Lecture 7 Flashcards
what is stimulated by mechanical desplacement of tissue
mechanoreceptive somatic senses
what detects heat and cold
thermoreceptive somatic senses
what is activated by any factor that damages the tissue
pain somatic senses
sensations from the surface of the body
exteroceptive sensations
what has to do with the physical state of the body including position sensations, tendon and muscle sensations, pressure sense from the bottom of the feet, and even sense of equilibrium
proprioceptive sensations
sensation from those of the internal organs of the body
visceral sensations
sensations that come from deep tissues such as fascia, muscle, and bone. mainly include deep pressure, pain, and vibration.
deep sensations
what results from the stimulation of touch receptors in the skin or tissues immediately beneath the skin
touch sensation
what results from deformation of deeper tissues
pressure sensations
what results from rapidly repetitive sensory signals, however, some of the same receptors for touch and pressure are used
vibration sensations
types of tactile receptors
glaborous skin
hairy skin
what is glaborous skin
hairless skin
superficial
detect touch and pressure on glaborous skin
free nerve endings
superficial
tapping and low frequency vibration in glabrous skin
meissner’s corpuscles
superficial
touch or well localized pressure on glabrous skin
expanded tip receptor
deep
poorly localized touch and pressure (glaborous)
ruffini’s endings
deep
vibration (glaborous)
pacinian corpuscles
superficial
vibration (glaborous)
krause’s corpuscles
superficial
touch and pressure (hairy skin)
free nerve endings
superficial
touch or well localized pressure (hairy skin)
expanded tip receptors
deep
vibration (hairy skin)
pacinian corpuscles
superficial
light touch and low frequency vibration (hairy skin)
hair follicle endings
order of receptors from closest to skin to deeper
free nerve endings
meissner corpuscle
merkel cell
ruffini
pacinian corpuscle
a resting membrane potential and areas is ______, this sents action potential, and it is scent down the line toward the brain.
deformed
two possibilities of transmission of intensity by receptors
spatial summation
temporal summation
what is spatial summation
signal strength is determined by the number of fibers stimulated, and the area that the stimulus overs
what is temporal summation?
frequency of stimulation of a single fiber or group of fibers increases intensity of sensation
classification of peripheral nerve fibers is based on what 2 characteristics?
degree of myelination
conduction velocity
what are the 2 classifications of peripheral nerve fibers
motor fibers - I, II, III, IV
- (away from brain)
cutaneous fibers - Aα (alpha), Aβ (Beta), Aδ (lowercase Delta), C
- (toward brain)
afferent nerve fibers are
toward the brain
Aα and Aβ
- myelination?
- Conduction velocity?
- modality?
heavily myelinated
very fast (30-120 m/sec)
mechanoreception cutaneous, muscle
Aδ
- myelination?
- Conduction velocity?
- modality?
finely myelinated
fast (5-15 m/sec)
mechanoreception pain, temperature
C
- myelination?
- Conduction velocity?
- modality?
unmyelinated
slow (0.2-2 m/sec)
Pain, Temperature
Pain can be elicited by _______, ______, and _____ pain stimuli
mechanical
thermal
chemical
_______ stimuli detects extremes of temperature-freezing cold or burning hot above ___ degrees C
thermal
45 degrees C
______ stimuli involves intense tissue damage causing release fo chemicals that enhance the sensitivity of pain sensing free nerve endings.
chemical
an increase in the sensitivity of pain receptors is called ______
hyperalgesia
pain is detected/transmitted through _____
nociceptors
what are nociceptors
free nerve endings
responds to potentially damaging stimuli
what prevents the individual from “forgetting” the potential tissue damage that is occuring
diminish perception
types of nociceptors
C-polymodal nociceptors
A-delta nociceptors
Silent or mechanically insensitive nociceptors
C-polymodal nociceptors
unmyelinated
CV=0.5-2 m/s
types of stimuli that elicit a response for c-polymodal nociceptors
noxious mechanical
noxious thermal (above 45 degrees C)
noxious chemical
C-polymodal nociceptors sensations are felt as ?
dull, deep, burning, or aching, poorly localized pain
fast pain
- stimuli?
- speed and fibers?
- responsible for?
mechanical or thermal stimuli
A Delta fibers at relatively high velocity (6-30 m/s)
responsible for immediate reaction (retraction)
slow pain
- stimuli?
- speed and fibers?
