Somatic & Special Senses Part 1

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

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

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)

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

Referred Pain

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

CHEMORECEPTORS Activated by Chemicals Example: Smell, Taste Receptors

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

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

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

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