Ch. 50 - Sensory & Motor Mechanisms: Photoreceptors and Vision Flashcards
everything vision related you could ever ask for
what are light detecting organs?
a collection of photoreceptors that respond to light and shadow
what are compound eyes?
eyes that sense changes in light at high frequency; have more cones and can thus see more colours
what is a single lens eye?
mammalian eyes with a pupil and layers of photoreceptors, using various methods to focus the lens when needed
what is the structure of the sclera?
the “whites” of the eye - the hard structural framework
what is the function of the sclera?
to provide the shape of the eyeball
what is the cornea?
the cornea is the transparent covering of the eyeball
what is the function of the cornea?
to protect the eye, and refract / bend light
what is the structure of the choroid?
the choroid is a highly vascular pigmented layer, covering much of the eyeball
what is the function of the choroid?
to provide blood supply to the eyeball, and absorb any stray light
what is the structure of the iris?
the iris is a muscular ring with a hole in the middle - the pupil
what is the function of the iris?
to contract or relax, regulating the amount of light that can enter the eyes
what are the ciliary muscles?
a sphincter-like muscular ring around the eyes
what is the function of the ciliary muscles?
to regulate the shape of the lens, and allow the lens to fatten/thicken
what are suspensory ligaments?
bands that regulate the shape of the lens along with the ciliary muscles
what is the function of the suspensory ligaments?
regulate the shape of the lens by…
relaxing: “fattening the lens” [up close vision]
contracting: thinning the lens, distance vision
what is the lens?
a transparent and elastic disc of proteins within the eye
what is the function of the lens?
to refract light into the eye
[refracts light more when thick than flat]
what is the retina?
the part of the eye containing the photoreceptors and other neurons
what is the function of the retina?
to transduce light signals into electrical signals so the brain can understand them
what are the three types of cone cells found in humans?
red, green, and blue
where are cone cells located within the eye?
all cone cells are concentrated in a region called the fovea centralis
what type of vision do cone cells provide?
highly detailed vision - you can’t read this flashcard out of your peripheral vision because there’s no cones there
what are rod cells?
cells that cannot see colour, but assist in night vision and sensing motion in the peripheral vision
how is visual stimuli sent to the brain? (what nerve, what lobe)
the optic nerve sends visual information to the occipital lobe
what happens to vision when the ciliary muscles contract?
the suspensory ligaments relax, causing the lens to thicken = up close vision
what happens to vision when the ciliary muscles relax?
the suspensory ligaments contract, causing the lens to flatten = distance vision