- responsible for?
chemical or persistent stimuli of mechanical or thermal signals
C fibers slow (0.5-2 m/s)
chronic pain, tends to increase over tine, urging a person to remove from the stimuli (walk away not just retract)
warm and cold thermoreceptors fire in ______ but _____ temperatures.
when are we aware/ not aware of this firing?
different but overlapping
not aware when continuously firing at normal temperatures (tonically active)
aware when we experience a change in firing frequency
direct pathways, called the ______ theory, meaning well localized in ____ traveling in anatomically discrete regions that can be specifically injured.
labelled line theory
interruption of direct pathways cause ______
immediate sensory deficits
somatosensory pathway is a ____ neuron system
three
what is the function of somatosensory primary sensory neuron?
transducer sensory information and sends it to the ipsilateral (same side) side of CNS
for somatosensations of the BODY, cell bodies are located in the ______ with their central projections entering the _____ through the _____
BODY
dorsal root ganglion
spinal cord
dorsal root
for somatosensations of the HEAD, most of the cell bodies are located in ________ of the _____ with their central projections entering through the _______.
trigeminal ganglion
of the pons
trigeminal root
what occurs in second order projection neurons?
synapses with primary sensory neuron at the firs relay station
- this neurons axon crosses the midline and then projects to the contralateral thalamus
what occurs with the third order neuron station?
synapses with the second order neuron
- their axons enter the internal capsule and do not cross midline
- the axon projects to the somatosensory cortex
two somatic sensation systems
dorsal column medial lemniscal system
anterolateral systen
dorsal column-medial lemniscal somatic sensation system
- discrete mechanoreceptive
- touch require high degree of localization
- touch requiring fine graduation of intensity
- phasic sensations (vibrations)
- movement against the skin
- position sensation from joints (proprioception)
- fine grades of pressure intensity sensation
- fast/highly myelinated
dorsal column-medial lemniscal pathway
sends info from a peripheral receptor to the cerebral cortex over a pathway of three neurons
dorsal column-medial lemniscal pathway transmits _______ stimuli from the ______
conscious perception of tactile, vibratory, and proprioceptive stimuli
from the body and posterior 1/3rd of the head
first order neuron of the dorsal column pathway
heavily myelinated with high CV
- from peripheral mechanoreceptors into the spinal cord.
- through ipsilateral dorsal columns.
-synapses with second order are in medulla
second order neurons of the dorsal column pathway
from caudal medulla
-axons of gracilis and cuneatus tracts synapse in caudal medulla
- cross (decussate) the midline and ascend through the contralateral brainstem forming the medial leminiscus
third order neuron in dorsal column pathway
originates in thalamus
- axons of the medial lemniscus synapse with third order neurons
- axons project to the primary somatosensory cortex
what is the thalamus
a primary routing organ that send information to the sensory cortex
- accommodation of thalamus to gross sensation can occur after cortical damage (send info to other system)
there is a large ______ extending diagonally across the brain
central sulcus (fissure)
immediately _____ to the central sulcus is known as the _________, which recieves ____ information from_________. This info is sent ________ for ________.
posterior
primary somatosensory cotex
crude
all sensory modalities
to the higher order surrounding associational cortices
for further processing and interpretation
the portion of cerebral cortex anterior to the central sulcus is the________
primary motor cortex
each hemisphere has a ____ cortex and ____ cortex area. Each hemisphere has charge of ______
somatosensory cortex
motor cortex
one side of the body
The lateral aspect of somatosensory cortex receives info for ________.
face
hand
arm
The central aspect of somatosensory cortex receives info for ________.
trunk
hip
The medial aspect of somatosensory cortex receives info for ________.
leg and foot
typically lesions in the lower cervical and upper thoracic cord will affect sensations of the ______
upper limbs
lesions of the lumbar cord will usually affect sensations of the ______
lower limbs
anterolateral system characteristics
- broad spectrum of sensations
- pain
- thermal sensation
- gross south and pressure sensation (poor at localization)
- tickle and itch
- sexual sensations
- slower/less or not myelinated
Anterolateral system description
sends info from peripheral receptor to the cerebral cortex thru spinothalamic fibers with three neurons.
what does the anterolateral system transmit?
the discriminatory component of info regarding noxious (pain) and thermal stimuli from the body and posterior 1/3rd of the head
first order neuron of the anterolateral system
originates in the dorsal root ganglion
- info from nociceptors and thermoreceptors into spinal cord gray matter
- where its axons synapse with the second order neurons of the spinal cord dorsal horn
second order neuron of anterolateral system
originate in spinal cord dorsal horn
- across midline at the same spinal cord segment they came in
- the fibers ascend through the anterolateral quadrant of the contralateral spinal cord
- synapse with the third order neurons in the thalamus
third order neurons of the anterolateral system
originate in the thalamus
- their axons through the posterior limb of the internal capsule to the primary somatosensory cortex
ALS is located in the __________ of the spinal cord
anterolateral white matter
what are the three tracts of the anterolateral system?
spinothalamic tract
spin-reticular fibers
spinotectal fibers
what is the spinothalamic tract of the ALS
transmits location, intensity, type of pain.
