25 Questions
What type of papillae on the tongue does not have taste buds?
Filiform papillae
Which type of papillae is located at the junction between the posterior ⅓ and anterior ⅔ of the tongue?
Circumvallate papillae
What is the role of Von Ebner glands in the tongue?
They secrete saliva that helps to dissolve taste molecules
What is the function of the synapse between receptor cells and nerve fibers in taste buds?
To transmit the taste sensation to the brain
How many nerves are involved in transmitting taste information from the tongue to the brain?
3 nerves
Which structure is involved in conscious perception of olfaction?
Dorsomedial thalamic nucleus
Which of the following is NOT directly related to emotion?
Piriform cortex
What is the role of the hypothalamus in the olfactory system?
Generating autonomic responses
How many main tastes are recognized?
5
Which structure is involved in the emotional performance of olfaction?
Amygdaloid nucleus
What is the primary function of the ventral-posterior nucleus of the thalamus in the context of taste processing?
Relay station for taste inputs from the Solitary tract nucleus
Which nerve is responsible for conveying somatosensory sensations from the anterior ⅔ of the tongue?
Lingual nerve, branch of the V CN
What is the primary role of the orbitofrontal cortex in the context of flavour perception?
Integrating visual, taste, and somatosensory inputs
Where are the cell bodies of the glossopharyngeal nerve (IX CN) located?
Petrosal ganglion
What is the primary contributor to the sensation of flavour in food?
Olfaction from volatile molecules
What is the primary function of the somatosensory system in relation to food perception?
To provide texture and thermal sensations
What is the term for a disorder where one perceives a sweet taste as sour?
Dysgeusia
What is the purpose of using non-irritating substances in olfactory examinations?
To prevent somatosensory inputs
What is the term for the complete loss of smell?
Anosmia
What is the primary goal of the electrogustometry examination?
To map the regions of the tongue corresponding to specific tastes
What is the primary mechanism of transduction for sour taste?
Blockage of potassium channels by protons
What is the function of glutamate receptors in taste perception?
Detection of umami taste
What is the characteristic of receptors involved in sweet taste transduction?
G protein associated receptors
What is the common characteristic of salty and sour taste transduction mechanisms?
Involvement of ionic channels
Where are the receptors responsible for taste perception located?
In specific receptor cells
Study Notes
Taste and Flavour
- The tongue has three nerves and three ganglia, but a single nucleus (destination) for taste information
- Anterior ⅔ of the tongue is responsible for taste and touch, conveyed by the chorda tympani (branch of VII CN) and lingual nerve (branch of V)
- Posterior ⅓ of the tongue is responsible for taste, conveyed by the glossopharyngeal nerve (IX CN)
- Oropharynx is responsible for visceral information, conveyed by the vagus and X CN through the superior laryngeal nerve
Taste and Flavour Integration
- Taste inputs travel to the cortex, relaying through the thalamus, specifically the ventral-posterior nucleus (VPM)
- From the thalamus, taste inputs reach the insula and then the orbitofrontal cortex, where integration with other sensory inputs occurs
- Flavour includes taste, olfaction, and somatosensory inputs
- The orbitofrontal cortex receives visual, taste, somatosensory, and other inputs, and integrates them to form flavour
Olfaction
- Olfaction is responsible for most of the flavour we interpret from food
- When we have a cold, food tastes different due to reduced olfaction
- The olfactory system contacts the hypothalamus to generate autonomic responses
- The olfactory system also connects with the hippocampus, amygdaloid nucleus, and piriform cortex, influencing emotions, memory, and behaviour
Taste
- There are 5 recognized tastes: sweet, salty, sour, bitter, and umami
- The taste bud includes receptors, expressed on gustatory cells, and supporting cells
- Receptors make synapse with gustatory fibres, carrying taste sensation to the brain
- Taste buds are grouped in papillae on the tongue, but scattered in other parts of the oral cavity
Types of Papillae
- Filiform papillae have no taste buds
- Fungiform papillae have taste buds on the lateral wall
- Circumvallate papillae are located at the junction between the posterior ⅓ and anterior ⅔ of the tongue
- Foliate papillae have taste buds and Von Ebner glands, which secrete saliva
Disorders of Olfaction and Taste
- Ageusia: no taste
- Hypogeusia: reduction of taste
- Dysgeusia: misinterpretation of taste
- Anosmia: no olfaction
- Hyposmia: reduction of olfaction
- Parosmia: no correct interpretation of smells
- Cacosmia: a type of parosmia, where everything smells bad
Examination of Taste and Olfaction
- Taste tests: examining main tastes by applying substances to specific regions of the tongue
- Electrogustometry: a test to examine taste
- Olfaction tests: using non-irritating substances to examine olfaction, with each nostril explored separately
Learn about the structure and function of taste buds, including the role of receptors, gustatory cells, and papillae on the tongue and other parts of the oral cavity. Discover how taste buds transmit sensory information to the brain.
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