6.2 Nervous System Flashcards
afferent neurons
- transmit into CNA from receptors at their peripheral endings
- single process from the cell body splits into
1) long peripheral process (axon in PNS
2) short central process that enters CNS
efferent neurons
- transmit niformation out of the CNA to effector cells, particularly muscles, glands, neurons and other cells
- cell body with multiple dendrites and small segments of axons are in the CNS
- most of the axon is in the PNS
internuerons
- function as integrators and signal changers
- integrate groups of afferent and efferent neurons into reflex circuits
- lie entirely within the CNS
- account for >99% of all neurons
all pain activates what subcortical level of brain?
reticular formation
somatotopy means?
orderly arrangement of cortical areas that correspond to body areas
is the primary motor cortex or somatosensory cortex more anterior?
primary motor cortex
declarative vs procesdural memory
declarative
- put into words
- short term= hippo and temp lobe
- long term= areas of cortex
- *SWS sleep (short wave)
procedural memory
- how to do things, hand/eye skill
- short term= widely distributed
- long term= basal nuclei cerebellum and premotor cortex
- REM sleep (long wave)
neocortex does what?
causes the hippocampus to replay stuff in slow wave sleep
two examples of neural plasticity?
**what does this do?
1) long-term potentiation
2) neural facilitation
**increases speed, strength and efficiency of synapses and neural transmission
what are the 5 basic sensory receptor types?
1) mechanoreceptors
2) thermoreceptors
3) pain receptors AKA nociceptors
4) photoreceptors
5) chemorecptors
where are the two most common places to find sensory receptors?
1) on fere nerve ending
2) on a receptor cell
what is unique about receptor cells?
NO action potentials on these cells! only graded that lead to action!
divergence vs convergence
divergance= one afferent neuron onto ONE interneurons
convergence= one afferent neuron onto MANY interneurons
changes in membrane permeability generate?
**exception?
depolarizing receptor potential (a graded potential)
** exception is photo-receptor
what two senses have RAPID adaptation?
**Note that all receptors eventually?
olfaction
taste
**All mechanorecptors probably adapt completely given sufficient time, with extinction times ranging from seconds (pacinian corpuscles) to days (aropeceptors)
what is the only receptor that does NOT adapt?
pain
tonic vs rapid adapting receptors
slow adapting (tonic) receptors -continuous input on body status is needed "balance"
rapidly adapting receptors
-monitor rate/movement while it is OCCURING “on or off”
what are the two primary determinates of cnoduction velocity?
1) larger diameter increases velocity
2) more myelination increases velocity
what is the conduction of A-alpha, A-gamma, and C fibers
Aa= 100 m/sec
Ag= 10 m/sec
C= 1 m/sec
what are the two primary sensory pathways in the spinal cord that we will focus on?
1) dorsal column-medial lemniscal pathway
2) anterolateral spinothalamic pathway
what is the proper order of pons, medulla,spinal cord, midbrain?
spinal cord > medulla > pons > midbrain
dorsal column-medial lemniscal pathway transmits information for?
fine touch vibration position movement against skin fine pressure
- large myelinated neurons
- 1st neurons to medulla
- many 3rd order neurons synapse at somatosensory cortex
anterolateral spinothalamic pathway
pain warmth cold crude tactile sensations tickle and itch sexual sensations
- smaller, myelinated neurons
- 1st neuron to dorsal horn
- fewer 3rd order neurons synapse at somatosensory
how much of somatosensory cortex is hand and feet?
40-50%
pathway of DCML?
1) 1st order= post horn to medulla
- –ipsilateral
2) 2nd= medulla, thru lemniscus to thalamus
- –contra
3) thalamus to cortex
pathway of anterolateral spinothalamic sensory pathway?
1) dorsal root to horn
- –ipsilateral
2) immediately cross body! dorsal horn up BOTH anterior and lateral spinalthalmic tracts to terminate in thalamus
- –contra
3) 3rd= FEW to cortex
- – contra
entry of sensory information for the face and oral cavity vs the body/neck/back of head?
- face and oral cavity= enter into the CNS at the pons via trigeminal nerve
- body/neck/back= enter into the CNS at the spinal cord via dorsal nerve roots
where all does joint movement/speed processing happen?
spinal cord, thalamus, and DCML pathway
1) cold receptors
2) warmth receptors
3) pain receptors
1) A-delta
2) C fibers
3) primarily by polymodal nocicetors and C fibers
How is pain classified?
duration
-acuts, subacute, chronic
etiology
-malignent or nonmalignent
initiation
-nociceptive or neuropathic
quality
-A-delta (fast) or C (slwo)
biphasic pain response
- first you get fast pain as A-delta
- secondly you get slow pain from C-fibers
fast pain
A-delta fibers
- rapid
- neospinalthalmic tract of anterolateral pathway
- noxious mechano-stimulation
- unimodal
- intense (sharp or stabbing)
- localized
- NOT felt in deep tissue
slow pain
C fibers
- begins 1 second or more after stimulus
- paleospinalthalmic tract of anterolateral pathway
- noxious mechano-, chemo- and thermo- stimulation
- polymodal
- burn, ache or throb, nausea
- poorly localized
- deep tissue
- tissue destruction and unbearable suffering
what does lidocaine do?
stabilizes the neuronal membrane (preventing depolarization) by inhibiting ionic fluxes required for the initiation and conduction of impulses, thereby effecting local anesthetic action
Lidocaine blocks _______ channels and prevents neural propagation?
voltage-gated sodium channels
*prevents membrane depolarization
takes longer to numb a myelinated or unmyelinated axon?
mylinated! must first spread to nodes of R
central sensitization is an example of?
neuropathic pain
neuropathic pain is the end result of?
pathological neuroplasticity
long term potentiation increases the amount of?
synaptic terminals and dendrites over a long period of time, EASILY ACTIVATED
nociceptive vs non-nociceptive pain?
nociceptive= activate nociceptors which activate central pain areas
non-nociceptive pain= nociceptors are NOT firing, but something else is activating central pain areas
how is central sensitization, sleep deprivation, anxiety and depression related?
they all reinforce each other
central sensitization is initiated by peripheral nociceptors, why can you NOT simply blunt this?
bc it’ll stop learning from happening! You need this to make new short term synapses
define referred pain
pain is percieved at a site that is remote from the noxious stimuli trigger-point (heterotopic pain)
what is the one thing that all functioning theories on referred oain have in common?
afferent convergance
what is the ‘poster child’ for referred pain?
myocardial ischemia
-insufficient BS to heart
