Receptors Flashcards
What receptor do we look at detects changes in mechanical pressure?
Pacinian Corpuscle
Features of the Pacinian Corpuscle
Specific to a single stimulus - mechanical pressure
Produces a generator potential by acting as a transducer
What is a transducer
Something that translates physical or chemical stimuli into electrical or chemical signals which can be processed by the organism
Where is the pacinian corpuscle found?
Deep in the skin
Fingers
Sole of feet
External genetalia
Ligaments
Tendons
From outside to inside, what is the structure of the Pacinian corpuslce?
Capsule
Blood capillary
Layers of connective tissue with viscous gel between
Neurone ending
In what part of the Pacinian corpuscle are the stretch mediated sodium channels found?
In the sensory neurone ending
Why are stretched mediated sodium channels called this?
Because their permeability to sodium changes when deformed
How does the Pacinian Corpuscle work? (Process)
In resting state, stretch mediated sodium channels are closed and so has a resting potential
When pressure is applied to Pacinian Corpuscle, it is deformed and membrane around neurone is stretched
Stretching opens sodium channels in the membrane
Sodium ions diffuse into neurone
Influx of sodium ions depolarises the membrane, producing generator potential
Generator potential turns into action potential, passing along the neurone to other neurones and then to CNS
What 2 receptors can be found in the eye?
Rod cells
Cone cells
Other than receptors, what can the pacinian corpuscle, rod and cone cells be otherwise called?
Transducers
What do rod and cone cells detect?
Light
What can cone cells do that rod cells cannot do + why?
Distinguish different wavelengths of light
Because
3 types of cone cells, 1 type of rod cell
What type of receptor is most abundant in the eye?
Rod cells
How is a generator potential produced in rod cells?
The rhodopsin pigment is broken down in low intensity light, causing a generator potential.
Why do rod cells give poor visual acuity?
Many rod cells are connected to one bipolar neurone.
This means only 1 impulse can be sent to the brain regardless of how many cells are stimulated
The brain therefore cannot distinguish the seperate sources of light
Why can rod cells be stimulated in low intensity light?
Rod cells have retinal convergence
This means there is a greater chance of the threshold value being exceeded which leads to generator potential
What is meant by retinal convergence
Multiple rod cells connected to one bipolar neurone
Where are rod cells primarily found in the eye?
Periphery of the retina
Absent at fovea
Where re cone cells primarily found in the eye?
Fovea
few in periphary
Why is high light intensity required to stimulate cone cells?
Each cone cell has their own bipolar neurone
No retinal convergence
Greater stimulation required to exceed threshold and produce generator potential.
How do cone cells produce a generator potential?
The pigment iodopsin is broken down by high intensity light, producing generator potential.
Why do cone cells have a high visual acuity?
Each cone cell is connected to its own bipolar neurone
Each cone cell produces its own generator potential and impulse to the brain.
Brain therefore can distinguish separate sources of light
