The Role Of Receptors Flashcards
Why is the pacinian corpuscle specific?
It only responds to a single type of stimulus - mechanical pressure, not heat, light or sound
How does the pacinian corpuscle produce a generator potential?
It acts as a transducer
What is the role of the transducer?
It converts the information provided by the stimulus into a form that can be understood by the body, namely the nerve impulses
What is the role of receptors?
They convert, or transduce, one form of energy to another
What is the conversion of the energy of the stimulus into a nervous impulse known as?
A generator potential
Where are the pacinian corpuscles located?
Deep in the skin and in joints, ligaments and tendons
What does the sensory neurone ending at the centre of the pacinian corpuscle have in its plasma membrane, and what is this called?
A special type of sodium channel called a stretch-mediated sodium channel
What happens when pressure is applied to the pacinian corpuscle?
It changes shape and the membrane around its neurone becomes stretched which widens the sodium channels in the membrane and sodium ions diffuse into the neurone, thereby producing a generator potential
What does the generator potential produce?
An action potential that passes along the neurone and then, via other neurones, to the central nervous system
Where are the light receptor cells of the mammalian eye found?
The retina
What are the two types of light receptors?
Rods and cones
What do rod and cone cells act as?
Transducers that convert light energy into the electrical energy of a nerve impulse
What can rod cells not do, and what does this mean?
They cannot distinguish between different wavelengths of light so they can only produce black and white images
Which light receptors are most abundant within the eyes?
Rod cells
What does the pacinian corpuscle respond to?
Changes in mechanical pressure
What do many rod cells share?
A single sensory neurone
What does the fact that many rod cells share a single sensory neurone allow them to do?
Detect light of very low intensities
How does the fact that rod cells share a single sensory neurone allow them to respond to light of very low intensities?
A certain threshold value must be exceeded before a generator potential is created in the bipolar cells that they are attached to but as a number of rod cells are are attached to a single bipolar cell, there is a much greater chance that the threshold value will be exceeded than if only a single rod cell were attached to each bipolar cell
What must be done in order to create a generator potential?
The pigment - rhodopsin, in the rod cells, must be broken down
How does the idea of breaking down rhodopsin allow rod cells to respond to low light intensities?
Low light intensity is sufficient to cause this breakdown
What is low in rod cells?
Visual acuity
What are the differences in the distribution of the rod and cone cells in the eye?
The rod cells are distributed at the periphery of the retina whereas cone cells are more concentrated at the fovea
What pigment is found in cone cells?
Iodopsin
Why are cone cells less responsive to low light intensities?
A higher light intensity is required for the break down of Iodopsin and only a higher light intensity is therefore able to Crete a generator potential
What makes cone cells have high visual acuity?
Each cone cell has its own connection to a single bipolar cell which means the brain receives separate impulses that allow it to distinguish between two separate sources of light
