Final: Sensory Systems: Ears Slides Flashcards
Other names for sensory cells
Receptor cells and modified neurons
Types of receptors (7)
Photoreceptors, mechanoreceptors, chemoreceptors, thermoreceptors, nociceptors, electroreceptors, magnetoreceptors
Function of sensory cells
Transduce physical or chemical stimuli into action potentials (convert signals into electrical activities)
Which types of receptors do humans have, and which do we lack?
Have: photo, mechano, chemo, thermo, nociceptors
Lack: electro, magneto
Photoreceptor function and location
Respond to light, found in eyes
Mechanoreceptor function and location
Convert their motion to electrical activity, found on skin and ears
Chemoreceptor function and location
Sense chemicals, can be internal (monitor pH/O2/CO2/etc. levels) or external (on tongue, nose, etc.)
Thermoreceptor function
Sense temperature
Nocicpetor function
Pain receptors
Electroreceptor function
Sense electrical fields (sharks have them)
Magnetoreceptor function
Sense magnetic fields (birds have them)
What is sound and how does it travel?
Vibration of air molecules; waves that dissipate as they travel
How can sound waves be characterized?
Amplitude (loudness) and frequency (pitch)
What organs does sound pass through as it’s transmitted (external to internal)?
Pinna, auditory canal, tympanic membrane, ossicles (malleus, incus, stapes), oval window, stimulation of hair cells in cochlea, auditory nerve, relay to temporal lobe of brain
Pinna (oracle) structure and function
Shaped like funnel; directs sound into ear
Parts of outer ear
Pinna and auditory canal
Parts of middle ear
Tympanic membrane (eardrum), malleus, incus, stapes
Parts of inner ear
Cochlea (where hearing occurs)
Function of ossicles
Amplifiers
Cochlea basic structure
Bone filled with fluid, hard tissue, connects to auditory nerve
Chambers of cochlea
Scala vestibuli, scala media/cochlear duct, scala tympani
Which cochlea chambers contain which fluid?
Scala media contains endolymph, scala vestibuli and scala tympani contain perilymph
What is the hearing apparatus and where is it located?
Organ of corti; located in scala media
Membranes in organ of corti
Tectorial membrane (on top) and basilar membrane (where hair cells sit)
Hair cell function
Mechanoreceptors that convert vibrational movement into electrical activity by forming synapses with sensory neurons (mechanical to electrical signal)
Kinocilium vs stereocilia
Kinocilium is tallest cilia, stereocilia are all the other cilia
Function of kinocilium
Point of direction when vibration occurs: depolarization when cell moves toward kinocilium, hyperpolarization when cell moves away from kinocilium
What triggers stretch gated channels to open?
Movement; they open when there’s vibration
Where are stretch gated channels located?
Between the cilia of hair cells
What kind of electrical activity do hair cells have?
Graded potential (or receptor potential)
What happens when hair cells are depolarized?
Cell moves towards kinocilium - stretch gated channels open - K+ ions enter - causes depol - activates voltage gated Ca chanels - triggers NT (glutamate) release - eventually cause action potential in afferent/sensory neuron
What neurotransmitter is involved in hair cell depolarization?
Glutamate
What happens when hair cells are hyperpolarized?
Cell moves away from kinocilium - stretch gated channels close - voltage gated calcium channels do NOT open - no NT release, no signal
Why does K+ enter instead of exit hair cells? (this is a SPECIAL CASE)
Endolymph fluid (surrounds hair cells) is rich in K+
What is the neural pathway of hearing?
Cochlear nerve fibers synapse on neurons in cochlear nuclei in medulla oblongata, signal sent to thalamus, information travels to auditory cortex of temporal lobe
What are some accessory structures in the ear and what do they do?
Oval window, round window, structures of outer and middle ear; they ensure that hair cells can send signals
