water is one example of the Refractive nature of light.
This image presented the
refractive nature of light when
passed through two separate
mediums. Light enters and
enters the mediums at the
same angle but the angle and
position that they leave the
media is adversely different.
http://micro.magnet.fsu.edu/optics/lightandcolor/images/refractionfigure1.jpg
This diagram presented the
nature of white light as it
passes through a prism and
colour is produced. It is said
that when light bends it does
so away from the norm as
presented
within
this
diagram.
http://media-2.web.britannica.com/eb-media/03/5703-004-594D0C62.gif

Identify the cornea, aqueous humour, lens and vitreous humour as refractive
media.
Refraction occurs within the eye Ball when light waves are bent towards the
Retina to focus light on a particular point to develop and image. This refraction occurs
through the use of refractive media. These forms of media include the Cornea, the
Aqueous Humour, the Vitreous Humour, and the Lens. The process involves light
entering the eye through the Cornea and is bent through towards the Aqueous Humour,
progressing through the Lens and onto the Vitreous Humour and finals focused upon
the retina.
http://www.nei.nih.gov/healthyeyes/eye_imag
es/Normal.gif

Identify accommodation as the focusing on objects at different distances,
describe its achievements through the change in curvature of the lens and
explain its importance.
Accommodation is the ability of the lens to change or adjust to the shape in
order to focus light from objects at a range of distances. If the lens becomes more
rounded, or convex it reflects light to a
greater extent and closer objects cans be
focused. If the lens becomes less rounded
it reflects light less and distant objects can
be focused.
http://www.sapdesignguild.org/editions/highlight
_articles_01/images/accomodation.png
Light rays reflected from another object six meters or more away are almost
parallel to each other. The lens refracts these light rays so that they focus upon the
fovea, the part of the retina which a visual image is produced and is the sharpest. If and
object is closer than six meters the light rays that reflect off the object will be diverging
rather than remaining parallel. To bend these light rays so that they fall on the fovea
producing the sharpest possible image, the lens must become less rounded to
accommodate for the distance of the object.
The cilliary muscles are responsible for the adjustment of the shape of the lens.
When they are relaxed the lens becomes less rounded. When they are contracted the
lens becomes more rounded.
Accommodation is important because it allows the eye to form focused images
upon the retina from objects at a variety of distances from the eye. As a person ages
they gradually begin to lose the elasticity within their eye and it can no longer properly
accommodate to view closer objects. Corrective
lenses (Glasses or Contact Lenses) are usually
required.
http://www.daviddarling.info/images/corrective_lenses.jpg

Compare the change in the refractive power of the lens from rest to maximum
accommodation
Rest
Vision: Far
Tension: Muscle’s relaxed
Refractive Power: Low
Lens: Thin / Elongated
Maximum Accommodation
Vision: Near
Tension: Muscles Contracted
Refractive Power: High
Lens: Bulging / Increased Curvature
The refractive Power of the eye is lower when focusing on a distant object
because the light is travelling through the lens at less of an angle and therefore requires
less effort to focus. Opposing this with a closer object where the angle of light is greater
which will require an increased curvature of the lens, inturn increasing the refractive
power of the lens.
http://clearvieweye.net/blog/wp-content/uploads/2010/01/accom.gif

