Receptors Flashcards
What is a pacinian corpuscle specific to
A single type of stimulus, in this case it responds only to mechanical pressure. It will not respond to other stimuli such as heat light or sound
What does a pacinian corpuscle produce
A generator potential by acting as a transducer
What’s the role of the transducer in the pacinian corpuscle
Convert the change in form of energy by the stimulus into a form, namely nerve impulses, that can be understood by the body
Receptors in the nervous system convert the energy of the stimulus into a nervous impulse; what’s this known as
Generator potential
What do pacinian corpuscle respond to
Mechanical stimuli
How does the pacinian corpuscle function with a stretch mediated sodium channel
The stretch mediated sodium channels of the membrane around the neurone of a pacinian corpuscle are too narrow to allow sodium ions to pass along them. The neurone of the pacinian corpuscle has a resting potential
When pressure is applied to the pacinian corpuscle, it is deformed and the membrane around its neurone becomes stretched
This stretching widens the sodium channels in the membrane and sodium ions diffuse into the neurone
The influx of sodium ions changes the potential of the membrane (becomes depolarised) thereby producing a generator potential
The generator potential in turn creates an action potential(nerve impulse) that passes along the neurone and then, via other neurones , to the central nervous system
Where are the light receptors of the eye found
The retina
What are the two types of receptors in the retina
Rod cells and cone cells
Both act as transducers by conserving light energy into the electrical energy of a nerve impulse
why are rod cells images only seen in black n white
As they can’t distinguish different wavelengths of light
What’s the difference in sensitivity to light in rod and cone cells
Rod - sensitive to low intensity light
Cone- not sensitive to low intensity light
What would increase the chance that the threshold value will be exceeded in the bipolar cell
If only w single rod were connected to each bipolar cell
How do we create a generator potential in the rod cell
The pigment in the rod cell must be broken down, there is enough energy from low intensity light to cause this breakdown
Why doe rod cells give low visual acuity
As many rod cells link to a single bipolar cell, light received by rod cells sharing the same neurone will only generate a single impulse travelling to the brain. The brain cannot distinguish between the separate sources of light that stimulated them.
Two dots close together cannot be resolved and so will appear as a single blob
What do the three types of cone cells do
Each respond to a different range of wavelength
Depending upon proportion of each type that is stimulated, we can perceive images in full colour
Why do cone cells only respond to high light intensity
Often have their own separate bipolar cell connected to a sensory neurone in the optic nerve. Meaning that the stimulation of a number of cone cells can not be combined to help exceed the threshold value and so create a generator potential.
