The eye Flashcards
eyelid
fold of skin which covers the eye. It cleaning and protecting the eye
pupil
hole in the middle of the iris. it allows light to enter the eye
sclera
white part of the eye made of tough collagen fibres. it provides protection and support
iris
ring of muscles around the pupil coloured which provides eye colour. controlling the amount of light entering the eye
ciliary body
attached to the underside of the lens. producing aqueous humour and helping with focusing by altering the shape of lens
cornea
the transparent covering on the eye. protecting the eye; helping converge bend and join light rays that enter the eye
lens
transparent, flexible, and can change shape due to the ciliary muscles. focusing the light onto the retina and focusing on objects
aqueous humour
found behind the cornea. helping to keep its round shape; providing nutrients to the cornea and lens
media rectus muscles
found on the medial side of the eye. helping orientate the pupil towards the centre of the body
choroid
a layer of blood vessels with a black pigment. nourishing the eye and absorbing light
optic nerve
bundle of fibres. relaying information from the retina and fovea to the brain
microscopy
light - a light microscope uses light and different lenses to magnify objects to allow the image to be seen through an eyepiece
electron-electron microscopes use electrons instead of light to produce detailed images with a high magnification
magnification
image size/actual size
staining a sample
chemical = gram = different types of bacteria = +red -violet
chemical = eosin = red blood cells and cell membrane pink
chemical = iodine = starch -blue black
chemical = methylene = nuclei and chromosomes - blue
the vision process
Light rays are reflected and focused on the pupil as the enter through the cornea. Muscles in the iris contract or relax to control the amount of light passing through the pupil
Behind the pupil in the lens which reflects the light more so it is focused on the retina
The photoreceptors in the retina respond to the energy from the light and generate action potentials which are sent along the optic nerve to the brain for processing
predators
binocular vision this creates a 3D image because of the overlap
eyes are on the front of the face narrow field of vision
have better depth perception than prey
prey
monocular vision each eye works independently and only overlaps a small area
the eyes are positioned on the front of the head wider field of vision - good for detecting predators
poor depth perception
photoreceptors in the eye
rods - seeing in low light
cons - seeing in a lot of light
adaptations to see in the dark
tapetum lucidum - a layer that contains reflective pigment which helps animals see in low light
slit pupil as they are easier to contract than round
a much higher concentration of rod cells in the retina
much larger eyes which have wider pupils this allows them to capture more light
vitreous humour
located behind the lens. giving the eyeball its shape
lateral rectus muscle
found on the lateral side of the eye. helping orientate the pupil away from the centre of the body
optic disc
a blind spot where there are on photoreceptors. where the optic nerves leave the eye
tapetum lucidum
is layers of extra tissue behind the retina. reflects light back through the retina.
reflects light back through the retina
therefore increases light for photoreceptors
fovea
spot located in the macula which has a high density of cone cells
- giving sharp central vision light is focused onto this spot by the lens
