Human Touch and Pain Receptors

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 35-45 °C – Beyond 45 °C APs decrease rapidly – Above 45 °C nociceptors also.

Thermoreceptors • 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

Nociceptors • 3 Types – Mechanical – Thermal

– Polymodal

Wet Receptors? • Brain integrates info from different sensory

systems. • Combination of thermoreceptors and mechanoreceptors.

Receptor Density Body Part

Receptor Density (cm2)

Fingertip, palm surface

60 pain, 100 touch

Back of finger

100 pain, 9 touch

One eye

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.