Sensory 2
Terms
undefined, object
copy deck
- sensory receptor classification: traditional
-
sight
hearing
touch
taste
smell
other:
interoceptive (unconscious)
proprioceptors
chemical
thermal
balance - chemoreceptors
- O2, CO2, H+, taste, smell
- mechanoreceptors
- pressure, tension, vibration, position
- electroreceptors
- fish - lateral line (can detect predators in dark)
- magnetic field receptors
- birds, sea turtles, dogs
- thermoreceptors
- heat/cold - pit vipers
- photoreceptors
- vision - pineal eye
- nociceptors
- mechanical, thermal, chemical damage
- superficial
- touch, pressure, flutter, vibration, tickle, warmth, cold, pain, itch
- visceral
- hunger, nausea, distention, visceral pain
- sensory receptor potentials
-
vary with stimulus strength
not all-or-none
must reach threshold to produce an action potential
APS transmit information to CNS - sensory receptor amplification
- can produce electrical signal containing greater energy than contained in the stimulus
- first order neurons
-
primary afferent neurons
peripheral ending functions as sensory receptor or receives input from accessory sensory cell
cell body usually located in dorsal root ganglion or cranial nerve ganglion - second order neurons
-
usually located in spinal cord or brainstem
receives info from first order
transmits to neurons in thalamus
axon usually crosses midline of spinal cord (contralateral) - third order neurons
-
reside in one of sensory nuclei of thalamus
may transform info before transmitting to cerebral cortex - fourth order neurons
-
located in appropriate sensory receiving areas of cerebral cortex
process info further - higher order neurons
-
located in cerebral cortex
process info further
within some unknown site the infor results in perception - slow adapting receptors
- long-lasting stimulus produces prolonged, repetitive discharge in primary afferent neuron
- rapidly adapting receptors
- long-lasting stimulus produces only a short-lived response
- sensory coding
-
modality
location
intensity
frequency
duration - Pacinian corpuscles
-
high frequency vibration
pressure - sclera
-
fibrous coat
gives structure to eye - conjuctiva
- white part of eye
- retina: rods
-
low light
no color - retina: cones
-
sharp images
color - optic disc
-
blind spot
where optic nerve exits eye - Canal of Schlemm
-
scleral venous sinus
drains aqueous fluid
relieves pressure (norm < 22 mmHg) - fovea
-
center of macula
most acute
no rodes - iris
- radially (dilatory) and circulatory (sphincter) oriented smooth muscle