- the affective component activates the autonomic nervous system (fight or flight)
what is the spin-reticular fibers of the ALS
take same course as spinothalamic fibers, but this order neurons go to reticular formation of brainstem.
- the thalamus sends the info to a number areas including limbic system (emption formation)
what is the spinotectal fibers of the ALS do ?
take same course as spinothalamic fibers except project to midbrain and pons to the raphe nucleus to the dorsal horn of spinal cord.
- these fibers inhibit pain transmission
fast pain or first pain is described as a _________ pain felt within ____ after a pain stimulus is applied
sharp
pricking
acute
electric pain
0.1 sec
fast or first pain is felt in more _____ tissues as a result of tissue trauma and is elicited by a ____ or ______ stimuli.
superficial
mechanical or
thermal noxious stimuli
fast or first pain is transmitted in the ___________ to the spinal cord by type ____ fibers at velocities between ___ and ____
peripheral nerves
A(delta) fibers
6-30 m/s
slow pain or second pain is describes as _________ pain felt within ___ of the stimulus
slow burning
aching
throbbing
nauseous
chronic pain
1 sec
slow pain is usually associated with _____________ and can occur in _____ tissue
tissue destruction
skin and deep tissue
slow or second pain is elicited mostly by _____ types of pain but sometimes by _____ or _____ stimuli
chemical
mechanical
thermal
slow or second pain is transmitted to the spinal cord by __________ at velocities _________
C-polymodal fibers
0.5-2 m/s
because of this double system of pain innervation (dorsal column and anterolateral) a sudden painful stimulus often gives us a double pain sensation of ___________
fast sharp pain followed by slow throbbing pain
pain from the internal organs of the abdomen and chest that stems from visceral inflammation, visceral infectious disease, and other visceral alignments
visceral pain
how does visceral pain differ from surface pain
- pain is poorly localized and not always percieved
- strong stimuli can induce radiation of pain from considerable distances
- pain is frequently referred to skin surface
- results from diffuse stimulation of nerve fibers
a person feels pain in a part of the body that is fairly remote from the tissue causing the pain is called
referred pain
example of referred pain
visceral pain fibers are stimulated, so are the neurons that conducted pain signals from the skin. Person feels that the pain is in the skin itself
cutaneous territories for referred visceral pain
C3-C4 = lungs,diaphragm
T1-T8 = heart
T10 = appendix
T10-T12 = testes, prostate, ovaries, uterus
sacral = bladder
when a pain nervous pathway becomes excessively excitable and produced hypersensitivity to the pain.
what is hyperalgesia
hyperalgesia occurs at ______ and becomes tender after the injury
site of injury
skin becomes tender
primary hyperalgesia
from increased sensitivity of nociceptors
- sunburned skin
secondary hyperalgesia
results from increased sensitivity of sensory transmission
(result of central sensitization)
herpes zoster (shingles)
- viral infection of the dorsal root ganglion
- causes severe pain in the dermatomal segment that encircles halfway around the body
- causes a rash that vesiculates and then crusts over within a few days
sharp pain over one side of the face in the sensory distribution area of DN V or IX and Results from hypersensitivity of the area served by these nerves.
Tic Douloureux
(also called trigeminal neuralgia or glossopharyngeal neuralgia).
Tic Douloureux pain fells like a _______. Can be set off by exceedingly sensitive trigger areas of the face such as __________
sudden electric shocks
face, mouth, or inside throat
Tic Douloureux treatment
carbamazepine (tegretol) - anti seizure med
or rarely, remove sensory nerve
what helps descend or modulate pain In the body and how?
enkephalins and endorphins
- neurons in midbrain and upper pons send signals to raphe nucleus in lower pons and upper medulla
- raphe nucleus sends second order signals down the dorsolateral columns of spinal cord and into pain inhibitory complex in the dorsal horn
- here these axons can suppress signals being transmitted in the dorsal spinal column
Opiates: such as morphine are thought to activate the _________ system by increasing activity in the signaling areas of the _____________. By increasing activity in the _________ we see a reduction in pain.
- analgesia
- lower pons and upper medulla
- descending pain modulatory system
how can opiates be applies?
systematically
- oral medication
on the spinal cord
- epidural
- intrathecal (patch that releases it into skin slowly)
Stimulation of A(beta) sensory fibers from the surface of the skin can _________. likely a result of ______________. example?
decrease pain deeper under skin
local inhibition
rubbing skin can relieve pain
electrical stimulation involves _____ being placed on the skin or in the spinal cord, which stimulate _______ and reduce pain. however when u stop, ______
electrodes
dorsal sensory columns
the pain comes back
