L20 Principles of sensory systems Flashcards
(22 cards)
What are the 3 common steps of conservation of sensory processing across systems?
- Require a physical stimulus
- Sensory receptors in the peripheral nervous system, must transform the stimulus into nerve impulses
- Central nervous system - evokes a response to the signal in the form of perception of sensation
Are sensory receptors just proteins?
Sensory receptors are cells not just proteins
What is sensory transduction?
Converts energy from the environment into the electrochemical signals in sensory receptors
How is specificity for sensory modalities achieved?
Specifity for sesnory modalities is achieved by the structure and position of the sensory receptor.
Name me a few examples of sensory modalities (9)
Vision
Smell
Taste
Hearing
Balance
Proprioception (sense where your body’s position is. For example arm being bent or straight)
Touch
Thermal senses
Pain
What is the difference between graded receptor potential and action potential?
- Graded receptor potentials increase in size in response to increases in stimulus amplitude
- Action potentials are always the same size, but have a threshold for activation
What receptor is needed for each modality?
- Hearing - mechanoreceptor
- Balance - mecahnoreceptor
- Vision - Photoreceptor
- Touch - Mechanoreceptor
- Temperature - thermoreceptor
- Pain - Nociceptor
- Proprioception - mechanoreceptor
- Smell (olfactory) - chemoreceptor
- Taste - chemoreceptor
Where is the location of each modality?
Vision - retina
Touch - skin
Hearing - inner ear (cochlea)
Olfactory (smell) - nasal cavity
Taste - Tongue, pharynx, palate
Balance - inner ear
Proprioception - muscles, tendons + joints
Temperature - skin
Pain - skin, internal organs
Give an example of a direct neuronal activation
Olfactory receptors (detecting odor molecules)
How does a graded receptor potential develop in a cilium?
Ion influx causes membrane depolarisation and a graded receptor potential develops in a cilium.
Give an example of neuronal activation including synapse.
Taste receptors
What are the four types of information that sensory receptors convey?
- Modality
- Location
- Intensity
- Timing
What are the features of labelled line code?
- The receptor is selective for one type of stimulus energy
- The axons of the receptor/associated afferent neuron acts as a modality specific line of communication
- Axons from these neurons make connections with specific areas in the CNS
What are the features of stimulus location?
- Spatial arrangement of activated receptors within a sense organ gives information about the stimulus.
- In somatic system, a receptive field is the region of skin innervated by the terminals of the receptor neuron.
- In visula system, a receptive field of a photoreceptor is the region of the visual field projected onto that receptor.
What is stimulus intensity?
Intensity is the total amount of stimulus energy delivered to the receptor
What is onset timing determined by?
Onset timing is determined by when the stimulus energy is received by the receptor and causes it to fire
What is the difference between slowly adapting receptors and rapidly adapting receptors?
Slowly adapting receptors:
* Tonic receptors (continuous action potentials)
* Respond to prolonged stimulation.
Rapidly adapting receptors:
* Phasic receptors
* Respond at the beginning and end of a stimulus.
What is the stimulus duration determined by?
Stimulus duration is determined by adaptation (Adaptation = In response to continuous stimuli, the firing rate of action potentials decreases) rates of receptors
What is the lowest stimulus strength known as?
Sensory threshold
What is intensity determined by?
It’s determined by the response amplitude of the receptor and thus the firing frequency of the afferents neurons
What are tonic receptors?
They are slowly adapting receptors which respond to prolonged stimulation
What are phasic receptors?
They are rapidly adapting receptors which respond at the beginning and end of a stimulus
