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105 Cards in this Set
- Front
- Back
Light is defined by
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what we can percieve
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Radiometric light is measured by
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electromagnetic radiation
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The wavelength of the visible spectrum is between
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400-700nm
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A directional radiometric measurement is
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radiance
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A non-directional radiometric measurement is
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irradiance
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Three types of measurements we might take when studying the effects of light
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Behavioral, electrophysiological, biochemical
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A directional photometric measurement is
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luminance
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A non-directional photometric measurement is
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illuminance
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A graph that might be useful in behavior with light is
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a fluence:response curve
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A microspectrophotometer tests
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light absorbance
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What kind of knockouts are best for behavior?
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conditional
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What is a transgenic animal?
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when a gene is added, often from a different organism.
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How does one create a behavioral action spectrum?
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Generate a fluence:response curve for each wavelength
Set a criterion response Plot the inverse (normalized) |
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Two dynamic components of the visual system are
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iris, lens (both accomodate)
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When energy increases
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wavelength decreases and frequency increases
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A function of oil droplets is to
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Tighten the spectral sensitivity, disambiguates signal.
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Two functions of the retinal pigment epithelium are
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Phagocytosis, regeneration of rhodopsin from all-trans to 11-cis
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The tapetum lucidum is
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A reflective component that boosts light
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Other areas that are light-sensitive in some non-mammalian animals are
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The parietal and pineal, melanophores in frogs
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joules/sec/cm2 or watts/cm2 are what kind of measurements?
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Radiometric
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lumens/cm2 is what kind of measurement?
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Photometric
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Photopic is what kind of vision?
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Daytime, cones
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Scotopic is what kind of vision?
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Nighttime, rods
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When working with animals, we use ______________ measurements
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Radiometric
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What percentage of animals have eyes, light sensing organs, or none of the above?
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1/3
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How many phyla have eyes?
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6 of 33
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three types of optical systems are
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Shadows, refracted, reflected
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Limited number of eye types may be due to
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The physical constraints of light:
Intensity, wavelength, polarization |
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Evolution of eyes from ___ to___ to _____ or _____ th _____
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spot to cups to duplication of cups or photoreceptors then accessory organs such as lenses, irises, retinas, pupils, ommatidia
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Eye cups allow us to know what?
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The direction of light
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What is Rhodopsin?
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A heterotrimeric g-protein coupled receptor
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What happens to All-trans retinal?
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It gets transported to the RPE
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What is the visual cycle?
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All-trans --> Alcohol --> Aldehyde --> 11-cis
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Scallops and lobsters use what kind of eye?
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Reflected light
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Why is an eye cup important?
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Position of light
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how many subtypes of eyes are there?
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8
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What kind of an eye is like a pinhole camera?
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A shadow-detecting eye
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Basic ciliary
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Rhodopsin
Transducin PDE changes cGMP to GMP Channels close (Hyperpolarization) |
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Basic Rhabdomeric Tranduction includes:
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Rhodopsin
Gq PLC hydrolyzes PIP2 to IP3 DAG Channels open (Depolarization) |
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What is considered the "master eye gene?"
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PAX6
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In vertebrates, how is the lens formed?
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It is induced
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What is the ortholog of Pax6 in the fly?
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eyeless
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What is aniridia caused by?
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A mutation in PAX6
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With PAX, the paired domain is involved in what?
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Pigmentation
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With PAX, the homeobox domain is important in
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Expression of photopigment and anterior eye (lens)
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Arguments for monophyletic origins of eyes
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PAX genes
Opsins are universal rhabdomeric and ciliary are in both types of eyes. |
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What is important regarding the organ of hesse?
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Argument against monophyletic origins
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What is the basic unit that is used in all eyes?
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Opsins
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What kinds of opsins are only in the animal kingdom
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rhodopsin 2
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What are lenses made of?
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Crystallins. They are proteins.
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How many crystallins are there?
Name 1 |
11
Lactose dehydrogenase |
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How many crystallins are found in all vertebrates?
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3
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Why use enzymes to make a lens? (2 reasons)
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Increases a buildup of proteins in one place.
