6.2 Nervous System

Question 1

afferent neurons

Answer 1

• 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

Question 2

efferent neurons

Answer 2

• 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

Question 3

internuerons

Answer 3

• 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

Question 4

all pain activates what subcortical level of brain?

Answer 4

reticular formation

Question 5

somatotopy means?

Answer 5

orderly arrangement of cortical areas that correspond to body areas

Question 6

is the primary motor cortex or somatosensory cortex more anterior?

Answer 6

primary motor cortex

Question 7

declarative vs procesdural memory

Answer 7

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)

Question 8

neocortex does what?

Answer 8

causes the hippocampus to replay stuff in slow wave sleep

Question 9

two examples of neural plasticity?

**what does this do?

Answer 9

1) long-term potentiation
2) neural facilitation

**increases speed, strength and efficiency of synapses and neural transmission

Question 10

what are the 5 basic sensory receptor types?

Answer 10

1) mechanoreceptors
2) thermoreceptors
3) pain receptors AKA nociceptors
4) photoreceptors
5) chemorecptors

Question 11

where are the two most common places to find sensory receptors?

Answer 11

1) on fere nerve ending

2) on a receptor cell

Question 12

what is unique about receptor cells?

Answer 12

NO action potentials on these cells! only graded that lead to action!

Question 13

divergence vs convergence

Answer 13

divergance= one afferent neuron onto ONE interneurons

convergence= one afferent neuron onto MANY interneurons

Question 14

changes in membrane permeability generate?

**exception?

Answer 14

depolarizing receptor potential (a graded potential)

** exception is photo-receptor

Question 15

what two senses have RAPID adaptation?

**Note that all receptors eventually?

Answer 15

olfaction
taste

**All mechanorecptors probably adapt completely given sufficient time, with extinction times ranging from seconds (pacinian corpuscles) to days (aropeceptors)

Question 16

what is the only receptor that does NOT adapt?

Answer 16

pain

Question 17

tonic vs rapid adapting receptors

Answer 17

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”

Question 18

what are the two primary determinates of cnoduction velocity?

Answer 18

1) larger diameter increases velocity

2) more myelination increases velocity

Question 19

what is the conduction of A-alpha, A-gamma, and C fibers

Answer 19

Aa= 100 m/sec

Ag= 10 m/sec

C= 1 m/sec

Question 20

what are the two primary sensory pathways in the spinal cord that we will focus on?

Answer 20

1) dorsal column-medial lemniscal pathway

2) anterolateral spinothalamic pathway

Question 21

what is the proper order of pons, medulla,spinal cord, midbrain?

Answer 21

spinal cord > medulla > pons > midbrain

Question 22

dorsal column-medial lemniscal pathway transmits information for?

Answer 22

fine touch
vibration
position
movement against skin
fine pressure

• large myelinated neurons
• 1st neurons to medulla
• many 3rd order neurons synapse at somatosensory cortex

Question 23

anterolateral spinothalamic pathway

Answer 23

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

Question 24

how much of somatosensory cortex is hand and feet?

Answer 24

40-50%

Question 25

pathway of DCML?

Answer 25

1) 1st order= post horn to medulla - --ipsilateral 2) 2nd= medulla, thru lemniscus to thalamus - --contra 3) thalamus to cortex

Question 26

pathway of anterolateral spinothalamic sensory pathway?

Answer 26

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

Question 27

entry of sensory information for the face and oral cavity vs the body/neck/back of head?

Answer 27

* 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

Question 28

where all does joint movement/speed processing happen?

Answer 28

spinal cord, thalamus, and DCML pathway

Question 29

1) cold receptors 2) warmth receptors 3) pain receptors

Answer 29

1) A-delta 2) C fibers 3) primarily by polymodal nocicetors and C fibers

Question 30

How is pain classified?

Answer 30

duration -acuts, subacute, chronic etiology -malignent or nonmalignent initiation -nociceptive or neuropathic quality -A-delta (fast) or C (slwo)

Question 31

biphasic pain response

Answer 31

- first you get fast pain as A-delta | - secondly you get slow pain from C-fibers

Question 32

fast pain

Answer 32

A-delta fibers - rapid * neospinalthalmic tract of anterolateral pathway * noxious mechano-stimulation * unimodal - intense (sharp or stabbing) - localized - NOT felt in deep tissue

Question 33

slow pain

Answer 33

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

Question 34

what does lidocaine do?

Answer 34

stabilizes the neuronal membrane (preventing depolarization) by inhibiting ionic fluxes required for the initiation and conduction of impulses, thereby effecting local anesthetic action

Question 35

Lidocaine blocks _______ channels and prevents neural propagation?

Answer 35

voltage-gated sodium channels | *prevents membrane depolarization

Question 36

takes longer to numb a myelinated or unmyelinated axon?

Answer 36

mylinated! must first spread to nodes of R

Question 37

central sensitization is an example of?

Answer 37

neuropathic pain

Question 38

neuropathic pain is the end result of?

Answer 38

pathological neuroplasticity

Question 39

long term potentiation increases the amount of?

Answer 39

synaptic terminals and dendrites over a long period of time, EASILY ACTIVATED

Question 40

nociceptive vs non-nociceptive pain?

Answer 40

nociceptive= activate nociceptors which activate central pain areas non-nociceptive pain= nociceptors are NOT firing, but something else is activating central pain areas

Question 41

how is central sensitization, sleep deprivation, anxiety and depression related?

Answer 41

they all reinforce each other

Question 42

central sensitization is initiated by peripheral nociceptors, why can you NOT simply blunt this?

Answer 42

bc it'll stop learning from happening! You need this to make new short term synapses

Question 43

define referred pain

Answer 43

pain is percieved at a site that is remote from the noxious stimuli trigger-point (heterotopic pain)

Question 44

what is the one thing that all functioning theories on referred oain have in common?

Answer 44

afferent convergance

Question 45

what is the 'poster child' for referred pain?

Answer 45

myocardial ischemia | -insufficient BS to heart