SC --> midbrain 1. terminates in midbrain that turns head toward pain 2. activates neurons that project from brainstem to SC to shut off pain pathway

Test 3 Flashcards by Kaylee Farmer

What are the 3 routings of somatosensation?

conscious awareness - cerebral cortex
unconscious - cerebrum
emotional and autonomic - limbic

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Is conscious awareness multi synaptic? Explain.

touch - discriminative
proprioception - “I know where I’ve been touched”
pain - describe and locate
temp - describe and locate

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For the spinal cord tracts, where do sensations of touch and proprioception go?

Back of SC - dorsal columns

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For the spinal cord tracts, where do sensations of pain and temperature go?

anterolateral SC

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Where are discriminative touch and conscious proprioception located?

touch - SC –> dorsal column

proprioception –> brainstem –> medial lemniscus

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Describe the 3 orders of discriminative touch and conscious proprioception.

1st order –> peripheral
sensory receptor
ascends SC into caudal medulla

2nd order –> where fx is contralateral
caudal medulla
crosses to other side
ends in thalamus

3rd order –> to consciousness
synapses in thalamus and heads to the post central gyrus of parietal lobe

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Describe the 3 orders of pain and temperature.

1st order - Free N ending –> dorsal horn
synapse
cross
2nd order - dorsal horn - synapse –> thalamus
3rd order - thalamus to cerebral cortex

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Describe the 3 orders of emotional &and autonomic pathway.

Divergent

can be a 2 or 3 neuron pathway

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What are the three divergent pathways for autonomic and emotional responses?

spinoreticular
spinpmescencephalic
spinoemotional

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spinoreticular

regulates arousal

AWAKE

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spinomescencephalic

SC –> midbrain

terminates in midbrain that turns head toward pain
activates neurons that project from brainstem to SC to shut off pain pathway

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spinoemotional

emotional and autonomic
reactionary
alerts autonomic system

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Where are the divergent pathways located?

Anterolateral column

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parieaqueduct

gray cells around ventricles that send messages back down to sc to modulate pain

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What happens in peripheral sensitization?

sensitization of Free N endings
any injury creates a low threshold for AP
easily activated and slightly depolarized

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What is the first neurotransmitter in the spinothalamic tract?

glutamate - fast

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What is the first neurotransmitter in the divergent pathways?

Substance P
excitatory
prolonged - slow

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Explain the 3 aspects of pain experience.

Sensory discriminative - spinothalamic - look, describe
motivational effective - limbic lobe - spino-emotional and spinoreticular - change mood, change emotion
cognitive-evaluative - experience - prefrontal lobes - cerebral cortex

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Dorsal horn processing - normal

free N endings depolarized - passes along AP

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Dorsal horn processing - suppressed

cannot pass AP as easily
Rubbing suppressed pain synapse
pharmacological

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Dorsal horn processing - sensitized (temporary)

neuropathic

easier for temporary amount of time

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Dorsal horn processing - reorganized - persistent

neuropathic

LTP - increases spines to increase availability to pass signal –> permanent

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I. Periphery

Free N endings - pain receptors
reduce depolarization
stretch, mobilizations, anti-inflammatation, massage

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II. Doral Horn (1st synapse of P pathway)

rub it where it hurts
E stim - depolarizes A-Beta
move to activate mechanoreceptors

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III. Midbrain descending

signal that returns to site

IV. Hormonal - pituatary

autonomic - dumps chemicals into blood to spread to body | endogenous opioids

V. amygdala and cortex

can turn on inferior levels THINK LESS PAIN can turn on endogenous opioids

paresthesia

sensory massage that arises without stimulus of sensory receptors (non-painful)

dysesthesia - allodynia

unpleasant P, spontaneous/evoked alodynia - unpleasant sensation in response to stimulus that is generally not painful (sunburn) \

dysesthesia - secondary hyperalgesia

pain that is out of proportion to stimulus creating it

What causes neuropathic pain?

absence of stimulation in free N endings

What are the four mechanisms of neuropathic pain?

ectopic ephatic central sensitization structural reorganization

Describe ectopic pain

stim. in one place put sensation in another damage to myelination - peripheral axon is killed - injured axon calls for signal - will put ligand/modality gated channels to try and get axon - will now get stimulation inappropriately

Describe ephatic pain

short circuit demyelination between sensation neuron and pain neuron allows a jump of AP = stimulation on pain when sensation reaches threshold

Describe central sensitization.

