Receptors Flashcards
Sensory reception function
responding to a different and specific type of stimulus
What do receptors act as
-transducer, producing generator potential
define generator potential
depolarisation of the membrane of receptor cell as the result of the stimulus
function of sensory perception
involves making sense of information from the receptors
function of pacinian corpuscle
transduces the mechanical energy of the stimulus into a generator potential
how does pacinian corpuscle produces a generator potential
by acting as a transducer
features of pacinian corpusle
-specific to a single type of stimulus > mechanical pressure only
-produces a generator potential by acting as a transducer
what does transducer do
convert change in form of energy by stimulus into nerve impulses
where do pacinian corpuscle occur
-deep skin
-most abundant on fingers, soles of feet and genitalia
-occur in joins like ligaments and tendons too
why is it important for pacinian corpuscle to occur in join
enable organisms to know which joints are changing directions
where is the single sensory neurone of a pacinian corpuscle
centre of layers of tissue , each separated by gel
what does the sensory neurone ending of pacinian corpuscle have
sodium channel in its plasma membrane (known as stretch-mediated sodium channel)
why are they called stretch-mediated sodium channel
their permeability to sodium changes when they’re deformed eg stretching
how pacinian corpuscle functions
-resting state = stretch mediated sodium channels pf membrane around neurone are too narrow to allow Na+ to pass along them > pacinian corpuscle has a resting potential
-pressure applied > PC is deformed and membrane around its neurone becomes stretched
-stretching widens the sodium channels in membrane and Na+ diffuses into neurone
-generator potential in turn creates an action potential (nerve impulse) that passes along neurone and then via other neurones to CNS
establishment of generator potential
-pressure applied > layers distorted > causing stretch-mediated Na channels to open > Na+ enter axon of sensory neurone
-generator potential established, excess Na+ insiden end of axon which causes depolarisation of membrane
-if enough generator potential are produced then an action potential will be established and a nerve impulse move along axon
where are light receptors on mammalian eye found
retina
two types of receptor cells found in eye and what do they both do
-rod cells
-clone cells
-both act as transducers by conserving light energy into electrical energy of a nerve impulse
what can’t rod cells distinguish
different wavelengths of light so images are only seen black and white
What are rods?
cells which cannot distinguish between the different wavelengths of light and processes images in black and white
what are many rod cells connected to
single sensory neurone in optic nerve
what are rod cells used to detect
light of very low intensity
why do rod cells respond to low-intensity light
-to create a generator potential the pigment (rhodopsin) must be broken down
-energy from low intensity light causes breakdown
Why can rods detect light at very low intensities?
-certain value has to be exceeded before generator potential
-created in bipolar cells to which rod cells are connected to a single bipolar cell retinal convergence
why is there a greater chance that threshold value will exceed than if only a single rod cell were connected to each bipolar cell
-summation
