Task 2: The Retina Flashcards
Visible light
energy within the electromagnetic spectrum that humans can perceive
Electromagnetic spectrum
continuum of electromagnetic energy that is produced by electric charges and is radiated a waves
Wavelength
the distance between peaks of electromagnetic waves, associated with different colours of spectrum
blue = 400 nanometers red= 700 nanometers
Light is reflected from objects to the ___ and is focused by the ___ and ___ to form sharp images on the ____
pupil, cornea, lens, retina
Where does light enter the eye?
cornea
How much focusing power does the
a) cornea
b) lens
have
a) 80%
b) 20%
Why is the cornea transparent?
no blood vessels therefore photons
Why is the lens transparent?
no blood supply
What does the ciliary muscle due?
changes the shape of the lens to adjust the eyes focus by increasing the curvature of the lens (this process is called accommodation)
a) Define accommodation
b) What does accommodation prevent?
a) change in len’s shape that occurs unconsciously when ciliary muscles tighten and increase curvature of lens
b) blurring
Define retina
network of neurons that covers the back of the eye and contains photoreceptors responsible for receiving image froms lens and sending it to the brain via optic nerve
What are photoreceptors?
rods and cones containing light-sensitive visual pigments, transduces light energy to neural energy
What part of the eye brings light into focus?
retina
What is the role of the retina?
to detect light and communicate to brain the aspects of light related to objects in the environment
What part of the eye gives it its colour?
iris
What does the iris do?
the iris controls the size of the pupil and the amount of light that reaches the retina, attached to ciliary muscles
Pupillary light reflex
automatic expansion or contraction when level of light increases or decreases, that allows either more or less light to enter the eye
What happens to the lens and pupil when the ciliary muscle
a) contracts
b) relaxes
a) lens thickens for close vision, pupil small for less light
b) lens thins for distant vision, pupil large for more light
Role of pupil
allows light in to reach lens
Aquous humor
a) define
b) function
a) fluid filled space behind cornea
b) supply of O2 and nutrients to cornea and lens and; removing waste from cornea and lens
Vitreous humor
a) define
b) function
a) gel-like fluid that fills the vitreous chamber
b) light refractor - to reach retina, light goes through vitreous chamber, where it is refracted by vitreous humor
What is the longest part of the journey through the eyeball for light?
vitreous chamber
Fovea
a) location
b) function
a) part in the center of the retina
b) - responsible for producing the highest visual acuity and point of fixation - seeing fine detail, reading, identifying objects
Light energy from stimulus is converted into
neural energy