Distinguish between Myopia and Hyperopia and outline how technologies can
be used to correct these conditions
Myopia: Short Sightedness
Hyperopia: Long Sightedness
http://www.roseopticals.com/images/youreye/Myopia_lg.jpg
http://www.austincountyeye.com/graphics/Hyperopia_austin_county.jpg
Myopia is essentially short sightedness within and individual. A person with
Myopia sees objects that are at a distance less than 6 meters or so with greater clarity
but has trouble focusing or distinguishing objects at distances greater than six meters.
Rays of light from distant objects are focused in front of the retina. The usual cause of
Myopia is that the eye ball is elongated.
Hyperopia is essentially long sightedness. A person with Hyperopia sees objects
that are in the distance with great clarity, but close objects are seen as out of focus.
Rays of light from close objects are focused behind the retina rather than right on it. The
usual cause of Hyperopia is that the eye ball is to short and therefore the lens causes
parallel rays of light to converge slightly so that they focus behind the retina.
You Tube Video Link:
http://www.youtube.com/watch?v=ekSGbXt4XdI
Technologies used to correct these conditions include; Glasses, Contact Lenses,
or Surgery. Myopia can be corrected through concave lenses worn for distance vision.
These lenses cause the parallel rays of light to diverge slightly before entering the eye so
that the focus of the light is upon the retina.
Hyperopia can be corrected with convex lenses worn for viewing near objects.
These lenses cause the parallels rays of light to converge slightly before entering the eye
so that they focus upon the retina.
You Tube Video Link:
http://www.youtube.com/watch?v=dZZguJNitnU
Refractive surgery may also be used to treat both Myopia and Hyperopia. A thin
flap of skin is cut and folded back. A laser is used to reshape the cornea to a more
suitable shape. The fold of skin is then put back into place.

Process and Analyse information from secondary sources to describe cataracts
and the technology that can be used to prevent blindness from cataracts and
discuss the implications of this technology on society.
A cataract is characterised by the
clouderning or thickening of the lens within
the eye. It is believed that the cause of
cataracts is insufficient nutrients in the lens
fibres due to the increased density of the
fibres. The crystalline protein fibres in the
lens are then oxidised. They clump together
forming the cloudiness or thickening within
the eye.
http://visione360eye.com/images/cataract_20example520.jpg
There are different types of cataracts for example age related cataracts,
radiation – induced cataracts and infectious cataracts. Age related cataracts develop
because free radicals and other oxidising chemicals can penetrate the lens as the eye
ages. This causes the oxidation of the crystalline protein.
Radiation – induced cataracts can occur in young people and currently occurs
within developing countries. All cataracts involve the clumping of crystalline protein
within the eye. IN the case of radiation – 0-induced cataracts the clumping is caused by
excessive exposure to UV light or insufficient antioxidants within an individuals diet.
Infectious cataracts are due to the invasion of pathogens into the eye. For example
rubella virus can cause cataracts within the
foetus if the disease is contracted by a pregnant
female.
The technology for preventing the
development of cataracts is the use of sunglasses
and an adequate diet. However in cases were the
cataract has already developed and there is a
high risk of blindness surgery is the answer. This
form of micro surgery is known as
Phakoemulsification.
http://jirehdesign.com/images/illustrations/SUCA0025.jpg
Phakoemulsification is a technique that takes very little time, it is performed
under local anaesthetic and can be performed anywhere, making it extremely helpful in
Third World Countries. It has revolutionised the treatment of cataracts so that a wide
array of unnecessary blindness no longer occurs.
You Tube Video Link:
http://www.youtube.com/watch?v=htx-vFceJZI&feature=related

Identify Photoreceptor cells as those containing light- sensitive pigments and
explain that these cells convert light images into electromagnetic signals that
the brain can interpret
Photoreceptors contain light sensitive pigments known as rods and cones. These
cells convert light into electrochemical signals that the brain is able to interpret as an
image. These electrochemical signals contain a wave of sodium and potassium ions
which move across the cell membrane of the neurone.

Describe the differences in the distribution, structure and function of
photoreceptor cells within the human eye
The retina consists of a thin layer of photoreceptor cells. These are light sensitive
cells that are activated by light energy to produce and impulse which travels along the
neurones that link them to the brain. In the retina there are two types of
photoreceptors; Rods and Cones. Both of these cells are modified neurones. They are
not distributed around the retina equally.
Rods are long shaped cells, which are sensitive to low levels of light but are
unable to distinguish between colours. The image formed by the brain, using the
information from the rod cells lacks detail. Rods are linked in groups to single neurones.
Rods are found mainly around the periphery of the retina and there are none contained
on the fovea. They are more suitable for night vision, When the pupil is dilated more
rods are exposed allowing a greater amount of light to be absorbed. Rods also detect
movement very well.
This diagram shows the receptor path way
that light travels through when it enters
and is transferred into electrochemical
messages that can be interpreted by the
brain as and image
http://www.colourtherapyhealing.com/colour/i
mages/rods_cones.gif
Cones are conical cells which
contain a pigment which is only
sensitive to high intensities of light but
exist in three different forms so that these cells can distinguish between different
colours. They have extensive nerve connections with the brain and produce a more
detailed image. The number of cones increases towards the centre of the back of the
retina. At the centre of the retina a small area known as the fovea, which has densely
packed cones only is present. The fovea corresponds to the region of maximum visual
clarity.
http://www.eyedesignbook.com/ch3/fig3-61retinarodsconesBIG.jpg
Cones are more suitable for day vision. In
bright light, when the pupil is contracted, it will be
mainly cones that are active. AS cones require light
of a high intensity to stimulate them, it follows that
it is harder to distinguish colour in poor light. Visual
activity is dependant on the number of cone cells present per unit area. The more there
are the greater the number of impulses that are passed onto the brain for an image to
be produced.

