Final material: sensory transduction II and III

What types of cells are in the olfactory epithelium?

Olfactory sensory neuron, supporting cell, basal cell.

The axons of olfactory sensory neurons pass through which bony structure to reach the olfactory bulb?

Cribriform plate

What clinical term describes states in which the sense of smell is dramatically enhanced?

Hyperosmic states.

Olfactory axons penetrate the cribriform plate through small holes called _____.

Foramina

Where are the regions of odorant sensitivity?

Cilia, distal dendrite

Describe the general pathway of olfactory transduction.

Odorant binds to receptor—>Golf is activated—>adenyl cyclase is activated—>cAMP produced—>Ca2+ and Na2+ enter and depolarize the cell—>Cl- efflux—>phosphodiesterase breaks down cAMP to terminate the signal.

Do filiform papillae have taste receptors?

No

Where are fungiform papillae primarily located on the tongue?

Anterior 2/3rds of the tongue

Which papillae line the sides and the posterior region of the tongue?

Foliate papillae.

Where are circumvallate papillae found?

At the back of the tongue.

In which cellular region of a taste receptor cell does signal transduction occur?

Apical region

Function of basolateral region of taste receptor cells

general cellular housekeeping and synaptic transmission

What channel is involved in the salt taste transduction system?

amiloride-sensitive Na+ channel

What ion current enters sour receptor cells to cause depolarization?

H+

The sweet taste transduction works through what G protein?

Gustducin

What is the molecular structure of the primary sweet taste receptors?

T1R2-T1R3 heterodimeric GPCRs.

How does quinine act ionotropically on taste cells?

By directly blocking K+ channels.

Most bitter taste receptors belong to which GPCR family?

T2R

Name 2 umami receptors:

T1R1-T1R3 heterodimeric GPCRs

metabotropic glutamate receptors like mGluR1 and mGluR4

What is the 'paradoxical cold' sensation?

The activation of cold receptors in the skin by high (burning) temperatures.

What is the molecular name of the receptor that is sensitive to both cold and menthol?

CMR1

Which heat-sensitive TRP channel also binds to capsaicin?

VR1 (Trpv1).

What is the hypothesized molecular basis for the 'burning cold' sensation?

Nociceptive neurons containing both Trpv1 (heat) and TRPA1 (extreme cold) channels.

Snakes like rattlesnakes use which organ to detect infrared radiation?

The pit-organ.

Other than snakes, what animals have IR sensors?

Vampire bats, melanophila beetles

Structurally, what type of nerve endings are nociceptors?

Free nerve endings

Aδ fibers are _________(myelinated/unmyelinated) nociceptors, while C fibers are __________(myelinated/unmyelinated).

Myelinated; unmyelinated

Which nociceptor fiber type mediates sharp, prickling, and well-localized pain?

Aδ fibers

Which nociceptor fiber type mediates dull, aching, and diffuse pain?

C fibers.

What are the 2 subcategories of Aδ fibers?

high threshold mechanical (HTM), and mechanothermal

Polymodal nociceptors (PMNs) respond to which three types of stimuli?

Intense mechanical, thermal, and chemical irritants

What chemicals do polymodal nociceptors respond to?

Histamine, bradykinin, prostaglandin E2 (PGE2), leukotriene C4

Define 'allodynia'.

Pain produced by a non-noxious stimulus, such as light touch.

Which three chemicals are injected into the skin by the 'stinging nettle' plant?

Histamine, acetylcholine, and 5-HT (serotonin).

Gympietide toxins specifically block the inactivation of which ion channel?

Nav1.7 channels.