Tags & Description
define sensory transduction.
the process of converting various forms of energy located outside of the body (e.g. light rays, sound waves, mechanical forces, or chemicals) into neural signals
explain how conformation change in retina is responsible for light detection.
rhodopsin molecules in outer segment of a photoreceptor undergoes conformational change when struck by a photon
activation of rhodopsin then activates G-protein transducin --> phototransduction cascade is initiated
classify rhodopsin, transducin, and hyperpolarization as either G-protein couples receptor, G-protein, or downstream effects of G-protein cascade.
G-protein: transducin
G-protein coupled receptor: rhodopsin
G-protein cascade: hyperpolarization
provide examples of how structure informs function in the visual system.
during the G-protein cascade, amplification allows sensitivity to a single photon
describe unequal distribution of rods and cones on the retina and how different photoreceptor densities affect vision.
cones: centralized where you look, low density throughout retina with sharp peak in center of fovea
rods: present at high density throughout retina with decline in fovea
blind spot: no photoreceptors (rods or cones)
trace how objects in visual space are represented in the retina, after the optic chiasm and in the visual cortex (V1).
objects are inverted (both upside down & right/left mirroring)
distinguish the function of the dorsal stream from the ventral stream. evaluate which stream is defective in akinetopsia, prosopagnosia, or a new medical condition.
dorsal stream: localization and action
involves motor/premotor cortex & posterior parietal cortex
damage to dorsal stream can lead to akinetopsia
ventral stream: object identification
involves inferior temporal cortex
damage to ventral stream can lead to prosopagnosia
determine which stimulus would best activate neurons in the fusiform face area.
stimulus with facial characteristics, especially eyes
not species dependent (neuronal activity doesn't differ for varying species)
distinguish how the grandmother cell coding scheme differs from the population coding scheme in use of neurons, efficiency, and accuracy.
grandmother cell coding scheme:
each person has a cell dedicated to recognizing/coding their face
uses more neurons since each person needs their own cell for facial recognition
population coding scheme:
collection of neurons talk to feature detectors (use subsets of cells for different people)
requires more ACTIVE neurons
more efficient
identify what sensory transduction must be deciphered in the auditory system.
convert sounds (specifically pressure waves in the air) located outside of the body into neural signals
provide an example of how structure informs function in the auditory system.
different levels of stiffness along the cochlea make it differentially sensitive to different frequencies of sound
describe the tonotopic map in the cochlea and auditory cortex.
high sound frequencies cause maximal vibrations near the cochlea's base
low pitch sounds cause max vibrations in the cochlea's apex
the tonotopic map is preserved in the auditory cortex (rostral part corresponds to apex; caudal part corresponds to base).
describe the relationship between calcium carbonate crystals and vestibular hair cells to vertigo.
when head moves, calcium carbonate crystals collide with vestibular hair cells --> bends vestibular hair cells, causing cells to depolarize
dislodged calcium carbonate crystals overactivate hair cells
even when head is upright & stationary, calcium carbonate crystals collide w/ vestibular hair cells
the brain receives constant neural impulses that the body is upside down/falling when in actuality the body is stationary
Identify the five basic taste and example of each.
umami (MSG)
bitter (bitter melon)
salt (salt)
sour (lemon)
sweet (cake)
Describe differences, if any, between the expression patterns of taste buds responsible for different tastes.
different taste buds do not have discrete expression patterns (intermixed throughout tongue)
Classify T1R1, T1R2, T1R3, T2R, gustducin, TRP-M5, and TRP-M4 as either G-protein coupled receptor, G-protein, or TRP channel. Recall the order in which they are activated in the gustatory system.
G-protein coupled receptor: taste receptors
umami: T1R1 + T1R3
sweet: T1R2 + T1R3
bitter: T2R
G-protein: gustducin
TRP channel: TRP-M5, TRP-M4
order:
chemical compound (food) enters
molecule binds to G-protein coupled receptor --> initiates signal transduction pathway
at the end of G-protein cascade, TRP-M5 or TRP-M4 channels open
Describe characteristics of TRP channels.
when open, it produces a short depolarization (positive potential)
non-selective cation channels
activated through diverse mechanisms (chemicals, temperature, light, sound, touch)
w/o TRP-M4 or TRP-M5, you would not be able to taste sweet, bitter, or savory
Explain why anosmia is common after car accidents.
anosmia is common after whiplash
delicate olfactory nerves entering vertically though the cribriform plate are severed
Analyze patterns of odorant receptor activation involved in odor detection.
an odor activates a specific combo of receptors
ex: how does someone smell onion odor
a molecule in onions activates a combo of dif receptors
olfactory sensory neurons are activated when receptors on it are activated
olfactory sensory neurons activate a region of the olfactory bulb (responsible for detecting chemicals structurally similar to onion molecule)
Describe the chemotopic map and distinguish it from the retinotopic map, tonotopic map (and homunculus).
chemotopic map: structurally similar odorants stimulate overlapping but distinct domains in the olfactory bulb
retinotopic map = mapping of visual input from retina to neurons
tonotopic map = mapping of auditory input
homunculus = distorted representation of body
Define nociception.
the ability to feel pain, caused by stimulation of a nociceptor
Provide examples of where capsaicin can be found.
capsaicin is the active ingredient in chilli peppers & pepper spray
Classify capsaicin as either a polar or nonpolar substance and apply this knowledge to best extract capsaicin.
capsaicin = nonpolar (hydrocarbon chains)
nonpolar molecules do not dissolve well in polar solutions like water (like dissolves like)
dissolves better in nonpolar solutions like oil
Identify the receptor for capsaicin, classify the receptor under its receptor class, and identify other triggers of this receptor.
capsaicin binds TRPV1 (type of transient receptor potential ion channel)
TRPV1 receptors respond to heat & produce burning pain sensations
TRP channels are gated by temperature & various chemical ligands
Distinguish antagonists from agonists, and apply this knowledge to protection against capsaicin.
agonist: drug that mimics endogenous ligand and activates receptor
antagonist: drug that blocks endogenous ligand or agonists from activating receptor
capsaicin antagonist would be antidote to capsaicin (blocks capsaicin from binding to receptor)
Discern whether a particular input would or would not be able to activate touch receptors.
we detect touch through:
finger position, lateral movement
edges, fine details, points
skin stretch
pressure
light touch
itch
vibration
Describe how touch receptors differ.
touch receptors differ from where they're located in the skin, what touch stimuli activate them, & in their receptive fields
Recall how receptive field size affects touch sensitivity (tactile acuity).
tactile acuity highest when receptive fields are small
Distinguish C fiber and A-delta sensory fibers in conduction speed, thickness, myelination, and usage.
slow C-fibers: thin, unmyelinated neurons; slow conduction velocity & duller pain
fast A-delta fibers: myelinated neurons; fast conduction velocity & sharp initial pain
Apply principles of topographic organization in order to predict body part representation in a homunculus of a novel organism.
spatially adjacent stimuli on sensory receptor surfaces are represented in adjacent positions in the cortex
there is larger representation for skin with smaller receptive fields