1. Somatic
&
Special Senses
Part 1

2. SENSES Sensory Receptors –
detect environmental changes and trigger nerve impulses
Somatic Senses
touch, pressure, temp, pain
Special Senses
smell, taste, vision, equilibrium, hearing

3. Free nerve endings & Touch receptors
Free nerve endings ( pain, heat, cold movment, superficial) Merkel’s disks (touch!!) superficial
Meissner corpuscles (touch) deep to epidermis Ruffini’s end organs (coninuous pressure, DEEP)
Pacinian copuscles (tendons and joints) pressure

4. Somatic (body) Senses Merkel’s disks: small, superficial. Light touch
Meissner's corpuscles:
deep to epidermis, fine touch
Ruffini’s end organs:
Deep, continuous pressure
Pacinian corpuscles:
deep pressure, tendons and joints
Nociceptors
Temperature Senses
1. Pain: sensations of unpleasant perception (2 types/sharp localized or diffuse, burning)
2.touch, hairless areas of skin (lips, fingertips)
3. deep pressure (tendons, joints)
4. (warm and cold receptors)

5. Sense of Pain
Visceral Pain - occurs in visceral tissues such as heart, lungs, intestine
Referred pain - feels as though it is coming from a different part (heart pain may be felt as pain in arm or shoulder)
Acute Pain - originates from skin, usually stops when stimulus stops (needle prick)
Chronic Pain - dull aching sensation

6. Referred Pain

7. Receptors 1. Chemoreceptors 2. Pain receptors 3. Thermoreceptors
4. Mechanoreceptors
5. Photoreceptors
1. Chemoreceptors = chemical
2. Pain receptors = pain
3. Thermoreceptors = heat
4. Mechanoreceptors = pressure, location
5. Photoreceptors = light

8. CHEMORECEPTORS
Activated by Chemicals
Example: Smell, Taste Receptors

9. Nociceptors Activated by Intense Stimulus That Causes Tissue Damage
Example: Pain Receptors
Pain Initiator: Glutamate, Prostaglandins
Pain Inhibitors: Serotonin, Endorphins

10. Thermoreceptors Activated by Hot/Cold
Example: Hot, Cold Receptors in Skin

11. Mechanoreceptors
Activated by a Stimulus- Deforms or Changes the Position of the Receptor
Example: Pascinian, Meissner, Merkel, Semi-circular canals, Cochlea

12. Photoreceptors Activated by Light
Example: Vision Receptors in retina of eye