Chapter 10 Pt. 3 (Part 3) Flashcards
explain how the semicircular canals are able to determine orientation in three different planes? (3)
- each semicircular canal has one ampulla containing hair cells with short-to-long stereocilia
- high [K+] endolymph movement lags behind head movement and displaces stereocilia
- sends signals to afferent neurons
stereocilia bend towards short = high or low AP frequency?
low
stereocilia bend towards long = high or low AP frequency?
high
what do the utricle and saccule use to detect acceleration and gravitational force?
hair cells
what do semicircular canals tell you?
nod up and down yes
shake side to side no
nodding down towards the shoulder
what do utricle and saccule tell you?
going up or down, forward or backwards
how does a sweet receptor work? (in general, then three points)
stimulated by mono or di saccharides binding a receptor
- sweet molecule binds to G-ptn-coupled receptor, G ptn activates adenylate cyclase to make cAMP
- cAMP activates PKA to phosphorylate and close K+ channels
- K+ can’t exit, the taste receptor depolarizes and activates voltage-gated Ca2+ channels to trigger NT release
how does a bitter taste receptor work?
bitter molecule blocks an ionotropic receptor K+ channel and triggers a sour taste
bitter molecule binds to G protein coupled receptor
-produces secondary messenger signaling by IP3
-IP3 binds to Ca+2 channels on smooth ER, internal Ca+2 released that triggers NT release
how does a umami taste receptor work?
4 types of G protein receptors, but that’s all we know
how does a salty taste receptor work?
Na+ and K+ enter through Na+ channels
depolarizes the cell
Ca+2 voltage gated channels open
NTs released
how does a sour taste receptor work?
involves free H+
- H+ enter sour receptor K+ channels and cause them to close
- K+ can’t get out -> depolarization and Ca+2 influx
- NT released
- get an action potential
why is it harder to taste when you have a cold?
cold = increased mucus thickness in the nasal cavity to trap the virus = nerve endings are farther from opening = impacts smell which impacts taste
what is the structure of smell receptors?
olfactory receptors for the same odorant all synapse to the same glomerulus or a few glomeruli. a glomerulus synapses with a mitral cell. mitral cells form the olfactory tract.
how does the olfactory nerve pathway improve the sense of smell?
deliver multiple inputs as a single action potential (makes a stronger signal)
- cast a wider net aka more smells, but end up sending the same number of signals
- all the receptors are for the same thing in a bundle
in olfactory training, a patient deeply inhales each odorant while concentrating on their memory of the corresponding smell. what do you think is happening here?
electrical and chemical synapse keeps the synapse from breaking. similar to speech pathology, it’s better to start these treatments as soon as possible to keep that neural pathway open.
