Flashcard Set Preview
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| 1 |
primitive eyes
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Receptors spread diffusely over surface (i.e. skin)
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| 2 |
flat eyes
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Layer of photoreceptive cells, with an underlying pigment to prevent light from bouncing back...
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| 3 |
cup-shapped eyes
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Light strikes the concave (inside) surface of the eye. Some focusing and knowing direction...
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| 4 |
vesicular (with lens)
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Refined version of the cup-shaped eye, with a lens added for focusing. Neurons exit eye...
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| 5 |
concave
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inside the eye, between the light and the receptors (i.e. vertebrates)
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| 6 |
convex
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the outer surface, away from the light source (i.e. cephalopod molluscs)
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| 7 |
convex eyes
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The light strikes the convex surface of the eye. Each receptor has a separate lens.
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| 8 |
What is the structure of a photoreceptor?
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Many layers of pigment-containing membranes, that is arranged so light has to pass through...
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| 9 |
What is another name for microvillar?
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rhabdomeric
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| 10 |
What are microvillar (rhabdomeric) receptors?
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photoreceptors
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| 11 |
What are microvilli? And what is their importance?
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Fine finger-like evaginations of the plasma membrane. Their membranes contain the photopigment.
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| 12 |
What are microvillar (rhabdomeric) photoreceptors made of?
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microvilli
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| 13 |
Explain ciliary photoreceptors. 1) composition 2) when pigment is stored
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Cilium is in this photoreceptor. The photopigment is contained in the membranes of flattened...
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| 14 |
What is the difference between microvillar and ciliary photoreceptors?
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1) the way their membranes are formed and arranged 2) chemical cascade that leads from light...
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| 15 |
Who posses ommatidium?
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annelids, molluscs, and arthropods
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| 16 |
Type of microvillar (rhabdomeric) receptor?
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ommatidium
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| 17 |
What is the job of the corneal lens and the crystalline cone?
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to focus light
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| 18 |
What is the job of the pigment cells?
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shield the ommatidium from stray light
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| 19 |
Which direction does the pigment migrate to increase visual acuity? to increase visual sensitivity?
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A) toward the lensB) away from the lens
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| 20 |
What is the retinula?
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8 sensory cells
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| 21 |
Where is the rhabdomere found and what is it?
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found inside the retinula and it is composed of microvilli
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| 22 |
rhabdome
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total of all rhabdomeres
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| 23 |
What is the importance of the rhabdome?
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It is where the photopigments are contained and is the site of photoreception
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| 24 |
Where is the base of the connecting cilium found?
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In the inner segment
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| 25 |
In a rod, describe the outer segment.
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It contains a stack of flattened vesicles. The vesicles hold the photopigments. Part...
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| 26 |
What is the structural difference between rods and cones?
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The basal end (end near inner segment) of the outer segment of cones is large and cone-shaped
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| 27 |
What are rods used for and what are cones used for?
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The basic mechanism is the same. However, rods are used for night vision (more sensitive)...
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| 28 |
Explain the evolution of photoreceptor types?
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The universal/ever-present use of a common set of control genes in the development of both...
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| 29 |
provide the general outline of photchemistry
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1) light falls on membranes of photoreceptors 2) a change in the potential of the receptor's...
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| 30 |
What is a pigment?
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Colored organic non-polypeptide molecule (chromophore - class of compounds = carotenoids)+...
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| 31 |
carotenoids
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Class of compounds of chromophore, were light is absorbed. Synthesized by PLANTS!
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| 32 |
What is depolarization and hyperpolarization?
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Depolarization- a change in the membrane voltage TOWARD ZEROHyperpolarization- AWAY from ZERO
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| 33 |
depolarization and hyperpolarization verses ommatidia and rods/cones
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depolarization (change in membrane voltage TOWARD ZERO) is ommatidia and hyperpolarization...
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| 34 |
rhodopsin (visual pigment)
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retinal1 (yellowish carotenoid) + opsin (colorless) - found in rods of terrestrial/marine vertebrates...
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| 35 |
Who uses retinal2 as a part of the pigment?
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freshwater fish
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| 36 |
11-cis form for retinal1
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dark-adapted eye
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| 37 |
all-trans form for retinal1
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eye in light
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| 38 |
isomerization
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change from cis to all-trans form
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