1what are tonic receptors?
reecptors that stay activated for duration of stimulus
considered slow adapting
2What are phasic receptors?
rapidly adapt to constant stimulus and turn off
3how are sensory neurons organized?
-organized into receptive fields
-convergence leads to large receptive feilds
4How can a large receptive field be formed?
-when more than one primary sensory neuron overlaps and creates one large secondary receptive field
5What is lateral inhibition?
when a secondary neuron in a receptive field inhibits it's neighboring secondary neurons to channel the stimulus to a single tertiary neuron
6purpose of lateral inhibition?
-enhances perception of simtulus
7What is perceptual threshold?
-level of stimulus necessary to be aware of particular sensation
8What are the two ways that sensation is integrated into CNS?
-sensation transmitted to spinal cord then brain (via ascending pathways)
-sensation transmitted to brain stem (via cranial nerves)
9What is label line coding?
helps us distinguish sensations grouped together
(1:1 association of receptor with sensation)
10what type of reflex does not need conscious perception? where is the stimulus integrated?
-visceral refexes (integrated in brain stem or spinal cord)
11What type of sensations integrate and cross over in the medulla?
-fine touch
-propioception
-vibration
12What type of sensations integrate in dorsal horn and cross over in the spinal cord?
-nociception
-temperature
-coarse touch
13Describe signal pathway of fine touch, propioception, and vibration signals.
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
14Describe signal pathway of nociception, temperature, and coarse touch.
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
15what region of the brain are sensation signals brought?
primary somatosensory cortex
16how is scent interpreted?
-nose to olfactory cortex
17How is vision interpreted?
eye to thalamus to visual cortex
18how is sound interpreted?
ear to thalamus to auditory cortex
19how is taste interpreted?
tongue to midbrain to thalamus to gustatory cortex
20how is equlibrium established?
cochlea to thalamus to cerebellem then primary somatic sensory cortex
21What are the three classes of somatosensory nerve fibers?
-AB (beta)
-Ad (delta)
-C
22structure and role of AB (beta) somatosensory nerve fibers?
large and mylinated
mechanial stimulus
23structure and role of Ad (delta) somatosensory nerve fibers?
small and mylinated
cold
fast pain (itching)
mechanical stimulus
24structure and role of C somatosensory nerve fibers?
-small (unmylinated)
slow pain
heat
cold
mechanical stimulus
25When is substance p released?
in resonse to noxious stimuli
apart of nociception pathway
26speed of somatosensory nerve fibers (fastest to slowest)?
-beta fastest, delta middle, c slowest
27inflammatory response in nociception is mediated by?
-A-delta fibers
-itching (C-fibers)
28What do free nerve endings sense? structure? where are they located?
-hair movement
-noxious stimuli
-temperature
-in dermis and epidermis
-unmylinated
29What do pacinian corpuscles sense? location? structure?
-sense vibration
-single nerve ending encapsulated in layer of CT
-deep within skin
30What do merkel receptors sense? location? struc?
-steady pressure and texture
-in superficial epi
-epidermal cell synapses and enlarged nerve endings
-slow adaptation
31What do meissner corpuscles receptors sense? location? struc?
-flutter and stroking movements
-nerve endings encapsulated with CT
-rapid adaptation
32what somatic sensory fibers have slow adaptation?
-merkel receptors
-ruffini corpuscles
33What is TRP?
transcient receptor potential cation channels