Outline the role of Rhodopsin in Rods
Rhodopsin is a light
sensitive
pigment
which
consists of two molecules
bonded together, opsin and
retinal. When light enters a rod
cell, it splits the Rhodopsin
molecules into its two
components. This reaction
results in an impulse in the
neurone attached to the Rod.
The two products slowly
recombine waiting to be split
by more light. This process is
known as the Visual Cycle.
Rhodopsin is the pigment that is most sensitive to lower wavelengths of light
that is Blue or Green light. This process is also more active when in duller light or even
darkness.
This image
displays a
detailed
microscopic
view of Rod and
Cone cells.

Identify that there are three types of cone, each containing a separate pigment
sensitive to either blue red or green light.
There are three separate types of cones. Each
contains different photo pigments. The Trichromatic
theory of colour vision suggests that each is sensitive to
a different range of light wave lengths, corresponding to
three types of visible colours; red, green and blue. The
sensitivity of these photo pigments is board enough to
allow them to cover the full spectrum of visible light.
Each pigment is thought to be located in different cones
and different colours are perceived in the brain from
sensory input from combinations of these three cones.
Thus the brain builds up a colour image according to the
number of impulses received from the three separate
cones within the eye.
Light energy --------> electrochemical energy
Ganglion ----> Bipolar ----> Rods (Rhodopsin) ----> Bipolar
----> Ganglion ----> Optic nerve
Rods: Detects shades of light
Contains Rhodopsin
Cones: Detects various colours ----> Sharp Images
Contains Photopsin



http://www.rpdms.com/satillusion/co
nes.jpg
Large concentration of Rods in entire eye
Cones more concentrated on fovea
Rods can also detect movement
This diagram displays the distribution of
Cone receptor cells and Rod receptor cells
within the Human Eye
http://starizona.com/acb/ccd/advimages/eye01.gif\

Explain how the production of two different images of a view can result in
depth perception
Depth perception is simply the ability of the eye to measure the distances
between the eyes and an object. When the eyes face forward each eye sees and image
of an object in the light path. The two images are fused into one image in the cerebral
cortex of the brain. This fusion into one image is the relation to the perception of depth.
Depth perception is the sense of depth that
occurs when objects are viewed with binocular
vision.
Stereoscopic Vision: Three dimensions
Focused on different places
on the retina

Explain that colour blindness in humans results from the lack of one or more of
the colour sensitive pigments in the cones
Colour blindness occurs when individuals are unable to distinguish between
certain colours. Because colour blindness is predominantly caused by a sex linked
genetic defect it is more common in males than females.
The most common form of colour blindness is Red-Green Colour blindness; it is
also scientifically referred to as Protanopia/Deueranopia. It results from a lack of either
red or green cones within the eye. The other more rare form of colour blindness is that
of blue yellow colour blindness. In this form there is a decreased of absence of blue
cones within the eye and is known as Tritanopia.
Red-Green Colour Blindness Spectrum:
Spectrum:
Blue
http://w
ww.colb
lindor.co
m/wpcontent/
Yellow
Colour
Blindness
images/Protanopia-Color-Spectrum.jpg
http://www.colblindor.com/wp-content/images/tritanopia-color-spectrum.jpg
The obvious most extreme form of colour blindness is total colour blindness. This
is where there is a genetic malfunction within and individual and they see no colour at
all due to the nature or absence of Cone Photoreceptors within the eye.
http://micro.magnet.fsu.ed
u/primer/lightandcolor/ima
ges/humanvisionfigure7.jpg
This image is a typical test
used to determine weather
of not an individual has a
specific form of colour
blindness.

