11/9 special senses Flashcards
what are the special senses?
they audition/vestibular; olfaction; vision; taste;
What are the basic components of sensory pathways?
receptors to detect changes/ stimuli in environment. mechanism to convert stimulus to electrical signal; transmit info to CNS
what does a Nociceptor sense?
extremes of pressure, temperature, noxious chemicals.
the process by which a stimulus activates a receptor and converts it into electrical energy.
sensory transduction. typically involves openging and closing of ion channels in receptor membrane
the basic path of sensory…
receptor creates a signal that is sent to first order neruons to the spinal cord, to second order neurons to the brain and thrid order to the cortex, and forth order in the cortex to interpret and integrate the signal
what will increase or decrease the likelihood that an action potential will actually be sent on a first order sensory neuron?
the receptor potential (these are graded potentials)
what is the level of sound pressure that would cause pain?
120dB. and damage is at greater than 100dB
what is the external ear?
the Pinna
what is the purpose of the middle ear?
to conduct the sound and impedance matching.
what is the inner ear purpose
to convert mech. to electrical
the small bones of the ears
ossicles
what is impedance matching?
it is how we overcome the loss of sound passing through the air: fluid interface. this is done by generating leverage to concentrate movements to more forceful vibrate the oval window.
the histology of the tympanic membrane
external, thin epidermis, inner simple cuboidal epithelium that sandwich a dense CT layer.
the histology of the middle ear
simple squamous epithelium that transistions into ciliatedpseudostratified epith. that sits on a thin LP that attaches to periosteum.
What is the eustachian tube?
the tube that connects the middle ear with nasopharnynx
What is the purpose of the eustachian tube
to equalize pressure between middle ear and environment and to drain mucus
what would repeated cases of otitis media cause (what type?)
conductive hearing loss due to inability to conduct sound through the middle ear, due to ossicle degredation.
otitus media
bacteria of nasopharnyx invade and multiply in the middle ear and you get a middle ear infection.
what is the result of otitus media repeated?
can cause hearing loss! and causes lots of expense and antibiotic use!
why fewer otitis media in adults?
adults have improved angle and size of the eustachian tube.
what can be done for lots of ear infection
ear tubes that will just fall out by themselves