ANA 442 Exam 2 (Answered) 2022
Graded A+
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. The larger the number of receptors you have, the more detailed your sense of
smell with be.
Graded A+
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. The larger the number of receptors you have, the more detailed your sense of
smell with be.