Single
Lens Eye
Process and analyse information from secondary sources to compare and
describe the nature and functioning of Photoreceptor cells in a mammal, an
insect and one other animal
Organism
Human and Lion
(Mammal)
Pray Mantis
Compound
(Insects)
Eye
Photoreceptors
Rods and Cones
Ommatea
Single Lens Eye
Function
The retina contains rods and cones which contain
visual pigments that absorb light. This initiates
changes in the transmission of neurotransmitters
that pass messages via the optic nerve to the brain.
Hence light is converted into electrochemical
impulses interpreted as visual images by the brain
An insect’s eye contains thousands of light detecting
units called Ommatea. Each Ommatea has its own
lens, which focuses light into light absorbing
pigments. These pigments are arranged in a stack of
plates situated inside a layer of receptor cells. The
altered pigments initiate a nerve impulse. Which is
transmitted to nerve fibres relaying the image to the
brain and producing vision
Compound
Lens Eye

Process and analyse information from secondary sources to describe and
analyse the use of colour vision for communication in animals and relate this to
the occurrence of colour vision in animals
Colour vision is dependant on the presence of cone photoreceptor cells within the
eye. Bees and some other pollinating insects can actually see the ultraviolet light
spectrum and can visually see the patterns on flower petals that are not coloured
specifically. Vertebrates have good colour vision although not all species can see colour.
Most fish, amphibians, reptiles and birds can see in colour, but most mammals can not.
Nocturnal animals uses rods to a more predominant
effect rather than cones and therefore do not see in colour.
For Primates that mainly feed on fruit, colour vision enables
them to detect the colours of fruit and determine if the fruit is
ripe and ready to eat. Birds are strongly attracted to the
colour red and frequently visit flowers that are redish in
colour. Their photoreceptor pigments are adapted to absorb
wavelengths of light in the red region, thus they detect red
http://thumbs.dreamstime.com/thumb_381/123
objects within their environment quiet easily.
8427887gL8855.jpg
Colour Vision is a most effective way of detecting and responding to the
surrounding environment and in turn developing a distinct form of communication and
interaction between organism and niche.

Explain why sound is a versatile form of communication
Various organisms use sound as a device of communication with one another.
Sound is a versatile form of communication as organisms can vary the sounds that they
produce to signal for various dangers or even communicational purposes. Sound is
effective in day and night and is able to travel through solids unlike light. Sound is also
directional and can travel for long distances making it a highly effective form of
communication.
http://robpaterson.files.w
ordpress.com/2009/03/so
und_wave.jpg

Explain that sound is produced by vibrating objects and that the frequency of
the sound is the same as the frequency of the vibration of the source of the
sound
Sound is a form of energy that requires a material medium, a solid, a liquid or a
gas, for its transmission. Sound is produced when an object vibrates at a certain
frequency, these vibrations are transferred through a medium and a receiver detects
the vibrations and converts them into sound.
Speech is a sophisticated form of sound produced by the vibrations of vocal
cords in the larynx. The tension and length of the vocal cords and the opening of the
glottis in the larynx alter the pitch and production of sound. The force of the air passing
through the vocal cords alters the loudness or volume of the sound produced.
Larynx  Air  Ear  Structures vibrate at 100 Hz interpreting sound
(100Hz) (100Hz) (100Hz)
http://www.teenbuzz.org/decibels.png

