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What somatic sensations are part of the PNS?
- Somesthetic (skin)
- Proprioception (limbs/body position)
What special senses are part of the PNS?
What is a sensory receptor?
Specialized nerve ending or seperate cell that detects a sensory stimulus.
What are the different classifications of sensory receptors?
What is transduction
Conversion of stimulus energy to electrical energy
What is the Law of Specific Nerve Energies?
- Receptors show specificity to one modality
- Ex. nerves in tongue cannot smell
Define receptor potentials
Change in membrane potential in response to a stimulus acting on a sensory receptor
What are some properties of receptor potentials?
- Caused by opening/closing of ion channels
- > threshold can generate AP
- 1. Sclera
- 2. Cornea
- 3. Choroid
- 4. Ciliary body
- 5. Iris
- 6. Retina
- 7. Fluid filled
What are the 3 components of the iris?
- Constrictor - inner circular muscle
- Dilator - outer radial muscle
- Pupil - opening in the center
Where are rods and cones present in the greatest amounts in the retina?
- Cones: fovea, and periphery
- Rods: beside fovea, and periphery
How are the 4 different opsins distributed?
- Rods - 1 (black/white)
- Cones - 3 (red, green, blue)
What is the difference btwn rods and cones?
- Rods - high sensitivity to light, scotopic vision (night)
- Cones - low sensitivity to light, photopic vision (day)
What 3 combinations of color cancel e/o?
What is rod "bleaching"?
- Exposure to light
- Retinal seperates from opsin
- No more light can be absorbed
- Move to dark, retinal & opsin reassociate, can see again