Physiology Flashcards
What kind of receptors are the receptors for taste and smell?
Chemoreceptors
Which 2 types of cells do taste buds consist of?
Support cells
Sensory receptor cells
(these are rearranged like the slices of an orange)
Which of the following papillae does not contain taste buds?
- foliate, valate, filiform, fungiform
Filliform
How often are taste receptor cells replaced?
Every 10 days
Name the 5 primary tastes
Salty Sweet Sour Bitter Umami
Salty taste
Stimulated by chemical salts, especially NaCl
Sweet taste
Stimulated by configuration of glucose
Sour taste
Stimulated by acids which contain free H+ ions
Bitter taste
Stimulated by diverse group of tastiest
Umami taste (meaty or savoury)
Triggered by amino acids (esp glutamate)
Ageusia
Loss of taste function
Hypogeusia
Reduced taste function
Dysgeusia
Distortion of taste function
Cell types present in the olfactory mucosa (3)
Olfactory receptor cells
Supporting cells
Basal cells
Basal cells function
Act as precursors for new olfactory receptor cells
2 main requirements for a substance to be smelled
Volatile
- some of its molecules can enter the nose with inspired air
Water soluble
- can dissolve in the mucous coating of olfactory mucosa
Anosmia
Inability to smell
Hyposmia
Reduced ability to smell
Dysosmia
Altered sense of smell
what is sound?
Pressure wave caused by oscillating molecules
Function of external ear
Sound collector
Receives sound and funnels it into ear drum
What are the components of the ossicular chain
Malleus
Incue
Stapes
- connected to each other by synovial joints
What does the stapes connect on to?
Oval window
What happens when pressure waves cause the stapes to vibrate against the oval window?
Vibrations travel up the perilymph (fluid) in the cochlea.
Different thicknesses of basilar membrane vibrate in response to different frequencies of sound
Which structure of the inner ear contains receptors for transduction?
Cochlea
What is transduction?
Conversion of a mechanical wave into an electrical signal
What is the basilar membrane and where is it located?
Mechanical analyser that runs the length of the cochlea, curling towards the cochlea’s centre.
It vibrates in different regions depending on the frequency of the sound waves impinging on it
Where do sound waves exit?
Through the round window
Where is the site of sound transduction?
Organ of corti
What does the organ of corti contain on its surface?
Lots of stereo cilia (which are mechanoreceptors)
What happens when stereo cilia hair cells are bent by vibrations?
The hair cell membrane is depolarised and an electrical signal (action potential) is transferred to the cochlear nerve.
High frequency sounds vibrate the basilar membrane near the start/near the end
Near the start (near the oval window)
Low frequency sounds vibrate the basilar membrane near the start/near the end
Near the ned (travel further along the membrane towards the inner turns)
What is the normal range of sound frequency for humans to perceive?
20Hz - 20,000 Hz
Balance: what are the 5 vestibular receptor organs in the inner ear that make up the vestibular labyrinth?
Utricle
Saccule
3x semicircular canals
Balance: what do stereo cilia project into?
Gelatin (which contains calcium carbonate crystals - otoconia).
Balance: what happens to the stereo cilia and gelatine when the head is tilted?
Crystals continue to be pulled straight down by gravity.
The new angle causes the gelatin to shift, thereby bending the cilia
Balance: what happens when there is bending of stereo cilia
Stimulation of specific neurones that signal to the brain that the head is tilted, allowing maintenance of balance
Balance: semicircular canals function
Detects angular acceleration or decelleration
Balance: what happens to the fluid in the semi-circular canals when the head turns?
The fluid in the canals shifts which bends the stereo cilia and sends signals to the brain
Balance: the otolith of the utricle and saccule
Viscous gel that contains calcium carbonate crystals
Balance: What happens to the otolith when the head is tilted
Moving of the otolith bends the stereo cilia which causes some hair cells to depolarise and others to hyperpolarise
Balance: what does the ampulla of the semicircular canals contain?
Hair cells that respond to rational movement
e.g. when turning head from side to side to signal “no”
Balance: where in the semicircular canal is the cupula found?
Attaches to the top of the ampulla
Balance: What happens to the cupula as the head rotates?
As the head rotates, the cupula bends in the opposite direction of the rotation
What is the vestibule-ocular reflex (VOR)
Preserving image on the centre of visual field during head movement by producing eye movement in the opposite direction of head movement
(e.g. when head moves to the right, the eyes move to the left)
