Basic Sensory System Flashcards
What forms of stimulus energy can be detected?
- mechanical
- chemical
- thermal
- optic
What stimulus features are encoded by the sensory system?
- modality
- spacial information
- intensity
- quality
What do accessory structures do?
Play an important role in determining how stimulus energy gets to the transducing cells, can be cellular or non cellular
What don’t accessory structures do?
- do not transduce stimulus energy
- are not neurons or receptor cells
What is the labelled lines concept?
Refers to each sensory receptor having its own unique pathway from the periphery through to the somatosensory cortex where we can perceive and localise that sensory information
What is an assumption of the labelled lines concept?
It doesn’t matter where along the pathway action potentials are generated
What is the bionic eye based on?
The labelled lines concept
What is somatosensation?
The process that conveys information regarding the body surface and it’s interaction with the environment
What are the 4 modalities of somatosensation?
- touch
- nociception
- temperature
- proprioception
What are the classes of thermal receptors?
Cold and warm
What happens when temperatures are at extremes?
Pain sensation instead of warmth or cold
Where does the greatest stimulation of thermoreceptors come from?
The initial change in temperature
What do nociopceptors respond to?
Thermal, chemical and noxious stimuli
What are the classes of nocireceptors?
Group A delta
Group C fibres
Group A delta nocireceptors
- small diameter unmyelinated fibres
- fast sharp pain from mechanical or thermal nociceptors
- small receptive field means precise location of pain
Group C nocireceptors
- small diameter unmyelinated
- slow dull pain from mechano, chemical and thermal stimulation
- large receptive field means less precise localisation of pain
What are the types of cutaneous mechanoreceptors?
- Merkel’s receptor
- Meissner’s corpuscle
- Pacinian corpuscle
- Ruffini’s corpuscle
Merkel’s receptor
- close to surface of skin
- light sustained touch
Meissner’s corpuscle
- close to surface of skin
- light fluttering touch
Pacinian corpuscle
- located more deeply
- vibration and deep pressure
Ruffini’s corpuscle
- located more deeply
- deep pressure
What does the ability to distinguish between two spatially different stimuli depend on?
- density of receptors
- size of receptive field
- central convergence and lateral inhibition
What must happen to distinguish between two points?
They must fall within two different receptive fields
How does lateral inhibition work?
- inhibitory neurons
- stimulus from receptors must be greater that stimulus from inhibitory neurons
- stimulus is weaker on periphery - therefore inhibitory neurons override
