Sensory System Flashcards
Does pressure activate an ionotropic or metabotropic receptor?
ionotropic
does taste/smell activate an ionotropic or metabotropic receptor?
metabotropic
does light/vision activate an ionotropic or metabotropic receptor
metabotropic
what is a receptor potential
a change in mem pot of a sensory cell in response to a stimulus
function of merkel discs
at surface, adapt slowly, provides cont info
function of meissner’s corpuscles
at surface, very sensitive and adapt rapidly
function of Ruffini corpuscles
deeper, adapt slowly, sense low freq vibrations
function of pacinian corpuscles
deeper, adapt quickly and sense high freq vibrations
where are hair cells in the ear found and what is their function
cochlea; respond to vibration induced by sound
function of rhodopsin
- highly conserved among animals and some plants
- a family of photo receptors
- composed of retinal pigment bound to opsin protein (a 7 transmembrane domain protein)
- opsin is sim to GPCR, but ligand is the conformational change of retinal in light
detail conformational change of retinal
light induces retinal to change from 11-cis to All-trans form which induces a change in conformation of opsin
photo-excited rhodopsin triggers cascade that changes membrane pot of photoreceptor cells
function of ommatidium
- optical units found in compound eyes of invertebrates
- each has a lens that directs light onto photoreceptor cells called retinula cells
- retinula cells contain rhodopsin and their axons comm. w/ nervous system
- the smaller, the better the resolution
functions of rods
- in vertebrates
- modified neuron w/ outer segment, inner segment, and synaptic terminal
- inner segment: nucleus & mito
- outer segment: photoreception in membrane-bound discs packed w/ rhodopsin
- hyperpolarizes in light
- depolarizes in dark
- more sensitive to low intensities of light–> high sensitivity B&W vision
detail how vision works in vertebrates?
in dark, rod cells are depolarized to steady state (~-35mv)
when rhodopsin absorbs light, it gets photoexcited and activates a G protin called TRANSDUCIN
when transducin is active, cGMP phoshphodiesterase is active so cGMP–> GMP
in dark, cGMP keeps Na+ open, and in light, less cGMP = closed Na+ -> rod cell now hyperpolarized
which cell are the input and output to bipolar cells in the retina?
input from photoreceptor cells, output to ganglion cells
What do the depolarized photoreceptors release as a NT to the bipolar cells in the dark
glutamate
What happens to glutamate when there is light?
PR hyperpolarize and stop releasing NT
What happens to glutamate in the dark once released from PR cells?
some bipolar cells have metabotropic receptors that open Cl- channels–> Cl- enters so hyperpolarized
What happens in the light when glutamate is not released?
Cl- remain closed, depolarized bipolar cell to threshold, and fires AP to ganglion cells which fires another AP to optic nerve to brain
T/F: depolarization of PR cells release bipolar cells from inhibition
F: hyperpolarization
What happens to the shape of the lens as it is looking at an object close vs far away
close: lens round out
far: lens stretches out
what is the most sensitive area for resolution and has the highest density of PR?
fovea
what causes poor vision
change in eyeball shape that puts focal length outside the range the lens is able to focus
what is presbyopia
lens becoming less elastic w age–> reading glasses
