The olfactory system Flashcards
What receptor type is involved in olfaction?
GPCRs
- Many different receptors but all are coupled with the G protein Golf
Where do the olfactory projections go?
- Hypothalamus (sex and neuroendocrine)
- Reticular formation (visceral responses)
- Amygdala (emotional responses)
- Hippocampus (olfactory memory)
- Olfactory cortex (concious smell)
What are glomeruli?
- Little areas of the olfactory bulb which are associated with a certain type of receptor
- One on each side of the hear
- Each specific receptor TYPE sends projections to the glomeuli on either side of the head
What is the structure of the olfactory epithelium?
Mucus layer
- Bathes cilia of olfactory receptor cells
Supporting cells and olfactory receptor cells
- Supporting cells secrete the mucus
Basal cells
- Produce new olfactory receptor cells (one of the only neurons to be replaced)
What are the features of the olfactory receptor cells?
- Receptor cells are both the sensory receptor and the primary afferent neuron
- Thin and unmyelinated
- Project through the cribiform plate and into the olfactory bulb (in the forebrain)
- Form the olfactory nerve
What happens in the mucus layer of the olfactory epithelium?
- Odorant molecules dissolve in the mucus
- Cilia which bathe in the mucus is where the transduction machinery is
What is the olfactory epithelium?
- Small, thin sheet of cells
- High up in the nasal cavity
- Used to smell (NOT THE NOSE)
What do the cilia in the olfactory epithelium have high levels of Cl-?
So when ANO2 channels are open, Cl- moves OUT, increasing the depolarisation of the membrane
What is the olfactory pathway?
- Activate GPCR which activates adenylyl cyclase
- ATP –> cAMP
- Opens a cyclic nucleotide gated channel (CNG)
- Na+ and Ca2+ into the cell
- Opens ANO2 (Cl- channel)
- Cl- OUT of the cell
- Causes further depolarisation which spreads fro the cilia into the main dendritic portion
- Action potential if above thereshold
