Which cells, found in the inner ear, convert sound energy (moving them) into action potentials?
Hair cells (stereocilia)
Hair cells are connected to ___ ___ neurons.
What excites stereocilia?
Movement by sound energy
Which channels are found at the tips of stereocilia?
What enters when they are open?
K+ (which ENTERS unusually and depolarises the membrane)
When stereocilia are excited by movement and the opening of tip link channels, the sensory neurons connected to them are EXCITED.
Which neurotransmitter is released to cause an excitatory action potential?
Hair cells are found throughout the labyrinth of the inner ear, which is responsible for hearing and balance.
The function of hair cells changes based on their ___ in the labyrinth.
What properties of a sound wave match to
Why do vibrations received by the tympanic membrane need to be amplified before they pass into the cochlea?
It takes more energy to vibrate fluid compared to air
Which bones are mostly responsible for amplifying the vibrations received by the tympanic membrane?
Which chamber in the Organ of Corti contains the hair cells?
Which membrane do hair cells sit on in the Organ of Corti?
What properties of the basilar membrane allow to discriminate between sounds of different pitches?
Oval window end (the base) is wide and flexible
Apex is narrow and stiff
So different energy levels i.e pitches of sound are required to move the hair cells depending on what end you're at
Which membranes are found
a) superior to
b) inferior to
hair cells in the Organ of Corti?
a) Tectorial / Reissner's membrane
b) Basilar membrane
The basilar membrane changes the ___ of hair cells by bending in response to sound energy.
The tectorial membrane actively ___ hair cells by vibrating.
basilar membrane changes hair cell position
tectorial membrane moves hair cells by vibrating
The potassium concentration of the fluid surrounding hair cells (?endolymph) is (high / low).
high K+ concentration
In which direction does potassium move when the tip links of hair cells are open?
K+ concentration in endolymph is high
Which fluid is found in the scala media?
Which fluid is found in the scala vestibuli and scala tympani?
What happens to the potassium which enters hair cells through tip links?
After action potential K+ is recycled back into scala media to keep conc. gradient the same
How are hair cells arranged in the Organ of Corti?
Which layer of hair cells is concerned primarily with sensory input?
Which nerve carries the sensory neurons from the inner hair cells?
Cochlear part of CN VIII
Each inner hair cell is supplied by (a single / many) sensory neuron(s).
each inner hair cell has its own sensory neuron
What is the primary function of outer hair cells?
Movement of the tectorial membrane to enhance vibration
How many outer hair cells are connected to each somatic efferent fibre?
Where do sensory neurons synapse between the inner hair cells and CN VIII?
superior olivary ganglion somatic efferents outer hair cells
sensory coding of pitch depends on firing rate of hair cells AND where they are on the basilar strip
On which side of the brain are auditory signals processed?
processing is bilateral
Briefly describe how auditory stimuli reach the primary auditory cortex from the inner ear.
CN VIII fibres > Spiral ganglion > Cochlear nucleus > Superior olivary nucleus > Inferior colliculus > Medial geniculate nucleus > Primary auditory cortex