Taste buds and stuf Flashcards
What part of the tongue has specialized mucosa?
Dorsal
Body of the tongue
Anterior 2/3
Root of the tongue
Posterior 1/3
Terminal sulcus
Divides the anterior and posterior portions of the tongue
What type of epithelium covers the tongue
Mostly keratinized
What give the tongue its rough surface?
Papillae
What CN inneervate the taste buds?
VII, IX, X
What provides touch sensory to the tongue?
A-beta fibers
What innervates warming sensation of the tongue
C-fibers
What innervates cooling sensation of the tongue?
A-delta fibers
What provides pain sensation of the tongue
A-delta and C-fibers
What provides somatosensory innervations of the anterior tongue?
CN V
What provides somatosensory innervation to the posterior of the tongue
CN IX
Meissner Corpuscles
Large (A-beta) axons that terminate in the superficial lamina propria between rete pegs
Which nerves are “rapidly adapting”? what does that mean?
Meissner Corpuscles
Respond only to the changing aspects of the stimulus - mechanically sensitive receptors are embedded in the nerve fiber endings
Which nerves are “slowly adapting”? What does that mean?
Merkel endings
Respond both to the changing aspects and static phases of stimulus
In Merkel endings, where does the initial firing come form, and where does the continued firing come form?
Initial firing comes from activation of the receptors in the nerve fiber itself
Sustained firing comes from activation of receptors in the Merkel cell which communicates synaptically with the associated fiber
Nocioceptors
Free nerve endings that sense pain
Merkel endings and Meissner corpuscles can’t code for nosxious sensations
What are some things taste can detect/distinguish?
Can distinguish nutritive v non-nutritive substances
Can distinguish nutrients
Can detect harmful substances
What are the 5 classes of taste reception?
Sugars - sweet Amino acids - umami Salts - salty Acids - sour Varied - bitter
T/F - Sensations of spiciness is dependent of taste system
False - dependent on the pain system - TRP receptors
How many cells in a taste bud? How are these cells oriented
40-60
90 degrees to the rest of the epithelium
What cellular structure are taste receptors located?
Microvilli
Taste pore
Opening to keratinized layer to let things diffuse and be sensed by microvilli
Lateral to the microvilli
T/F - Taste buds are only on the tongue
False - they are mostly on the tongue, but there are some in the pharynx and soft palate
Fungiform papillae shape
Mushroom shaped
What innervates fungiform papillae?
Chorda tympani branch of VII
-They arise from arch I, but the innervation arises from arch II
Where are fungiform papillae located?
On the dorsal anterior tongue, among more numerous filliform papillae
Filiform papillae
Spine shaped
Heavily keratinized
Do not contain taste buds
Innervated by sommatosensory only
Foliate papillae location. Why is it strategic?
Lateral aspect of the posterior portion of the anterior tongue
Monitor food during chewing
Where are taste buds located of foliate papillae?
In the trenches
Where are taste buds of fungiform papillae located?
On the top
Foliate papillae
2-9 parallel folds in dorsoventral orientation
Closely associated with Von Ebners glands
Circumvallate papilae
8-10 papillae arranged in a V in the most posterior anterior tongue
What is the structure of circumvallate papillae?
Central connective tissue core surrounded by a trench
Why is the location of circumvallate papillae strategic?
Monitor food just before swallowing
Where are tastebuds located in Circumvallate papillae?
In the trench
What happens when a single taste nerve is damaged?
The effects of that single taste nerve an be clearly detected. However, when that person is allowed to use all the taste buds in their mouth, the effects are very minor
Type I cells
Stain for glial markers and don’t have microglia or synapses.
This suggests that these cells are likely for support
Dark staining taste bud cells
Type I cells
Light staining taste bud cells
Type II cells
Type III cells
Type III cells
Sour
Synapse with primary afferent nerve
Have microvilli
Type II cells
Bitter, sweet, amino acids
Do not synapse with primary afferent nerve
Have microvilli
How do type II cells get their messages to the brain?
ATP is released from type II cells without the aid of a typical synapse, and uses a special voltage-gated ion channel
What signaling molecule do precursor taste buds cells express?
Shh
How do taste buds develop?
First develops as a specialization of epithlium called a ‘placode’
Development requires cell-to-cell signaling
Final differentiation requires neural innervation
When does the tongue appear?
Week 4 IU
When do the lingual papillae develop?
Week 8 IU
When do taste buds first appear?
Week 8 IU
When do taste pores appear?
Week 12 IU
