L20 Principles of sensory systems Flashcards
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
What are sensory receptors proteins?
Sensory receptor proteins are specialized proteins that are located on the surface of sensory neurons or other cells that are specialized to detect stimuli
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
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 kind of stimulus triggers which modality?
- Mechanical stimulus triggers hearing, balance, touch, pain and proprioception
- Light - vision
Thermal - temperature, pain
Chemical - 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
Where is the location of each modality?
Inner ear - cochlea - Hearing
Inner ear - balance
Retina - vision
Skin - touch and temperature
Skin, internal organs - pain
Muscles, tendons and joints: Proprioception
What are the steps in sensory transduction?
Stimulus -> Sesnory receptor is activated -> Membrane permeability altered -> Receptor potential develops -> Neurotransmitters is released onto afferent neuron terminals -> An action potential is generated in the afferent neuron terminal -> The action potential propagates to the CNS -> Information is integrated by the CNS.
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?
Stimulus Intensity is the response amplitude of the receptor and thus the firing frequency of the afferent neurons
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
