5.1 Causes of Disorders Flashcards
What 3 sections is the ear composed of
The outer layer (pinna and ear canal)
The middle ear (ossicles and ear drum)
The inner ear (the cochlea and auditory nerve and the brain)
What does the ear drum do when sound enters the ear in waves
vibrates
Why does conductive hearing loss occur
when there is a damage to the outer or middle ear, resulting in ineffective sound transfer
What may be the cause of conductive deafness
An ear infections, otosclerosis (abnormal bone growth in ear) or perforation of the ear drum
What may the cause be of sensorineural hearing loss
occurs when there is a damage to the inner ear. Sound may arrive at the cochlear, but is not properly passed on to the auditory nerve, or this may be damaged itself
may be congenital
or other factors such as age, gender, noise exposure etc
hearing loss may be a combination of both …
conductive and sensorineural
where does light firstly enter the eye
the cornea, a clear curved ‘window’ on the front of the eye
What does the cornea do
refracts light through the pupil, an opening at the front of the eye, the width of which is controlled by the movement of the iris
What can pupils do
Able to dilate and contact, the shape of the iris changing how much light enters the eye
What does the lens do
it is a curved, flexible structure which focuses light by shortening and lengthening its width
what is the globe of the eyeball filled with
vitreous gel
a dense transparent substance that gives the eye its spherical shape whilst still allowing light to be transmitted to the back of the eye
Where do light rays come too
focal point
where the image is focused, at the retina in the back of the eye
what cells is the retina composed of
rods and cones
these cells enable light energy to be converted into electrical impulses
which send the message onto the optical nerve and through the brain for processing
Refractive errors
occur when the eye does not focus light properly, due to incorrect shaping of the cornea
Myopia (or near sightedness)
Occurs when the cornea is too curved or the eyeball is too long, resulting in light refracted at an angle which places the focal plane in front of the retina.
far away objects a blurry
