Week 12 - Special Sense Wrap Up Flashcards
(38 cards)
what type of epithelium is olfactory epithelium
(~5 cm²) yellow tinged patch of pseudostratified epithelium in the roof of the nasal cavity.
What does olfactory epithelium contain
o Olfactory sensory neurons (bipolar neurons). – bowling pin shaped receptor cells
o Olfactory cilia (non-motile, covered in mucus). – on apical dendrite of olfactory neurons
o Olfactory stem cells at the base – replaces damaged neurons.
*proteins binding to odorants keep them dissolved in mucus and transport them to dendrites
each olfactory neuron expresses how many receptor proteins
1
complex smells are detected through what
combinatorial activation. – pain and temperature receptors in nasal cavity – respond to irritants such as sharpness of ammonia, hotness of chilli and the chill of methanol
- also trigeminal nerve (CN V) also detects irritants (e.g., ammonia, menthol).
impulses from receptor proteins and olfactory neurons reach the CNS via what
afferent fibres of CN 5
What is the process of olfactory transduction
- odorant binds to receptor on cilia
- activate G-protein cascade
- depolarization
- action potential formation if threshold reached
what is the order of locations for the signals for olfactory transduction
- olfactory nerve fibers
- olfactory bulb
- synapse in glomeruli with mitral cells
do olfactory signals travel through the thalamus before reaching the cortex
no
what do olfactory senses have a strong connection to
limbic system (memory, emotion) and reticular formation (visceral reflexes like vomiting). – can trigger memories and vomiting
explain olfactory cross modal integration
- Certain brain areas (piriform cortex, amygdala) process smells with images or words (e.g., “banana”). -
- Odor responses depend on valence (personal like/dislike).
Odour modulated amygdala neurons change firing depending on personal preferences
Amygdala activation by odours with both positive and negative valence
what changes firing depending on valence (personal like/dislikes) for odor
amygdala
what is anosmia
- olfactory disorder
- loss of smell
- due to head trauma, inflammation, Parkinson’s,
- may be an early sign of Alzheimer’s disease
What is olfactory hallucinations
- olfactory disorders
- the experience of a particular (usually unpleasant) odour such as rotting meat often linked to temporal lobe epilepsy.
– involving the olfactory cortex and can occur as olfactory auras before the seizure begins or as olfactory hallucinations during the seizure
what are the 3 different types of taste buds
- fungiform papillae
- vallate papillae
- foliate papillae
what are fungiform papillae
- scattered across tongue
- (1–5 taste buds each),
- mushroom shaped
what are vallate papillae
- largest and least numerous,
- 8-12 make a V-shape at the back of the tongue (many taste buds).
what are foliate papillae
- located laterally on the tongue;
- active mainly in children and fewer with age
What are the 2 major cells in taste buds
- gustatory epithelial cells
- basal epithelial cells
what are gustatory epithelial cells
receptor cells with gustatory hairs.
* Receptor cell for taste (at least 3 kinds with different thresholds of activation)
* Long microvilli (gustatory hairs) projecting from tips and through taste pore – bathed by saliva on epithelial surface
* Gustatory hairs are the sensitive portion (receptor membrane)
* Sensory dendrites receive signals from several gustatory epithelial cells
What are basal epithelial cells
act as stem cells; replace gustatory cells every 7–10 days.
- Acts as stem cells as they divide and differentiate into new gustatory epithelial cells
- Replaced every 7-10 day because they are subject to friction and routinely burned by hot food
What are Type I Cells
- Gilia Cells
function: support and maintenance of the taste bud (support cells)
*Possibly involved in salt taste detection
What are Type II Cells
- Sweet
- Bitter
- Umami
Detects sweet, bitter and umami tastes
Receptor Cells
What are Type III Cells
- Sour
Detects sour taste
What are Type IV Cells
- Basal Cells
Function: Act as stem cells and divide and differentiate into the other types of cells (I, II, III)
