Chemoreception
Taste (Gustation) -dep smell (Olfaction) - dep
receptor ● modified epithelium cells ● neurons, bipolar neurons (nasal epith)
● taste buds (live about 2 W) ○ only n to come in contact w external
envi
○ 1st order neurons of the olfactory
pathway
○ Basal stem cell → new olfactory
receptor
● Cells of the olfactory mucosa
○ olfact recptor
■ bipolar n w cilia/ olfact hair
○ supporting cells
○ basal cells
○ olfactory glands (Browmann)
○ receptor cells
○ basal cells
○ receptor cells
○ sensory afferent axon
○ microvilli that project into taste pore
● Taste cells synapse w primary sensory axons
Taste ● sweet, sour, salty, bitter, umami (glutamate) ● odorants bind to receptors
Transduct° ● ● Na+/ Ca2+/ Cl- channel open
● Depolarization occurs
salty/ sour sweet/ bitter/umami ● Nerve impulse is triggered
ion channel 2nd messenger
1. The odorant binds to a specific olfactory receptor
protein in the cell membrane of a cilium of an
olfactory receptor cell.
2. Receptor activation stimulates a heterotrimeric G
protein (Golf).
3. The α subunit of Golf activates adenylyl cyclase III
(ACIII) → cAMP.
4. The cAMP binds to a cyclic nucleotide – gated
● Each taste cell makes synaptic contact w a different (CNG) cation channel
1
, primary gustatory axon leads into CNS → gustatory 5. Opening of this channel increases permeability to
discrimination Na+, K+, and Ca2+.
● pathway 6. The net inward current leads to membrane
depolarization and increased [Ca2+]i
1. stimuls
7. The increased [Ca2+]i opens Ca2+ → activated
2. Cl− channels called anoctamin2 (ANO2) →more
n. taste bud depolarization (especially because of the relatively
high [Cl−]i of olfactory receptor neurons).
8. If the receptor potential exceeds the threshold, it
facial n (VII) ant triggers action potentials in the soma that travel
down the axon and into the brain.
glossophary n (IX) circumvallate + post ⅓
vagus n (X) epiglottis
3. solitary nc
4. medial lemniscus
5. Thalamus → insula
● Olfactory receptor axons terminate on the
dendrites of mitral cells (2nd order olfactory
neurons), in a restricted encapsulated strc
called glomerulus
○ 1 mitral cell → 1 odorant = primary
basis of olfactory coding
● Olfactory pathway :
○
2
The benefits of buying summaries with Stuvia:
Guaranteed quality through customer reviews
Stuvia customers have reviewed more than 700,000 summaries. This how you know that you are buying the best documents.
Quick and easy check-out
You can quickly pay through credit card or Stuvia-credit for the summaries. There is no membership needed.
Focus on what matters
Your fellow students write the study notes themselves, which is why the documents are always reliable and up-to-date. This ensures you quickly get to the core!
Frequently asked questions
What do I get when I buy this document?
You get a PDF, available immediately after your purchase. The purchased document is accessible anytime, anywhere and indefinitely through your profile.
Satisfaction guarantee: how does it work?
Our satisfaction guarantee ensures that you always find a study document that suits you well. You fill out a form, and our customer service team takes care of the rest.
Who am I buying these notes from?
Stuvia is a marketplace, so you are not buying this document from us, but from seller talootaloo12070503. Stuvia facilitates payment to the seller.
Will I be stuck with a subscription?
No, you only buy these notes for $5.49. You're not tied to anything after your purchase.