chemical senses Flashcards
chemoreceptors
monitor internal environment, chemical communication and integration
chemoreceptors are important for…
hunger, emotion, sex and memory
5 basic tastes
sweet sour salty bitter umami (savory)
T or F: aspartame is sweeter than sucrose
TRUE
what tastes bitter?
K+ (also salty), Mg2+, caffeine
apical end
sensory part of taste receptor cell
taste receptors cells synapse with..
gustatory afferent axons and basal cells
T or F: most cell respond to one taste
TRUE
saltiness mechanism
- Na+ enters through amiloride-sensitive Na+ channels
- open all the time, depolarizes taste cell
- anions affect the taste of salts
sourness mechanism
- lower pH (acid)
- H+ enters H+sensative TRP channl (PKD2L1), depolarizes cell
- selectively expressed in unique population of TRC’s
bitterness mechanism
- two families of receptor genes, T1R and T2R, these are G-protein coupled taste receptors
- 30 T2R genes used to recognize bitter
- PLC and taste cell specific cationic channel
sweetness mechanism
- many different tastants, ALL detected by the same receptor
- T1R2 + T1R3 (heteromeric dimers)
- activate same second messenger system as bitter
umami mechanism
- amino acids
- T1R1 + T1R3
- activate same second messenger as bitter
ageusia
no taste perception
central taste pathway
- cranial nerves VII (facial), IX (glossopharyngeal), and X (vagus) carry gustatory axons
- gustatory axons lead to medulla, thalamus, and cortex
- gustatory to VPM thalamus to primary gustatory cortex (brodmann’s 36)
- IPSILATERAL
T or F: each taste activates specific region of primary gustatory cortex
TRUE
vomeronasal organ
accessory to olfactory bulb to hypothalamus
mucus
complex mixture of antibodies, proteins, and odorant binding proteins which concentrate odorant
sensitivity of smell is determined by
size of olfactory epithelium and number of receptors
olfactory receptor neuron
- one dendrite
- unmyelinated axon
- form cranial nerve I (olfactory)
- fragile and easily damaged (anosmia)
olfactory signal transduction
- one mechanism
- bind to olfactory receptor on cilia
- stimulate G-protein
- activate adenylyl cyclase
- increase cAMP
- open cAMP-gated channels
- Ca2+ and Na+ enter cell
- Ca2+ activate, Cl- channels open
- depolarization
- AP fires if threshold reached
G-proteins are (#) transmembrane proteins
7
cAMP is the..
second messenger
where do olfactory receptor neurons synapse?
on glomeri in the olfactory bulbs
olfactory tracts connect…
to cortex BEFORE thalamus
olfactory connections to forebrain involve…
memory, motivation, and emotion
olfactory maps
spatial representations of odors
