NEUROBIO EXAM 3
only ________ cells fire action potentials
ganglion
in central retina, few photoreceptors send info to a
ganglion cell (high resolution)
Refraction by the cornea
refractive power of cornea is greater than the lens
Accommodation
refractive power of lens can be changed (Added)
suprachiasmatic nucleus of hypothalamus
regulates most circadian rhythms if body (sleep, wakefulness)
brainstem
related to alertness and attentiveness
Photoreceptors
respond to light
2 types of photoreceptors in the retina
rods and cones
Cornea
The clear tissue that covers iris
Sympathetic neurons->
Dilator pupilae (radial) muscles -> incr pupil size (Dilation)
Hot color
lower frequency (lower energy)
3 ossicles in the middle ear
malleus (hammer), incus (anvil), stapes (stirrup)
motor proteins (prestin)
membranes of outer cells hair cells can change the cell length in response to sound
uvea
middle coat of the eyeball; includes the iris-pupil, ciliary body, and choroid
Conjunctiva
mucous membrane that lines the eyelids and outer surface of the eyeball
Phototransduction occurs in
outer segment of rods and cones
photoreceptor structure
outer segment(discs containing photopigments), inner segment(cell body), synaptic terminal
ventral stream
perception of visual motion and visual control of action
ventral stream
perception of visual world and recognition of objects- shape, color, texture
Horizontal cells
receive input from the photoreceptors and project to other photoreceptors and bipolar cells
iso frequency bands
contain neurons that have similar characteristic frequencies frequencies
scala media (cochlear duct)
continuation of membranous labyrinth into cochlea
Phototransduction
conversion of light energy recieved by photoreceptors into changes in membrane potential (electrical signals)
Sclera
-white of the eye -dense connective tissue -covers entire eyeball EXCEPT cornea
Structures in retina
Macula lutea, Fovea centrails, Optic disc, vitreous humor
primary visual corte
80% of excitatory synapses onto LGN neurons
Visual acuity
-Ability to distinguish 2 nearby points -Depends on photoreceptor density in retina and precision of refraction
lateral geniculate nucleus (LGN)
A structure in the thalamus, part of the midbrain, that receives input from the retinal ganglion cells and has input and output connections to the visual cortex.
choroid
-Lines most of the internal surface of the sclera. -Highly vascularized: Provide nutrients to the posterior surface of the retina -Contains melanocytes: Melanin pigments absorb stray light rays and prevent reflection and scattering of light in the eyeball.
ciliary body
-anterior portion of vascular layer -melanocytes: dark color -consists of ciliary processes and ciliary muscles
scala vestibuli
-begins at vestibular (oval) window -filled with perilymph
ciliary muscle
-circular smooth muscle that contracts to control the shape of the lens -adapts lens for near and far vision (accommodation)
Iris
-colored portion of eye- between cornea and lens, attached ciliary process -Melanocytes -Regulates amount of light entering eye
eustachian tube (auditory tube)
-connects meddle ear with nasopharynx -controls pressure in middle ear, making it equal with atmospheric pressure
ciliary processes
-contain capillaries that secrete aqueous humor. -Zonular fibers (suspensory ligaments) extend from ciliary processes and attach to lens
structure of fovea centralis
-the ganglion cell layer and the inner nuclear layer are displaced laterally -light hits photoreceptors directly
superior colliculus
-dorsal midbrain -involved in eye + head movements for tracking moving images and scanning stationary images
scala tympani
-ends at cochlear (round) window -filled with perilymph
Optic disc
-exit site of optic (II) nerve -blood vessels enter eyeball -blind spot
central vision
-greater visual acuity at photopic light levels(daylight) -blind at scotopic light levels (dim light) -better in discriminating colors
Fovea centrails
-highest visual acuity (Resolution) -contains only cones
peripheral vision
-more sensitive to scotopic light levels
Rods
-more than 1000x more sensitive than cones -vision in scotopic conditions(dim) -black/white vision
pretectum in midbrain
-regulation of pupil size (light reflex) -light evoked brinks -REM sleep triggering
middle ear
-small air filled cavity -3 ossciles
cones
-stimulated in photopic conditions (brighter light) -produce color vision -3 types (blue,green,red cones)
wall of the eyeball
1. fibrous layer 2. vascular layer- uvea 3. inner layer- retina
3 scalae of cochlea
1. scala vestibuli 2. scala media 3. scala tympani
Refraction
Bending of light rays (cornea, lens)
inner ear (labyrinth)
Bony labyrinth - cavity consisting of semicircular canals, vestibule and cochlea. Membranous labyrinth - walls and sacs within the bony labyrinth. Membranous labyrinth- inside bony, receptors for hearing and equilibrium
tastants
Chemicals that stimulate gustatory receptor cells
sour
Hydrogen
diopter
reciprocal of focal distance; measurement of refractive power
fungiform papillae
Mushroom-like protuberances often containing taste buds and located on the sides and tip of the tongue.
