Smelling smell Flashcards
1st step: in smell?
volatile compound inhaled
2nd step: in smell?
compounds make their way to olfactory epithelium and gets trapped in mucus.
3rd step: after getting trapped in mucus..
Odourant receptors GPCR on cilia of olfactory receptor neutron cells sense and respond to the chemical signal via shape change.
4th step: After compound shape is recognised…
Odourant receptor GPCR undergoes and confirmational change, resulting in a change in the g-proteins which initiates signal transduction cascade.
5th step: transduction cascade results in?
nerve impulses being sent to olfactory bulb and then to other parts of parts of the brain where smell is perceived.
how many odourant receptors do we have?
Over 400 that all have slightly different binding pockets, hence different odourant binding profiles.
Changes in GPCR proteins results in?
separation of olfactory G protein (Golf)
Part of the olfactory G protein goes on to active..
Adenylate cyclase (AC)
AC produces secondary messenger…
cAMP
increase levels of cAMP open…
ion channels and increase concentration of Ca2+ and Na+
Increased levels of Ca2+ and Na+ results in…
sending of electrical potential across the olfactory receptor nerve fibres (axons) to olfactory bulb in the brain.
Signals from olfactory bulb get sent to…
several regions of the brain, including regions of emotion, memory and smell perception.
Pattern recognition, different combination of receptors helps distinguish more odours.
How many combinations can we recognise?
over 1000
The olfactory system does not interpret single smell compounds but…
the whole odourous mix
define olfactory fatigue?
temporary inability to distinguish a particular odour after prolonged exposure.
