Sensory Physiology and Pain Flashcards
(63 cards)
what do extero-receptors detect?
- vision
- hearing
- taste
- smell
- receptors on skin: physical change temperature or pain
what do intero-receptors detect?
information from internal organs and processes
proprioception helps to detect what?
position and load
what is adequate stimulus?
the least amount of energy in a stimulus needed to generate a receptor potential to form an action potential downstream
what is the adequate stimulus for vision?
light
what happens when light is received by cells within the retina?
cGMP gated sodium channels CLOSE causing hyperpolarization
- retinal in rhodopsin undergoes a conformational change to activate the G protein transducin which activates posphodiesterase to catabolize cGMP
what happens when darkness is received by cells within the retina?
cGMP gated sodium channels are OPEN causing depolarization
how are ON center bipolar cells activated?
ON center bipolar cells have metabotropic glutamate receptors that are inhibited by glutamate, so they are activated when light is present
how are OFF center bipolar cells activated?
OFF center bipolar cells have ionotropic glutamate receptors that are excited by glutamate, so in the dark they are active
what is the role of horizontal cells and lateral Inhibition of the retina?
horizontal cells receive input from photoreceptors and inhibit neighboring bipolar cells through inhibitory interneurons, sharpening contrast through lateral inhibition
*only effects the surrounding cells
structure and function of the external ear
air filled with pinna andexternal auditory canal
- function is to funnel sound waves into the middle ear
structure and function of the middle ear
air filled with a tympanic membrane, malleus, incus and stapes
- function is to transmit signal from tympanic membrane to oval window
structure and function of the inner ear
fluid filled with semicircular canals and a cochlea (scala vestibuli, scala tympani, and scale media) that contains the organ of corti
what is impedance matching?
process by which sound waves from the air filled middle ear are efficiently transferred to the fluid-filled cochlea in the inner ear
*without this you would have hearing loss
what do the scala vestibuli,
scala tympani, and scale media contain?
- scala vestibuli and scala tympani contain perilymph (low K+)
- scale media contains endolymph (high K+)
what is the adequate stimulus for hearing?
sound waves
what happens when a sound wave strikes the tympanic membrane?
vibration of ossicles vibrates the oval window then the organ of corti induces cilia to bend and OPEN mechanical sensitive K+ channels causing influx of K+ from endolymph into the hair cell which releases glutamate
what is the adequate stimulus for vestibular balance?
head movement
what are the structures included in the vestibular system?
3 perpendicular semicircular canals with ampulla and two otolith organs (utricle and saccule) that are also filled with endolymph
what is stimulated when you move your head counterclockwise?
stimulates left horizontal canal hair cells to
bend towards the kinocilium and inhibits right horizontal canal.
nystagmus is the result of
vestibulo-ocular reflex
what are the two components of nystagmus and which one is it defined by
- Slow Component: the eyes move opposite to the direction of the head spin to maintain visual stability
- Fast Component: once the eyes reach their movement limit, they rapidly snap back in the same direction as the head movement.
*defined by the fast
what is vertigo and what induces it?
inappropriate sense of motion can be induced by:
- low blood pressure
- infections
- anesthesia
- certain drugs (loop diuretics, erythromycin, nitrous oxide, chemotherapy)
- temperature
- displaced otoconia
- tumors
- visual clues
what drugs can be used for treatment of vertigo or motion sickness?
Anti-histamines
* Meclizine (Bonine®, Antivert®)
* Dimenhydrinate (Dramamine®)
* Promethazine (Phenergan®)
* Diphenhydramine (Benadryl®)
Parasympatholytics
* Scopolamine (Transderm-Scop®)