Senses and Perceptions 1 Flashcards
What is the structure of a sensory neuron?
pseudo-unipolar
To understand tactile input, what do we need to know?
quality
magnitude
timing; duration
location
What must be considered to understand sensory mechanisms?
Type of receptor (whether it has any histological features)
Transduction of stimulus (how is the signal transmitted)
Stimulus properties (quality, duration, magnitude and location
What receptors transmit pain, temperature and touch?
nociceptor
thermoregulation
mechanoreceptor
What receptors transmit special senses such as vision, taste/smell?
photoreceptors
chemoreceptor
What are free nerve ending receptors usually associated with?
pain; nociceptor
What are examples of mechanoreceptors found in skin?
messiner’s corpuscle
merkel disc
hair follicule receptor
pacinian corpuscle
ruffini ending
What is the distribution of a nerve’s receptor endings coming from peripheral branches called?
receptive field
What does overlapping of receptive regions provide?
full body sensory coverage
Where are receptive fields small and where are they large?
small on the periphery (fingertips)
large on the central/ trunk
What is two-point discrimination concerning the same receptive field?
the sensation will be felt as one point as the same sensory neurone is being activated
What is the sequence of signal transduction?
stimulus applied
change in receptor membrane permeability
influx of cations
depolarisation
action potential
What are the two main types of receptor?
ionotropic (ligand-gated)
G-coupled
What receptors can be ionotropic?
mechanoreceptor
chemoreceptors
What receptors can be G-coupled?
chemoreceptors
What is the difference between ionotropic and G-coupled receptors?
G-coupled receptors induce membrane changes slower than ionotropic which induce them quickly
Why are G-coupled receptors slower?
multiple pathways and proteins must be activated for signal to become transduced
What is stimulus intensity determined by?
number of neurones activated
frequency of AP
What is the stimulus duration determined by?
duration of AP firing
How do slowly adapting axons respond to a stimulus?
AP frequency high at the start however began to tether
How do rapidly adapting axons respond to a stimulus?
lots of AP at the start but none for the rest of duration
What does each receptive field correspond to?
a cortical representation in the brain
Which part of the body has largest sensory homunculus?
The areas of the body that have a higher density of sensory receptors (smaller receptive fields are the hands, face, and tongue.
