Role Of Receptors Flashcards
Receptors respond to changes and what are there 2 main features?
- specific to a single type of stimulus i.e. Mechanical pressure, heat, light
- produces a generator potential by acting as transducer: stimuli is in info we can’t understand transducers convert it into nerve impulses (generator potential)
What type of sodium channel does a Pacinian Corpuscle have?
Stretch-mediated sodium channel
In resting state what are the features of stretch-mediated sodium channels?
The membrane is too narrow to allow sodium ions to pass along them in this state Pacinian corpuscle has a resting state
What happens to Pacinian corpuscle when pressure is applied?
Changes shape and neurone becomes stretched
Stretch widens sodium channels so sodium ions diffuse into neurone
Influx causing depolarisation creating a generator potential and therefore action potential
Why do rod cells produce images only in black and white?
They cannot distinguish between different wavelengths of light
How can rod cells respond to very low light intensity?
Many share a single sensory neurone making it a greater chance that a threshold value will be exceeded in the bipolar cell to make a generator potential
What pigment do rod cells contain which has to be broken down in order for a generator potential to be reached?
Rhodopsin
What’s the consequence of many rod cells linking to a single bipolar cell?
Light recieved by rod cells sharing same neurone will only generate a single impulse. Meaning they cannot distinguish between seperate sources that stimulate them
Low visual acuity
Why do come cells only respond to high intensities of light?
Each have their own bipolar cell attaching it to a neurone this means the stimulation of many cone cells cannot be combined to help exceed threshold. So only high intensities can exceed threshold
What’s the pigment found in cone cells? And why does this re-enforce the fact come cells only respond to high intensities?
Iodopsin requires a high light intensity for its breakdown
Why can we not see colours in low light intensities?
As we use rod cells in this case and they cannot distinguish between wavelengths and only produce black and white images
Why do come cells have good visual acuity?
As each cells has its own connection to a bipolar cell, if two adjacent cones are stimulated the brain receives two separate impulses and can therefore distinguishe between the two seperate light sources
Why are cone cells found around the fovea?
Light is focused by the lens on this part of the retina which therefore receives high light intensities.
