Biology Questions and Answers
Visual System
- What is vision? Why is
vision important for life on
earth?
Vision is thto perceive, to e ability of some distinguish and toliving b eings
interpret luminous stimuli.
Vision is important on earth mainly in
the terrestrial and in the superficialaquatic habitats because our planet is (^)
intensely exposed to sunlight and thus
light and colors bfactors of objects present iecome distingn theuishing
environment, even at distance. distinction provided new survivalThis
strategies for the organisms, new
protection mdangers, new ways to fechanisms against extind food and toernal
communicate with other individuals,
new types of courtinbehaviors, etc. That is, it createg and reproductiond new
possibilities of interaction with the
surrounds anexplore new ecological nichd increased capacityes. to
- How does photosensitivity
in cnidarians, annelids and
worms differ from insects,
cephalopods and vertebrates?
In the first mentioned group of animalsthere are photoreceptor cells organized (^)
in ocelli or diffusely dispersed in the
body. These animalsimages. do not form
In the animals of the second group the
photoreceptor cellssophisticated structures, are part of more the eyes, able (^)
to form images and to send them to the
nervous system.
- What are the structures
that compose the human
vision apparatus?
The organs of the human visual
apparatus arnerves and the visual areas oe the eyes, the opticalf the brain (^)
(locatehemispheres).d in the occipital lobes of both
- What are the main
structures of the human eye?
The main structures oare the cornea, the iris, the pupil, thef the human eye
ciliary muscles,the retina (the space b the crystallineetween the lens an d
crystalline lens and the retina within the
eyeball is filled with vitreous humor). - What is the function of the
iris and of the pupil?
The iris works like the diaphragm of aphotographic camera since it has
muscles that contract or relax varying
the pupil diameteintensity heightens the parasympathr. When the luminoeticus (^)
nervous system commands the
contractionshortage of light the sympath of the pupil; when there isetic
nervous system stimulates the dilation
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