Bio 161 QUESTIONS AND ANSWERS A+
GRADED
eyeball is located..
in the orbit and connected tothe skull by several external muscles
Three layers of the eyeball
Outer sclera, Middle choroid, Inner retina
Outer sclera
Very tough and strong,protective layer•
At front of eye, becomes clear cornea
Middle choroid
Highly vascular
Inner retina
Location of photoreceptive sensory cells, continuous with optic nerve
Conjunctiva
a thin, transparent membrane thatcovers eyeball anteriorly and lines eyelids
Vitreous humor:
clear gel, fills posterior eyeball
- Gives eyeball its shape
Aqueous humor
- clear fluid, circulates through anterior eyeball (areas anterior to lens)
- Maintains pressure in eye,bathes cells in nutrients
Choroid layer forms two rings of smooth muscle anteriorly
Iris and Ciliary body
Iris
covers part of lens, controls amount of light letinto eye
Ciliary body
attached to lens, controls shape of lens
Dilation
of iris widens pupil to let in more light
Contraction
of iris narrows pupil to let in less light
Ciliary body focuses on what ?
the lens
The iris controls what?
width of pupil (central opening in iris)
Dilation/relaxation of ciliary body
puts tension on lens, flattening it :focus on distant objects
Contraction of ciliary body
relieves tension on lens, allowing it to bulge into round shape: focus on near objects
Rods
GRADED
eyeball is located..
in the orbit and connected tothe skull by several external muscles
Three layers of the eyeball
Outer sclera, Middle choroid, Inner retina
Outer sclera
Very tough and strong,protective layer•
At front of eye, becomes clear cornea
Middle choroid
Highly vascular
Inner retina
Location of photoreceptive sensory cells, continuous with optic nerve
Conjunctiva
a thin, transparent membrane thatcovers eyeball anteriorly and lines eyelids
Vitreous humor:
clear gel, fills posterior eyeball
- Gives eyeball its shape
Aqueous humor
- clear fluid, circulates through anterior eyeball (areas anterior to lens)
- Maintains pressure in eye,bathes cells in nutrients
Choroid layer forms two rings of smooth muscle anteriorly
Iris and Ciliary body
Iris
covers part of lens, controls amount of light letinto eye
Ciliary body
attached to lens, controls shape of lens
Dilation
of iris widens pupil to let in more light
Contraction
of iris narrows pupil to let in less light
Ciliary body focuses on what ?
the lens
The iris controls what?
width of pupil (central opening in iris)
Dilation/relaxation of ciliary body
puts tension on lens, flattening it :focus on distant objects
Contraction of ciliary body
relieves tension on lens, allowing it to bulge into round shape: focus on near objects
Rods
