ANA 442 Exam 2 Questions and Answers
association cortex - ✅cortical area that integrates information for multiple sensory
systems
blue on bipolar cell - ✅an on-bipolar cell selectively connects to S cones, activated by
short WL light and is inhibited by longer WL light
Center-surround - ✅A property of a visual system neuron's receptive field in which light
in the receptive field center and light just outside of the receptive field center are
antagonistic. The concept has also been extended beyond the visual system.
chromophore - ✅The light-absorbing portion of a molecule.
color-opponent RGC - ✅A retinal ganglion cell that differentiates signals from cones
with distinct spectral sensitivities. The blue-yellow opponent RGC (in all mammals)
differentiates short- and longer-wavelength light signals; the green-red opponent RGC
(in trichromatic primates) differentiates two long-wavelength light signals.
GCAP - ✅A calcium-binding protein which in its calcium-free form binds to and
activates guanylate cyclase.
Guanylate Cyclase - ✅An enzyme that produces cGMP from GTP.
horizontal cells - ✅An inhibitory neuron in the vertebrate retina whose actions influence
the signals that are transmitted from the photoreceptors to the bipolar cells.
midget ganglion cells - ✅A retinal ganglion cell with a small receptive field used for
high-acuity vision and green-red color vision.
OFF bipolar - ✅A bipolar cell that expresses ionotropic glutamate receptors and is
depolarized by glutamate release from photoreceptors. Its membrane potential changes
follow the sign of photoreceptors such that it is hyperpolarized by light
ON bipolar - ✅A bipolar cell that expresses metabotropic glutamate receptors and is
inhibited by glutamate release from photoreceptors. Its membrane potential changes
are opposite in sign to those of the photoreceptors such that it is depolarized by light.
opsin - ✅A member of a family of G-protein-coupled receptors expressed in
photoreceptors of multicellular organisms, it is associated with retinal and converts
photon absorption to the activation of a trimeric GTP-binding protein. In microbes, it is a
member of light-induced channels or pumps, which are not G-protein-coupled receptors.
, outer segment - ✅A cytoplasmic extension of a rod or a cone, it contains a highly
specialized photon detection apparatus made of tightly stacked membrane disks
enriched in opsins.
photoreceptors - ✅A cell that converts light into electrical signals.
phototransduction - ✅The biochemical reactions triggered by photon absorption.
receptive field - ✅In the visual system, the area of the visual field that influences the
activity of a given neuron. In the somatosensory system, the area of the body where
stimuli can influence the firing of a neuron.
recovery - ✅The process by which light-activated photoreceptor cells return to the dark
state.
RGS - ✅A protein that acts as a GTPase activating protein for a trimeric GTP-binding
protein.
retina - ✅A layered structure at the back of the vertebrate eye made of five major
neuronal types (photoreceptors, horizontal cells, bipolar cells, amacrine cells, and
retinal ganglion cells) and support cells. Collectively, these cells convert light into
electrical signals, extract biologically relevant signals from the outputs of
photoreceptors, and transmit these signals to the brain.
retinal - ✅A chromophore covalently linked with an opsin, it changes its configuration
after photon absorption.
retinal ganglion cell - ✅The output cell of the retina that transmits information from the
eye to the brain.
rhodopsin - ✅photosensitive molecule in the rod consisting of opsin covalently attached
to retinal, a chromophore derived from vitamin A.
spectral sensitivity - ✅The relationship between a response (e.g. of a photosensitive
cell or molecule) and the wavelength of the stimulus light.
transducin - ✅A trimeric GTP-binding protein that links light-activated rhodopsin (or
cone opsin) to phosphodiesterase activation in vertebrate photoreceptors.
umvelt - ✅within our realm of perception
trichromat - ✅Organisms that have three different cones for color vision—the S-cone,
M-cone, and L-cone
Why do some animals have such a keen sense of smell while others do not? - ✅Smell
is primarily dependent on the number of odorant receptors coded for in your genome.
