Receptors Flashcards
Receptors
Detects a stimulus (change in environment)
Relationship of receptors to a stimulus
Receptors respond specifically to one type of stimulus
What does receptors being specific to one type of stimulus allow?
Humans can distinguish between different sensations eg temperature and pressure
Because different receptors in the skin can detect them, hence co-ordinate a specific response
Receptors in skin
Large range of different types and vary in number depending on where
Pressure receptors
Can detect changes stimuli in the form of changes in pressure
Example of pressure receptor that is required on the spec
Pacinian Corpuscle
Where is the Pacinian Corpuscle found?
In the skin: fingers, sole of feet, tendons etc
What describes what the Pacinian Corpuscle does overall in response to a pressure change?
Establishes a generator potential
Transducer
Describes the Pacinian Corpuscle as it can transfer energy from one store to another
How do Pacinian Corpuscles act as transducers?
Detects change in pressure via vibrations and transfers energy from mechanical energy to electric energy (can be sent as electrical impulses down sensory neuron)
Are Pacinian Corpuscles cells?
No they are found at ends of sensory neuron axons
Outline of Pacinian Corpuscle structure
Layers of connective tissue called lamellae surround Neuron ending
Gel in between layers contains Na+ ions
Surrounded by a capsule
Neurons membrane contains…
Stretch mediated Na+ channel ion proteins
What happens when to the neuron when Pacinian Corpuscle detects pressure?
The neuron membrane is stretched
What happens when the neuron membrane is stretched?
Deforms stretch mediated Na+ channel ion proteins causing the channel proteins to OPEN
Once the stretch mediated channel proteins open……
Na+ ions from the gel in lamellae can diffuse into the neuron
When Na+ ions diffuse into neuron via stretch mediated channel proteins
This depolarises the membrane
Depolarisation of the neuron membrane
Usually: pos charge in lamellae and neg charge in neuron but once Na+ ions can diffuse into the neuron: the charges are flipped
Depolarisation of the neuron membrane means………
Larger generator potential
When are impulses sent down the neuron as detected by pacinian corpuscle?
If the generator potential is large enough, due to large enough pressure so enough channels are opened and more Na+ ions can diffuse,
a critical voltage called threshold is reached and nerve impulses are sent along the neuron
3 mark description of receptor
Establishes generator potential
Pressure deforms neurone membrane so opening of stretch mediated Na+ channel proteins open and Na+ uses these to diffuse in by FD down electrochem gradient
Greater pressure applied means more channel proteins open = more Na+ diffuses in
