Physiology Flashcards
Receptors for taste and smell are what kind? How are these stimulated?
Chemoreceptors- stimulated by binding to particular chemicals
What do taste and smell sensations influence in association with food intake?
The flow of digestive juices
Taste perception is influenced by what?
Information from smell receptors
The sensory receptor cells for taste are mainly packed in where?
Taste buds
What two cell types do taste buds consist of? How are these arranged?
Sensory receptor cells and support cells arranged consecutively
Taste receptor cells have a lifespan of how long? They are replaced from what?
10 days- replaced from basal cells within the taste buds
Where are taste buds mainly found?
Tongue, epiglottis, palate, pharynx
Taste receptor cells synapse with what?
Afferent nerve fibres
The majority of tastebuds sit on what structure of the tongue?
Papillae
What are the 4 types of tongue papillae? Which one does not contain taste buds?
Fungiform, vallate, foliate, filiform (does not contain)
When taste provoking chemicals bind to receptor cells, what happens to the membrane potential?
It depolarises
Afferent taste fibres reach the brainstem in the taste response via what 3 nerves and from where?
CNVII (chord tympani) from anterior 2/3rds of tongue, CNIX from posterior 1/3rd of tongue, CNX from epiglottis and pharynx
What chemicals trigger each of the different types of taste:
a) salty? b) sour? c) sweet? d) bitter? e) umani?
a) NaCl b) free H+ ions c) glucose d) alkaloids and poisonous substances e) amino acids (glutamate)
What do each of the following mean:
a) aguisia? b) hypoguisia? c) dysguisia?
a) loss of taste function b) reduced taste function c) distortion of taste function
What are some causes of aguisia?
Nerve damage, local inflammation, some endocrine conditions
What are some causes of hypoguisia?
Chemotherapy and medications
What 3 cell types are found in the olfactory mucosa?
Receptor cells, supporting cells, basal cells
Which cells in the olfactory mucosa secrete mucus?
Basal cells
What do odourants bind to?
Cilia which projects out from the olfactory mucosa
How long is the lifespan for olfactory receptors?
2 months
What do axons of olfactory receptors collectively form?
Afferent fibres of the olfactory nerve
Where do afferent fibres of the olfactory nerve pierce to reach the brain?
Cribiform plate of the ethmoid bone
How do odourants reach smell receptors during quiet breathing?
Diffusion
A substance must have what two properties in order to be smelled?
Sufficiently volatile and water soluble
What may be some causes of anosmia and hyposmia?
Viral infections, allergy, nasal polyps, head injury
What may hyposmia be an early sign of?
Parkinson’s disease
Give two examples of dysmosia?
Differently interpreting smells, hallucinations of smells
Lots of waves on a sound graph suggests what?
High frequency- high pitch
Few waves on a sound graph suggest what?
Low frequency- low pitch
High peaked waves on a sound graph suggest what?
High amplitude- loud
Low peaked waves on a sound graph suggest what?
Low amplitude- quiet
Which parts of the ear are: a) only associated with hearing? b) associated with hearing and balance?
a) Outer and middle, b) Inner
What is the function of the middle ear?
Amplify sound and pass vibrations via the oval window to the inner ear
What is the function of the Eustachian tube?
Ventilates the middle ear
What is the resting state of the Eustachian tube?
Closed
What muscles are responsible for opening the Eustachian tube?
Tensor veli palatini and levator palatini
When sound vibrations are passed through the oval window into the middle ear, what does this start?
Movement of the perilymph fluid
What is suspended within the perilymph?
Endolymph
What is the membranous labyrinth?
A series of sacs and ducts within the bony labyrinth
When sound waves are deflected towards the longest stereo cilia hairs in the middle ear, what does this cause?
Depolarisation
When sound waves are deflected away from the longest stereo cilia hairs in the middle ear, what does this cause?
Hyperpolarisation
Sound waves pass through the cochlea, maximally stimulating an area of where?
Basilar membrane
What is the function of the organ of corti within the basilar membrane of the cochlea?
Stimulates the cochlear nerve and central pathways - culminates activity in the superior temporal gyrus
What is sensory conflict, in terms of balance?
When visual input does not match proprioceptive input
What are the otolith organs?
Maculae of the utricle and saccule
In the vestibular area, what is fluid controlled by?
The movement of the head
What do semicircular canals detect and how?
Different directions of head movement based on the movement of the fluid inside them
Which parts of the inner ear are responsible for sending signals to the brain about the direction of head movements?
Hair cells of the utricle and saccule
