Neurophys part 2 Flashcards
Type of stimulus that activates merkel and ruffini
Steady pressure
Type of stimulus that activates meissner and pacinian
vibration, which causes tingling sensation
location of meissner and merkel
epidermis
location of pacinian and ruffini
dermis
Sensitivity of meissner and merkel
sensitive- activate with smaller stimuli
Sensitivity of pacinian and ruffini
lower sensitivity, activate with more stimuli
precision of meissner and merkel
more precise, smaller receptive field
Precision of pacinian and ruffini
less precise, larger receptive field
Which receptors are tonic/phasic
Tonic: merkel and ruffini (continued sensation like pressure/vibration)
Phasic: meissner and pacinian(rapdily adapt- wearing clothes)
How does the brain know the difference between light and hard touch
AP frequency increases with harder and stronger touch
What are mechanical nocioceptors stimulated by
sharp and high pressure
What are chemical nocioceptors stimulated by
H+ ions, bradykinins
What are thermal nocioceptors stimulated by
cold: <20C
hot: >40C
What are fast pain nocioceptors stimulated by and what neurotransmitter is involved
a gamma fibers, glutamate
What are slow pain nocioceptors stimulated by and what neurotransmitter is involved
chronic pain- c fibers
glutamate and substance p
What is hyperalgesia
Increased pain from a normally painful stimuli (I.e. piniching is normally painful, but even more painful abnormally so)
What is allodynia
Pain from a sitmulus that doesnt usually cause pain (i.e. touching skin over broken bone- touching doesn’t usually cause pain, but does)
What cells do injured cells release
Prostaglandins, 5-HT, K, bradykinin, histamine
What is the pain-spasm cycle
first tissue damage leads to pain, pain leads to muscle spasm, spasm causes more pain, more pain causes more spasm
What is visceral/deep pain?
Very excruciating, diffuse, not localized, due to organ damage usually. C fiber driven
What is referred pain?
Shared secondary neuron, brain interprets pain from wrong region
What is phantom limb pain?
Regions of thalamus that once recieved input from amputated limb recieves input from stump, but brain interprets it as limb
- Remapping can occur- pain from amputated limb ends up elsewhere (i.e. face)
What type of pain does convergence theory relate to
referred pain
What is a form of automatic splinting
pain that leads to a muscle spasm (connected to pain-spasm cycle, where tissue damage leads to pain and then to muscle spasm, which is a form of automatic splinting)
What is the primary sensory processing part of the brain
parietal lobe
What is the size of the sensory processing region in the brain related to
1.the number of receptors and neurons in the region.
- That dictates the sensitivity of an area on the body.
What effects do opoids have on the neurons in the spinal cord (dorsal root ganglion)
- Decrease Ca influx, lead to NT release
- Hyperpolarizing membrane of spinothalamic tract neuron by increasing K+ efflux
What is gate theory of pain?
If Large nerve fibers are strongly stimulated, these are passed to the brain over weaker signals from small nerves (like pain nerves)
Opioid actions in spinal cord inhibit ascending pain signals
what is the pathway for olfactory sensing
odarant binds to receptor, activates G-protein, activate adneyl cyclase, activate cAMP, open Na/Ca channel–> depoarization (smell!)
Where do you get conscious descrimination of smells
orbitofrontal cortex
Where are smells connected to emotions
amygdala
Where are smells connected to memories
entorhinal cortex
Where are smells connected to pheromones
vomeronasal organ
Where are taste buds/how many
5000, on papillae, soft palate, epiglottis, pharynx
What are tastants and how do we sense them
dissolve in saliva, then into pore, then onto microvilli receptors
Simple gustatory pathway
Cn 7 (facial nerve) (anterior 2/3 of tongue), CN 9 (glosopharyngeal n )(posterior 1/3 tongue), CN 10 vagus (all the other places)
–> medulla–> thalamus–>gustatory cortex
Which tastes use metabotropic receptors
sweet, bitter, umami
Which tastes use ionotropic receptors
salty, sour
Which tastes are we most sensitive to
bitter tastes
How does pupilary constriction occur
via parasympathetic activation
- CN 3 (occulomotor) contracts sphinctor muscle
How does pupilary dialation occur
inactivate CN3 (occulomotor)- relaxes pupilary sphinctor m
Where are cones of retina located
fovea centralis of retina- directly behind pupil- where we want focal point of light to hit retina-
Where is the blind spot in the eye
point where optic nerve (2) leaves eye- no photoreceptors
Where are rods in the eye
periphery/sides of eyeball, low resolution
What kind of fluid does anterior chamber hold
aqueous humor
What secretes aqueous humor
cilliary processes
What is the pathophys of glaucoma
interference of reabsorbtion of aqueous humor–> increased intraocular pressure–> potential damage to retina/optic nerve