Outline the structure of the human larynx and the associated structures that
assist the production of sound
The Larynx or voice Box is situated below the tongue and soft palate within the
mouth. Within the Larynx there are vocal cords which consist of muscles that adjust
pitch and volume through the alteration of their position and tension. There are nine
different cartilages that also make up this section of the
structure. The vocal cords attach to the cartilage and
stretch across the tracheal opening. The elastic fibre
structure and tracheal open makes up the Glottis.
Together these structures, the Tongue, Soft palate, Larynx
and Glottis make speech possible. Depending upon the
tension developed within the vocal cords the pitch or
volume of the sound produced will differ.
Tense Vocal Cords = Faster Vibrations = High Pitched
Sound
Relaxed Vocal Cords = Slower Vibrations = Lower Pitch
soun
http://www.biologycorner.com/anatomy/respira
tory/Larynx%20front.jpg

Outline and Compare the detection of Vibrations by Insects, Fish and
Mammals.
Medium
Transmitting Sound
Structure Sensing
Sound
Insect
Air, Solid – Ground
Leaves
Tympanic
Membrane, Hair
Cells
Sensory Cell
Mechanoreceptors
Fish
Liquid - Water
Mammal
Air or Liquid
Swim Bladders and
internal ears,
Lateral line System
of Neuromasts
Hair Cells in
Neuromasts
Cochlea
Hair Cells in Organ
of Corti
Each and ever animal has some form of receptor that is used to detect vibrations
in order to identify sound. Through this reason they are able to “hear” incoming sound
and gather information such as distance and direction of other dangers or potential
food sources within their environment.
Mammals have three main sections within their ears that allow them to detect
sound. Those sections are the External Ear that is used to collect the vibrations, The
Middle ear which is used to transmit the vibrations and the Inner ear, containing the
Cochlea, which is used to interpret the vibrations as sound forms.
It is stated that sound travels faster within water, as water acts as a medium for
the vibrations transmitted. It is for this reason that Fish’s ears are located within their
body. With different species of fish come different methods of detecting sound. Some
fish utilise Swim Bladders in order to detect sound. Fish also use Neuromasts to detect
movement within the water. Neuromasts have Hair Cells very similar to that of the
Organ of Corti contained within the Mammalian Ear. The second form of sound
detection for fish is a Lateral line System. This system contains a series of small canals
situated around the head and sides of the fish that contains Neuromasts.
Similarly to the Fish with the different species, different types of Insects of
insects have different structures of sound receptors that interpret sound. Moths for
example have a tympanic membrane structure that is located upon their chest or
abdomen. Mosquitoes have Hairs upon their antennae that detect the vibrations
produced from sound within the air. Ants use mechanoreceptors that are located upon
their legs that detect sound vibrations that travel thorough the ground.
http://misclab.umeoce.maine.edu/boss/clas
ses/SMS_491_2003/sound/Dusen9_17.jpg

