Human Touch and Pain Receptors

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

Definitions 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.

Mechanoreceptors Detect stimuli Two main forms: – Specialized structure on peripheral end of afferent neuron. – Separate cell that communicates via chemical synapses with associated afferent neuron.

Thermoreceptors Respond to surrounding tissue, not air temp. Warm receptors – Respond to temps °C – Beyond 45 °C APs decrease rapidly – Above 45 °C nociceptors also.

Thermoreceptors Cold receptors – Respond to to temps °C – Below 25 °C APs decrease rapidly – Below 10 °C also nociceptors – Also respond to temps above 45 °C Paradoxical cold receptors

Nociceptors 3 Types – Mechanical – Thermal – Polymodal

Wet Receptors? Brain integrates info from different sensory systems. Combination of thermoreceptors and mechanoreceptors.

Receptor Density B ody Part Fingertip, palm surface Back of finger One eye Receptor Density (cm 2 ) 60 pain, 100 touch 100 pain, 9 touch 90,000,000!!!!!!!!!

Homework!!!! 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.

Introduction 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.