Pupil constricts as
sphincter pupilae muscles of iris contract (parasympathetic)
fibrous layer
Outermost layer; dense avascular connective tissue (Sclera anf Cornea)
Which of the following is the correct sequence of sound wave transfer in the inner ear?
Oval window ---> Scala vestibuli --> Helicotrema --> Scala tympani ---> Round window
sequence of visual information transfer in the retina
Photoreceptors --> Bipolar cells --> Ganglion cells
Transduction
conversion of one form of energy into another. In sensation, the transforming of stimulus energies, such as sights, sounds, and smells, into neural impulses our brains can interpret.
salty
Sodium
Reflection
The bouncing back of a wave when it hits a surface through which it cannot pass.
Parasympthatetic neurons ->
Sphincter pupillae (circular) muscles -> decreases size of pupil (Constriction)
Attenuation reflex
adapts ear to loud sounds, protects inner ear, enables discern high frequency sounds more easily
dorsal stream
analysis of visual motion and the visual control of action
receptive field
area of retina where light would change firing rate of a neuron
Pupillary light reflex
autonomic reflex
outer hair cells amplify movement of
basilar membrane during low intensity sound stimuli- cochlear amplifer
iso high frequencies
caudal medial
when photoreceptor is at rest (in the dark)
cell is relatively depolarized
odorants
chemicals that bind to olfactory receptors and stimulate olfactory sensory neurons
Fovea centrailis contains
cones
constriction of pupils
decreases amount of light entering the eye
contraction of ciliary muscle
decreases tension in zonular fibers, lens becomes rounder/thicker, increase in refractive power
Pupil dilates as
dilator pupilae muscles of iris contract (sympathetic)
Focal Distance
distance from refractive surface to point where parallel light rays converge
Light
electromagnetic radiation that is visible to our eyes
viterous humor
fills space between retina and lens
auditory and vestibular systems use ____ cells as sensory receptors
hair cells
Cool color
high frequency (higher energy)
Pupil
hole in center of iris
activation of photoreceptor by light causes
hyperpolarizing receptor potential
more photopigments are bleached
incr light level
in the peripheral retina, many photoreceptor cells provide
input to a ganglion cell (detection of dim light)
bitter
ions (K+)
vallate papilae
large and few, posterior dorsal V, most buds within walls
bipolar cells receive direct inputs from photoreceptor cells
light-> photoreceptor cells -> bipolar cell
bipolar cells receive indirect inputs from photoreceptor cells
light-> photoreceptor cells -> horizontal cells-> bipolar cell
Retinal Info Processing
light-> photoreceptors -> bipolar cells -> ganglion cells -> brain
foliate papillae
located on lateral aspects of posterior tongue
optic (II) nerve axons from nasal retina project to
opposite side of brain (contralateral projection)
pathway of conscious visual perception
optic (II) nerve -> optic chiasm -> optic tract -> lateral geniculate nucleus of thalamus -> optic radiation -> primary visual cortex in occipital lobe of cerebum
rods are found mainly in
peripheral retina
intermediate frequencies
phase locking and tonotopy
outer ear
pinna (captures sound waves) and auditory canal (transmits sound to tympanic membrane)
receptive field center
provides a direct input from the photoreceptors to the bipolar cells
receptive field surround
provides indirect input from photoreceptors to bipolar cells via horizontal cells
Amacrine cells
receive input from bipolar cells and project to ganglion cells, bipolar cells, and amacrine cells
iso low frequencies
rostra/lateral
axons from temporal retina project to
same side of brain (lpsilateral projection)
we cannot perceive color differences at
scotopic light levels
gustation
sense of taste
speical senses
smell, taste, sight, hearing, balance
sweet
sugars
basic tastes
sweet, sour, salty, bitter, umami
chemical senses
taste and smell
gustatory receptors cells exist in the ___ and contain receptors for ____
taste buds; tastants
Frequency
the number of complete wavelengths that pass a point per second
Absorption
the transfer of light energy to particles or surface (color)
semicircular canals
three fluid-filled canals in the inner ear responsible for our sense of balance
macula lutea
yellow spot at posterior center of retina and relative absence of large blood vessels
high frequiencies
tonotopy
Visual field
total amount of space that can be viewed by retina when the eye is fixated straight ahead
auditory ossicles
transmit sound vibrations from tympanic membrane to oval window
phase locking
very low frequencies
electromagnetic radiation
wave of energy