association cortex - ✅cortical area that integrates information for multiple sensory
systems
blue on bipolar cell - ✅an on-bipolar cell selectively connects to S cones, activated by
short WL light and is inhibited by longer WL light
Center-surround - ✅A property of a visual system neuron's receptive field in which light
in the receptive field center and light just outside of the receptive field center are
antagonistic. The concept has also been extended beyond the visual system.
chromophore - ✅The light-absorbing portion of a molecule.
color-opponent RGC - ✅A retinal ganglion cell that differentiates signals from cones
with distinct spectral sensitivities. The blue-yellow opponent RGC (in all mammals)
differentiates short- and longer-wavelength light signals; the green-red opponent RGC
(in trichromatic primates) differentiates two long-wavelength light signals.
GCAP - ✅A calcium-binding protein which in its calcium-free form binds to and
activates guanylate cyclase.
Guanylate Cyclase - ✅An enzyme that produces cGMP from GTP.
horizontal cells - ✅An inhibitory neuron in the vertebrate retina whose actions influence
the signals that are transmitted from the photoreceptors to the bipolar cells.
midget ganglion cells - ✅A retinal ganglion cell with a small receptive field used for
high-acuity vision and green-red color vision.
OFF bipolar - ✅A bipolar cell that expresses ionotropic glutamate receptors and is
depolarized by glutamate release from photoreceptors. Its membrane potential changes
follow the sign of photoreceptors such that it is hyperpolarized by light
ON bipolar - ✅A bipolar cell that expresses metabotropic glutamate receptors and is
inhibited by glutamate release from photoreceptors. Its membrane potential changes
are opposite in sign to those of the photoreceptors such that it is depolarized by light.
opsin - ✅A member of a family of G-protein-coupled receptors expressed in
photoreceptors of multicellular organisms, it is associated with retinal and converts
photon absorption to the activation of a trimeric GTP-binding protein. In microbes, it is a
member of light-induced channels or pumps, which are not G-protein-coupled receptors.
, outer segment - ✅A cytoplasmic extension of a rod or a cone, it contains a highly
specialized photon detection apparatus made of tightly stacked membrane disks
enriched in opsins.
photoreceptors - ✅A cell that converts light into electrical signals.
phototransduction - ✅The biochemical reactions triggered by photon absorption.
receptive field - ✅In the visual system, the area of the visual field that influences the
activity of a given neuron. In the somatosensory system, the area of the body where
stimuli can influence the firing of a neuron.
recovery - ✅The process by which light-activated photoreceptor cells return to the dark
state.
RGS - ✅A protein that acts as a GTPase activating protein for a trimeric GTP-binding
protein.
retina - ✅A layered structure at the back of the vertebrate eye made of five major
neuronal types (photoreceptors, horizontal cells, bipolar cells, amacrine cells, and
retinal ganglion cells) and support cells. Collectively, these cells convert light into
electrical signals, extract biologically relevant signals from the outputs of
photoreceptors, and transmit these signals to the brain.
retinal - ✅A chromophore covalently linked with an opsin, it changes its configuration
after photon absorption.
retinal ganglion cell - ✅The output cell of the retina that transmits information from the
eye to the brain.
rhodopsin - ✅photosensitive molecule in the rod consisting of opsin covalently attached
to retinal, a chromophore derived from vitamin A.
spectral sensitivity - ✅The relationship between a response (e.g. of a photosensitive
cell or molecule) and the wavelength of the stimulus light.
transducin - ✅A trimeric GTP-binding protein that links light-activated rhodopsin (or
cone opsin) to phosphodiesterase activation in vertebrate photoreceptors.
umvelt - ✅within our realm of perception
trichromat - ✅Organisms that have three different cones for color vision—the S-cone,
M-cone, and L-cone
Why do some animals have such a keen sense of smell while others do not? - ✅Smell
is primarily dependent on the number of odorant receptors coded for in your genome.