Describe the anatomy and function of the Human Ear, including
- Pinna
- Tympanic Membrane
- Ear Ossicles
- Oral Window
- Round Window
- Cochlea
- Organ of Corti
- Auditory Nerve
Name
External (Outer) Ear
Pinna
Structure
Ear Canal
The Ear Canal is the tube leading
from the Pina to the tympanic
Membrane.
Tympanic Membrane
(Ear Drum)
The Tympanic membrane is
situated between the External Ear
and the Middle Ear.
Middle Ear
Ear Ossicles
Oral Window
Round Window
Comprises of various fold of Skin
enveloping cartilage.
The Ear Ossicle consists of three
main bones within the middle ear
known as the Malleus (Hammer),
the Incus (Anvil) and the Stapes
(Stirrup).
The Oral window is a small, thin
membrane structure situated
between the Middle and Inner Ear.
The Round Window is situated just
bellow the Oral Window.
Function
- The Pinna collects sound and
channels it down the ear
canal towards the ear drum.
- It helps to determine to
direction of various sounds.
- It also protects the internal
parts of the ear.
- The ear canal Channels the
sound wave towards the
Tympanic Membrane.
- It also produces a waxy
substance that protects and
lubricates the Ear.
- The Tympanic Membrane
vibrates with the same
frequency as the sound wave
that hits it.
- It also provides as an airtight
protection between the
external and Middle Ear
- These specific bones transfer
the vibrations from the
tympanic Membrane across
the Middle Ear to the oral
Window.
- It also acts as a leaver to
reduce amplitude.
- The Oral Window reduces the
vibrations from the Tympanic
Membrane via Ossicles.
- The Round window acts like a
piston to transfer the
Vibrations from the Oral
Window to the fluid
contained within the Inner
Ear.
Inner Ear
Cochlea (Snail Shell)
The Cochlea is a long tube wound
around itself in the shape of a snail
that is filled with liquid.
Organ of Corti
The Organ Corti is situated inside
the Cochlea. It Contains millions of
receptor Hair cells that are
attached to nerves that assist in
the interpretation of sound.
Auditory Nerve
The Auditory nerve is a bundle of
nerve fibres bound together.
Eustachian tube
The Eustachian Tube is a narrow
tube that opens within the Middle
ear and leads to the Pharynx.
- The Fluid within the Cochlea
transfers the vibrations
contained within the ear from
sound to the Hairs within the
Organ of Corti.
- Within the Organ of Corti Hair
cells are tuned to certain
wave frequencies. When the
Waves pass over the Hair cells
electrical signals are triggered
and sent to the Auditory
Nerve.
- The Auditory Nerves send the
electrical signals that are
produced by the organ of
Corti to the brain to be
interpreted as sound.
- The Eustachian tube is used
to equalise the pressure
between the External and
Middle ear.
http://www.nlm.nih.gov/medlineplus/magazine/issues/fall08/images/humanear_anato
my.jpg
 Outline the role of the Eustachian Tube
The main function of the Eustachian Tube is to equalise the pressure between
the Outer and Inner Ear. This is done so that the Tympanic membrane is not forced into
a position within the ear that causes it to not work to its full capacity. The Eustachian
Tube is able to equalise the pressure that builds up within the ear as it is connected to
the Inner Ear and the Pharynx that is occupied by the outside air, allowing for a release
in strain that my be placed upon the tympanic Membrane.
Notable situations where the Eustachian Tube equalises the pressure within the
ear may include when an individual is in an Aeroplane as it takes of or when someone is
Deep Sea dividing. The pressure from the surrounding environment as the Air begins to
thin causes strain to be placed upon the Tympanic Membrane causing the “Popping”
sensation.
http://drharris.ucsd.edu/Portals/0/Eustachian%20tube
%20cropped%20(NLM).jpg

Outline the path of a sound wave through the External, Middle and Inner Ear
and identify the energy transformations that occur
Sections
External Ear.
Structure
Pinna.
Auditory Canal.
Tympanic Membrane.
Middle Ear.
Ear Ossicles.
Oral Window.
Inner Ear.
Cochlea.
Organ of Corti/Hair Cells.
Auditory Nerve.
Energy Form
Sound Energy.
Physical Occurrences
Sounds is Emitted
Vibrations enter Outer
Ear.
Mechanical Energy.
Causes the Tympanic
Membrane to vibrate at
the same frequency.
Causes the Ossicles in
the Middle ear to
Vibrate.
Softens the impact of
the Vibrations
Causes the Fluid in the
Ear to vibrate
Electrochemical
Produces tension on the
Energy.
hair cells in the Organ of
Corti
Activates neurons that
transfer nerve impulses
to the brain
Interpreted as sound
Brain.

Describe the relationship between the distribution of hair cells in the Organ of
Corti and the detection of sound of different frequencies.
Within the Inner Ear there is a structure contained
within the Cochlea representing a ribbon shape known as the
Organ of Corti. The organ of Corti is responsible for the
interpretation of the frequency of sound waves that are
converted into electrical signals that are sent to the Brain. There
are three main components contained within the Organ of Corti
that assist in the interpretation of these sound frequencies that
include; the Tectoral Membrane, Hair Cells and the Basilar
Membrane.
http://www.hhmi.org/images/bulletin/sept2005/inner-ear.jpg
The Basilar Membrane is comprised of transverse fibres of different lengths.
Vibrations from the Middle Ear are transmitted through the cochlear fluids which inturn
cause the transverse fibres of the Basilar Membrane to vibrate in specific places in
accordance with the frequency presented by the sound wave.
http://www.colorado.edu/intphys/Class/IPHY3730/image/figure8-14.jpg
As the Basilar membranes transverse fibres are vibrated they push the Hair cells
contained within the Organ of Corti up against the Tectoral membrane which causes
electrochemical signals to be sent to the brain through the Auditory nerve to be
interpreted as sound.

