Human Touch and Pain Receptors

Human Touch and Pain
Somatosensory System
• Somoesthetic sensations
– Sensations associated with
skin receptors
• Proprioception
– Perception and position of
the body including limbs
3 Receptor Types
• Mechanoreceptors
– Pressure, force, vibration
• Thermoreceptors
– Temperature
• Nociceptors
– Tissue damaging stimuli
• Modality
– Energy form of stimulus
• Sensory neurons convert energy from stimulus into another
form of energy.
• Receptor potentials
– Graded responses caused by closing and opening of
ion channels.
– Number activated and frequency of APs generated
correlated to stronger stimulus intensity perceived.
• Detect stimuli
• Two main forms:
– Specialized structure on
peripheral end of
afferent neuron.
– Separate cell that
communicates via
chemical synapses with
associated afferent
• Respond to surrounding tissue,
not air temp.
• Warm receptors
– Respond to temps 35-45 °C
– Beyond 45 °C APs decrease rapidly
– Above 45 °C nociceptors also.
• Cold receptors
– Respond to to temps 20-35 °C
– Below 25 °C APs decrease rapidly
– Below 10 °C also nociceptors
– Also respond to temps above 45 °C
• Paradoxical cold receptors
• 3 Types
– Mechanical
– Thermal
– Polymodal
Wet Receptors?
• Brain integrates info
from different sensory
• Combination of
thermoreceptors and
Receptor Density
Body Part
Receptor Density (cm2)
Fingertip, palm surface
60 pain, 100 touch
Back of finger
100 pain, 9 touch
One eye
• Write a methods, results, and introduction.
• Answer ALL questions.
• This may be done within the results section or introduction.
Make sure you include a section with answers to questions that
you don’t answer within the intro or results sections.
• You do not have to replicate the figures from the
pdf for today. Just staple that to your lab report.
• Successfully establishes the physiological
concepts of the lab.
• Effectively presents the objectives and
purpose of the lab.
• States hypotheses AND provides logical
reasoning for them.

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