Receptors Flashcards

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1
Q

Sensory reception function

A

responding to a different and specific type of stimulus

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2
Q

What do receptors act as

A

-transducer, producing generator potential

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3
Q

define generator potential

A

depolarisation of the membrane of receptor cell as the result of the stimulus

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4
Q

function of sensory perception

A

involves making sense of information from the receptors

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5
Q

function of pacinian corpuscle

A

transduces the mechanical energy of the stimulus into a generator potential

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6
Q

how does pacinian corpuscle produces a generator potential

A

by acting as a transducer

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7
Q

features of pacinian corpusle

A

-specific to a single type of stimulus > mechanical pressure only
-produces a generator potential by acting as a transducer

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8
Q

what does transducer do

A

convert change in form of energy by stimulus into nerve impulses

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9
Q

where do pacinian corpuscle occur

A

-deep skin
-most abundant on fingers, soles of feet and genitalia
-occur in joins like ligaments and tendons too

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10
Q

why is it important for pacinian corpuscle to occur in join

A

enable organisms to know which joints are changing directions

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11
Q

where is the single sensory neurone of a pacinian corpuscle

A

centre of layers of tissue , each separated by gel

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12
Q

what does the sensory neurone ending of pacinian corpuscle have

A

sodium channel in its plasma membrane (known as stretch-mediated sodium channel)

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13
Q

why are they called stretch-mediated sodium channel

A

their permeability to sodium changes when they’re deformed eg stretching

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14
Q

how pacinian corpuscle functions

A

-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

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15
Q

establishment of generator potential

A

-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

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16
Q

where are light receptors on mammalian eye found

A

retina

17
Q

two types of receptor cells found in eye and what do they both do

A

-rod cells
-clone cells
-both act as transducers by conserving light energy into electrical energy of a nerve impulse

18
Q

what can’t rod cells distinguish

A

different wavelengths of light so images are only seen black and white

19
Q

What are rods?

A

cells which cannot distinguish between the different wavelengths of light and processes images in black and white

20
Q

what are many rod cells connected to

A

single sensory neurone in optic nerve

21
Q

what are rod cells used to detect

A

light of very low intensity

22
Q

why do rod cells respond to low-intensity light

A

-to create a generator potential the pigment (rhodopsin) must be broken down
-energy from low intensity light causes breakdown

23
Q

Why can rods detect light at very low intensities?

A

-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

24
Q

why is there a greater chance that threshold value will exceed than if only a single rod cell were connected to each bipolar cell

A

-summation

25
Q

consequence of many rod cells linking to single bipolar cell

A

-light received by rod cells sharing same neurone will only generate a single impulse travelling to brain regardless of how many neurones are stimulated
-so brain cannot distinguish between seperate sources of light that stimulated them
-so rod cells give low visual acuity
-so get low resolution to the image produced by brain

26
Q

how many cone cells are there

A

3 that respond to a different range of wavelengths of light
-depending on proportion of each type that is stimulated, we can perceive images in full colour

27
Q

how many cone cell is attached to
a bipolar cell

A

1

28
Q

problem of 1 cone cell being attached to a bipolar cell that is connected to a sensory neurone

A

-stimulation of a number of cone cells cannot be combined to help exceed threshold value and so create a generator potential
-so cone cells only respond to high light intensity

29
Q

what does it mean if cone cells contain different types of pigment (iodopsin)

A

-iodopsin requires a higher light intensity for its breakdown
-high intensity light will provide energy for break it down and create generator potential

30
Q

what does it mean if there are 3 different types of cone cells

A

-each contain specific iodopsin so each cone cell is sensitive to a different specific range of wavelengths

31
Q

what does it mean if 2 adjacent cone cells are stimulated

A

-brain receives 2 separate impulses
-so brain can distinguish between the two separate sources of light that stimulated the 2 cone cells
-giving accurate vision as they have good visual acuity

32
Q

what’s the distribution of rod and cone cells on retina like

A

uneven

33
Q

where are cone cells found and why

A

-fovea
-as they receive the highest intensity of light because light is focused by lens on part of retina opposite pupil
-conc of cone cells diminishes further away from fovea