Lens must be tightly regulated, controlled. |
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Arguments for Polyphyletic origins of eyes
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Organ of hesse
Molecular level of opsins shows difference Abundance of crystallins |
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How does the lens avoid scattering light?
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Gradient densities manipulate refractions
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Bivalves are a good example of what kind of eyes?
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Reflective and shadow eyes
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Cephalopods are good examples of what kind of eyes?
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Chambered refractive (rhabdomeric) eyes
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If light is reflected on a concave or convex surface, at a 20 degree angle, what angle is it reflected at?
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20 degrees
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In the pectin, the ciliary photoreceptors are ________
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distal
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Wolf spiders demonstrate
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tapetal structures
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The octopus eye is comprised of ______ photoreceptors.
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Rhabdomeric
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The cod eye is comprised of ________ photoreceptors
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Ciliary
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The white part of the eye is called the
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sclera
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The colored part of the eye is called the
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iris
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The gloopy part inside the eyeball is called the
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vireous
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The octopus eye is comprised of ______ photoreceptors.
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Rhabdomeric
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The cod eye is comprised of ________ photoreceptors
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Ciliary
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The white part of the eye is called the
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sclera
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The colored part of the eye is called the
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iris
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The gloopy part inside the eyeball is called the
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vireous
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The octopus eye is comprised of ______ photoreceptors.
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Rhabdomeric
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The cod eye is comprised of ________ photoreceptors
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Ciliary
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The white part of the eye is called the
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sclera
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The colored part of the eye is called the
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iris
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The gloopy part inside the eyeball is called the
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vireous
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The two parts of the eye that feed the retina are called
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the choroid and vitreous
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choroid capillaries do what
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nourish, fenestrate
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3 classes of interneurons are
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horizontal cells, bipolar cells, amacrine cells
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What are the layers in order?
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Choriocapillaris
RPE Outer nuclear Outer synaptic Inner Nuclear Inner Synaptic Ganglion Layer Muller Cells |
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What are the parts of a photoreceptor? (4)
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Outer segment
Inner Segment Nucleus Synaptic Terminal |
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Pedicles belong to
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Cones
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Spherules belong to
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Rods
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Cones terminate in the
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Outer aspect of the outer plexiform layer
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Explain the phototransduction cascade
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-Light changes 11 cis to all trans
-This changes the conformation of the opsin -This causes the opsin to bind g-protein (transducin) -The transducin Alpha subunit trades GDP for GTP -The transducin alpha activates PDE -PDE causes cyclicGMP to become GMP -cyclicGMP is needed by channels to stay open Channels close, cell hyperpolarizes |
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Horizontal cells reside where?
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outer axis of the inner nuclear layer
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H1 cells receive input from
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rods and cones
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H2 cells receive input from
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just cones
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Horizontal cells are ______ coupled
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electrically coupled
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Bipolar cells come in ___ flavors
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2 (on and off)
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Rods go through what cell to get to ganglion cells
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A2 amacrine cells
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Amacrine cells are located in the
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Inner nuclear layer
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Ganglion cells are located in the
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ganglion cell layer
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Cell layers are
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Outer, inner, nuclear, plexiform, ganglion
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What is transduction?
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The conversion of one form of energy into another
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What is sensory transduction?
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The conversion of energy from the environment into a biologically relevant signal.
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What is our reality based on?
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Our sensory systems
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What sorts of conservation are important vis a vis our senses?
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temporal and spatial
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How many g-protein coupled receptors are olfactory in mice?
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900
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Second-order neurons create what kind of potentials?
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Action. Digital.
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Sensory neurons generally create what kind of potentials?
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Graded. Generator, receptor. Analog.
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AM is like what kind of neuron?
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Primary sensory.
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FM is like what kind of neuron?
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Secondary sensory.
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When is noise not a bad thing?
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In the case of stochastic resonance.
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What are 3 psychophysical methods for determining threshold?
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-Method of constant stimuli
-Method of limits -Method of adjustment |
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Light meters are ____metric
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photo
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