Sensory Physiology

reecptors that stay activated for duration of stimulus
considered slow adapting

rapidly adapt to constant stimulus and turn off

-organized into receptive fields
-convergence leads to large receptive feilds

-when more than one primary sensory neuron overlaps and creates one large secondary receptive field

when a secondary neuron in a receptive field inhibits it's neighboring secondary neurons to channel the stimulus to a single tertiary neuron

-enhances perception of simtulus

-level of stimulus necessary to be aware of particular sensation

-sensation transmitted to spinal cord then brain (via ascending pathways)
-sensation transmitted to brain stem (via cranial nerves)

helps us distinguish sensations grouped together
(1:1 association of receptor with sensation)

-visceral refexes (integrated in brain stem or spinal cord)

-fine touch
-propioception
-vibration

-nociception
-temperature
-coarse touch

primary neuron innervates in dorsal horn of spinal cord and up into medulla of midbrain, secondary sensory neuron carries signal and crosses over to opposite side of thalamus, tertiary sensory neuron takes signal to primary somatic cortex

primary sensory neuron enter dorsal horn of spinal cord, secondary sensory nerve crosses over in spinal cord and passes through midbrain into thalamus, tertiary sensoyry neuron takes signal to primary somatosensory cortex

primary somatosensory cortex

-nose to olfactory cortex

eye to thalamus to visual cortex

ear to thalamus to auditory cortex

tongue to midbrain to thalamus to gustatory cortex

cochlea to thalamus to cerebellem then primary somatic sensory cortex

-AB (beta)
-Ad (delta)
-C

large and mylinated
mechanial stimulus

small and mylinated
cold
fast pain (itching)
mechanical stimulus

-small (unmylinated)
slow pain
heat
cold
mechanical stimulus

in resonse to noxious stimuli
apart of nociception pathway

-beta fastest, delta middle, c slowest

-A-delta fibers
-itching (C-fibers)

-hair movement
-noxious stimuli
-temperature
-in dermis and epidermis
-unmylinated

-sense vibration
-single nerve ending encapsulated in layer of CT
-deep within skin

-steady pressure and texture
-in superficial epi
-epidermal cell synapses and enlarged nerve endings
-slow adaptation

-flutter and stroking movements
-nerve endings encapsulated with CT
-rapid adaptation

-merkel receptors
-ruffini corpuscles

transcient receptor potential cation channels