Terms in this set (50)
how many degrees of freedom does the vestibular system have?
x, y, and z linear planes
positive and negative
What types of detection do vestibular hair cells have?
What areas are important to the vestibular system
Ampullae of the semi circular canals
what senses angular movements?
cilia in the semicircular canals
What senses gravity
utricle and saccule hair cells
hair cells in either the saccule or utricle
hair cells in the ampullae of semicircular canals
what distinguishes hair cells in vestibular system from hair cells in auditory system?
cochlea does not have kinocilium
how is a kinocilium structurally different from the surrounding hair cells?
-a true stereocilium
-has 9+2 pattern
how are hair cells in the vestibular system connected to each other?
cupula: jelly like material over kinocilium and sterocilium
calcium carbonate crystals on top of cupula
allow maculae to sense movement because gravity has more of an effect on the crystals
what maculae detects up and down movement?
forward and backwards?
-up and down: saccule
-forward & back: utricle
-not exclusive though
how do the utricle and saccule differentiate up from down (or forward from backwards)
-arrows point toward kinocilium
-if you go down in an elevator, the otoliths will pull up, towards the kinocilium in top and away from kino cilium in the bottom half
-top depolarizes, bottom hyperpolarizes
line that separates differently oriented kinocilium in maculae
are otoliths required for all vestibular detections?
no, not in angular detection in semicircular canals
how do semicircular canals detect movement
turning causes circulation of fluid, which hyperpolarizes or depolarizes hair cells
how are kinocilium oriented in ampullae
point to front of head
describe how angular movement is detected
-turn head to left
-fluid moves to the right
-bends cupula to the right
-depolarizes hair cells on the left side of head
excessive amounts of endolymph in the membranous labyrinth
equilibrium is greatly disturbed
what system does Dr. Caprio think is most important?
eye movement and the vestibular system
-eye movement in infants is completely controlled by the vestibular system
-vestibular system much better at compensating based on 3D input
vestibular system and fish
-light from top & intact vestibular system: fish parallel to bottom of tank
-light from left & intact vestibular system: 45º
-light from left & no vestibular system: 90º
-50/50 light & vestibular control
how can some people not know they are hard of hearing
hearing loss can be tonotopic
occurs when transmission of sound waves to oval window is impaired
impacts all frequencies
helped by hearing aids
impaired transmission of nerve impulses
impacts some pitches more than others
results from damage to cochlea, hair cells, or auditory nerve
if primarily OHC destruction, helped by hearing aids
if IHC, need cochlear implant
can be caused by antibiotics
-direct electrical stimulation of nerve
-microphone on outside picks up sound
-Fourier analysis deciphers it and sends electrical signal to area that frequency represents
how many electrodes are needed for a cochlear implant
why is earlier better in terms of cochlear implants
best in first 3.5 years of life
when central auditory pathways show most plasticity
what nerve do cochlear implants stimulate
what is a negative of cochlear implantation
destroys supporting cells
supporting cells could possibly, in the future, be used to produce HC's
comparative physiology of hair cell renewal
human hair cells don't regenerate following loss or damage
lateral lines of fish & aquatic stage amphibians can regenerate
sharks get more hair cells as the age
birds might be able to regenerate HCs
hair cell regeneration
-hair cells suppress support cells from entering cell cycle
-destruction of hair cells relieves inhibition & triggers transdifferentiation & proliferation
transdifferentiation vs proliferation
proliferation: enters cell cycle, produces 2 daughter cells, can become either support cell or hair cell
transdifferentiation: support cell becomes HC
types of genetic deafness
syndropic:causes deafness & some other dysfunction
non-syndropic: only affects the ear
most common defect in genetic deafness
DFN1: affects supporting cells in inner ear, 40% of genetic deafness
How is deafness acquired?
death of HCs
death of spiral ganglion neurons
can be due to overexposure to loud sounds, bacterial or viral infections, or ototoxic drugs
how do defective support cells cause deafness?
decreases tension in membrane & reduces sensitivity of HCs
what does otoferin do?
what does the spiral ganglion neuron do?
transmits sound from cochlea to brain
cells taken from newborn mouse ears were able to switch off p27 gene, those that did could divide & produce new hair cells
only switched off in 2% of 2-week olds, so gene is firmly switched on with age
Math1 (AToh1) gene
in mature guinea pigs, Math1 is necessary and sufficient to direct hair cell differentiation
is a transcription factor & positive regulator of hair cell differentiation
'functional repair of organ of corti in mature deaf mammals'
Atoh1 in utero gene transfer
if a woman took an ototoxic drug while pregnant, in utero gene transfer could produce more hair cell that are fully functional
a basic helix-loop-helix transcription factor
problems with Atoh1 gene therapy
-can't fix hearing loss caused by genetic mutation-> would produce more defective HCs
-need to find a way to regulate it: uncontrolled differentiation results in cancer
HC regeneration and Notch signaling
notch receptor suppresses HC differentiation, so inhibiting Notch signaling could produce new HCs
other cell cycle inhibitors that could be inhibited to generate HCs
supporting cell damage response
when HCs die, SCs maintain the epithelial barrier integrity, ensuring fluid compartments remain separate
apical expansion of SCs
go over slide 39 again
YOU MIGHT ALSO LIKE...
Core Topic 1 Cell Biology | IB Biology Guide
CELS 191 - Lecture 33 - Cloning, Stem Cells and Gene Therapy
Integrated Bio- Exam 1
Stem Cells Final Exam
OTHER SETS BY THIS CREATOR
Lecture 14: Microtubules
Lecture 9: ER translocation
Lecture 19: Biosynthesis of Membrane Lipids
Lecture 8: Post-translational Targeting of Proteins
THIS SET IS OFTEN IN FOLDERS WITH...