Outline the role of sound shadows cast by the human head in the location of
sound.
The main use for a sound shadow that is cast by the Human head is to allow for a
determination of direction and distance that is presented by a foreign object through
sound within their environment. Due to the Structure of the Human Ear it can not move
and bend as that of a Dog’s or a Horses Ear would.
Interpretations of sound come from the use of reflections of sound from the
various structures presented within the Pinna allow for the determination of direction.
Sound the hits the ear at different directions is interpreted and heard by the Ear
differently. Sound that comes from the front of sides of the Ear is enhanced as they are
directed through the various other structures of the Ear. An almost blind spot is
presented when sound is received from the back of the Ear. Due to its shape and
structure of the Ear the sound from behind it is reduced.
Internet Resources:
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http://www.sapdesignguild.org/editions/highlight_articles_01/images/accomod
ation.png
http://www.skybrary.aero/images/thumb/500045-fx6.jpg/300px-500045-fx6.jpg
micro.magnet.fsu.edu/.../refraction.html
http://clearvieweye.net/blog/wp-content/uploads/2010/01/accom.gif
http://www.austincountyeye.com/graphics/Hyperopia_austin_county.jpg
http://www.roseopticals.com/images/youreye/Myopia_lg.jpg
http://www.daviddarling.info/images/corrective_lenses.jpg
http://jirehdesign.com/images/illustrations/SUCA0025.jpg
http://visione360eye.com/images/cataract_20example520.jpg
http://www.eyedesignbook.com/ch3/fig3-61retinarods-conesBIG.jpg
http://www.colourtherapyhealing.com/colour/images/rods_cones.gif
http://cas.bellarmine.edu/tietjen/Laboratories/Eye07.gif
http://www.colblindor.com/wp-content/images/Protanopia-Color-Spectrum.jpg
http://www.colblindor.com/wp-content/images/tritanopia-color-spectrum.jpg
http://micro.magnet.fsu.edu/primer/lightandcolor/images/humanvisionfigure7.j
pg
http://www.uscities.net/starherbals.com//tango/description/macula.gif
http://www.biology-resources.com/images/compound-eye-big.jpg
http://thumbs.dreamstime.com/thumb_381/1238427887gL8855.jpg
http://www.colorado.edu/intphys/Class/IPHY3730/image/figure8-14.jpg
http://www.hhmi.org/images/bulletin/sept2005/inner-ear.jpg
http://www.williams.edu/astronomy/Course-Pages/111/Images/ems.jpg
http://micro.magnet.fsu.edu/optics/lightandcolor/images/refractionfigure1.jpg
http://media-2.web.britannica.com/eb-media/03/5703-004-594D0C62.gif
http://www.nei.nih.gov/healthyeyes/eye_images/Normal.gif
http://media-2.web.britannica.com/eb-media/57/72157-035-3A4E50BE.jpg
http://www.impactlab.com/wp-content/uploads/2009/08/honey_bee.jpg
http://starizona.com/acb/ccd/advimages/eye01.gif\
http://www.rpdms.com/satillusion/cones.jpg
http://robpaterson.files.wordpress.com/2009/03/sound_wave.jpg
http://www.teenbuzz.org/decibels.png
http://www.biologycorner.com/anatomy/respiratory/Larynx%20front.jpg
http://www.nlm.nih.gov/medlineplus/magazine/issues/fall08/images/humanear
_anatomy.jpg
http://drharris.ucsd.edu/Portals/0/Eustachian%20tube%20cropped%20(NLM).jp
g
http://misclab.umeoce.maine.edu/boss/classes/SMS_491_2003/sound/Dusen9_
17.jpg
Book/Text Resources:
 School Text Book
 Cosmos Scientific Magazine: http://www.cosmosmagazine.com/
 Science Magazine: http://www.sciencemag.org/