Learns P When there is a strong or long P signal body reorganizes cell to better receive/transmit P signal so P is increased possible mechanism for hyperalgesia maladaptive - feel pain inappropriately

Describe structural reorganization.

central axon backs off of P neuron and away from synapse 2nd order pain neuron has lost input touch neuron innervates/re-establishes synapse on P

How do central neurons generate Neuropathic P?

If an injured body part receives signal from collateral sprouting. Phantom sensation and phantom pain

General process of Motor System

``` decision to move plan to move control to move motor tracts UMN -SC motor neurons LMN - peripheral ```

myofibril

elongated contractile material in the muscle

sarcomeres

contractors of m z-line: structural end of m m-line: where myosin hangs titin: the rubber band that resists overstretch that may cause damage from one end of sarcomere to other

myofilaments

actin and myosin | actin climbs myosin by way of Ca 2+ to make m contract

How does an AP occur in the muscle

A-Alpha brings All- EPSP- cell is depolarized | if Ca is released- actin climbs myosin, all sarcomere shorten

What causes a contracture?

when titan will not let go of myosin

What may cause total m resistance to stretch? | *****

titin's elasticity has reached it's limit - active contraction actin is continually pulling on myosin- cross-bridges form Number of sarcomeres adapt to length

What does it mean if a muscle contraction is involuntary?

pathological

Where are motor neurons?

begin in cell body of spinal cord and synapse in m

Where are motor neurons located in the cell body?

the ventral horn

In the horizontal organization of motor neurons, what is medial? Lateral? Anterior? Posterior?

medial -- axial and proximal Mm Lateral -- distal Mm Anterior -- extensors Mm Flexors -- Flexor Mm

How is the vertical organization of motor neurons coordinated?

all cell that contribute to a particular M --> cluster into a vertical pool

Which motor neuron contracts M?

A-Alpha

Which motor neuron keeps intrafusal muscle spindles sensitive?

A-gamma

What is the afferent axon from Mm spindles?

What does a motor unit consist of?

1 LMN and all M fibers it connects to

``` Describe what a slow twitch fiber is? size? metabolism? tension? fatigue? ```

small A-Alpha oxidative low tension fatigue resistent

``` Describe fast twitch muscle fibers size? metabolism? tension? fatigue? ```

large A-Alpha glycolytic high tension fatigue in first few moments used

What is the order of recruitment for muscle fibers?

slow twitch first --> fast twitch only called if movement requires strength and power (Hennemans size principle)

Which muscle fibers are easiest to depolarize?

slow twitch small A-alphas

How come we can use fast twitch for more than a few moments if they fatigue so easily?

Our conscious brain changes the demand on which fast twitch muscle fiber is used so they are rotated to reduce fatigue

How does 1 alpha neuron receive information?

convergence brain and sensory receptor deep tendon pressure inhibits alpha 1 neurons

What is a muscle cramp?

no neural input leading to involuntary contraction electrolyte overworked motor neuron dz - fewer motor units - fatigue

What is a fasciculation?

spontaneous depolarization of a motor neuron

myoclonus

whole body jerk

fibrillations

one single m fiber depolarization

paresis and paralysis

paresis - weak - SN | paralysis - inability - PN

disuse atrophy

small, no definition

denervation atrophy

wither away to nothing

hypotonic

loss of some

flaccidity

peripheral N loss - loss of all M tone

"flaccid paralysis"

loss of m tone and inability to contract, damage to motor neuron

Test 3 Flashcards

(69 cards)