Physiology of Taste and Smell Flashcards
What kind of receptor are those for taste and smell?
Chemoreceptors = stimulated by binding of particular chemicals
What does stimulation of taste and smell receptors induce?
Pleasurable or objectionable sensation
What do taste and smell provide a checkpoint for?
Quality control (ie has food gone off etc)
What do taste and smell influence in association with food intake?
Flow of digestive juices
What influences taste perception?
Information from smell receptors
What is gustation?
Term for sense of taste
Where are the sensory receptor cells of taste mainly packaged?
In taste buds
What are the sense organs of taste?
Taste buds
What do taste buds consist of?
Sensory receptor cells and support cells arranged like slices of orange
What is the life span of taste receptor cells?
About 10 days = replaced by basal cells within taste buds
What do taste receptor cells synapse with inside taste buds?
Afferent nerve fibres
Where are taste buds present?
Tongue, palate, epiglottis, pharynx
Where are the majority of taste buds found?
Sit in papillae in the tongue
What are the papillae of the tongue?
Finger-like structures which give rise to rough appearance of dorsum of tongue = seen in tongue as little red dots/raised bumps
How many types of papillae are in the human tongue?
4 types = filiform (most common, no taste buds), fungiform, vallate, foliate
What does the binding of taste-provoking chemicals (tastant) to receptors cells cause?
Alters cell ionic channels and produces depolarising receptor potential
What does the receptor potential created by the binding of taste-provoking chemicals cause?
Initiates action potentials in afferent nerve fibres which synapse with receptor cells
What conveys the signals from the tongue to the brain?
Cranial nerves = via brainstem and thalamus to cortical gustatory areas
What are some cranial nerves that carry afferent taste fibres to the brainstem?
7th = chorda tympani branch of facial nerve 9th = glossopharyngeal 10th = vagus
Where does the chorda tympani branch of the facial nerve innervate in relation to taste?
Anterior 2/3 of the tongue
Where does the glossopharyngeal nerve innervate in relation to taste?
Posterior 1/3 of tongue
Where does the vagus nerve innervate in relation to taste?
Areas in mouth other than tongue
What are the five primary tastes?
Salty, sour, sweet, bitter, umami
What causes a salty taste?
Stimulated by chemical salts, especially sodium chloride
