Nervous System 7 Flashcards
________ are on free nerve endings & commonly found in the skin. Also in hypothalamus, spinal cord, & deep tissues.
Thermal Receptors (thermoreceptors)
There are _____ times as many cool receptors at any skin
3-10
____ signals are transmitted by C and A delta fibers
Warm signals
____ signals are transmitted by A delta and C fibers
Cool signals
Which signals use more A delta fibers?
Cold signals
_______ channels have been identified, each sensitive to a different temperature range. Some chemicals (Capsaicin, Menthol) elicit thermal sensations, too.
Transient Receptor Potential (TRP)
Temperature increases the rate of intracellular chemical reactions > 2 times per ____ degrees Celsius change
10 degrees
Tickling, Pricking, Aching, Burning, Numbing are considered ____ pain
COLD PAIN:
Sharp, Pricking, Stinging, Burning, Throbbing are considered ____ pain
HOT PAIN:
IS the adaptation of thermoreceptors phasic or tonic?
Phasic
T/F: If the temp reaches one of the pain thresholds, the sensation becomes. more persistent throughout the stimulus
True
Warm and Cool receptors are best able to detect a change at the _____ range of their temperature sensitivity (that is where they are most sensitive)
mid-range
T/F: If nociceptors are simultaneously activated, the system is even better able to discern small changes in temperature
True
As temperature increases (or decreases) within a range of a thermoreceptor’s sensitivity, _____ (more or less) receptors are activated, based on their varying thresholds
more and more
The greater the area of skin affected by a thermal stimulus, the ______ the number of receptors, receptive fields, and first order neurons activated and thus the _____ the perceived sensation.
greater
There is a much _____ ability for detection of a temperature stimulus if a large region is activated.
greater
Receptors in the oral cavity are primarily sensitive to _____ but certain ones are sensitive to chemicals
Temp
____ receptor subtype: 1.TRPV1 Receptor 2.Activated by capsaicin, temperature >43°C, and protons3.Decreases the threshold of channel activation so that heat is perceived at 33°C.
Vanilloid Receptor Subtype
______ receptor subtype: 1.Menthol and related compounds2.Decreases the threshold of the channels so that warmer compounds are perceived as cold.
Cold-Menthol Receptor Type I (CMR1/TRPM8)
Small receptive fields _____ acuity
increase
Are there more cool or warm receptors in the oral cavity
Cool
Which sensation is better at accurately detecting thermal increments?
Warm
Thermoreceptors in ____ are the most sensitive to changes in temperature.
tongue
Due to activation of nociceptors. This usually results in the perception of PAIN, an unpleasant & emotional experience associated with actual or potential tissue damage.
NOCICEPTION
T/F: All nociception produces pain, though not all pain results from nociception.
True
_____ whatever its cause, is never benign. ____ is the most common reason patients seek healthcare AND the most common symptom of disease.
PAIN
T/F: Pain is polymodal and can be evoked by any stiumuli
True
____ pain: Physiologic Pain; <6 months duration
ACUTE
____ is a form of acute pain From skin, subcutanous tissues or mucus membranes (Superficial) or muscles, tendons, joints or bones (Deep).
Somatic:
____ is a form of acute pain Due to a disease process or abnormal function involving an internal organ (Visceral) or its covering (Parietal).
Visceral:
____ somatic pain is localized, sharp, pricking and burning
Superficial Somatic:
_____ somatic pain is dull, aching, diffuse and can be referred
Deep Somatic:
____ visceral pain is dull, diffuse, poorly localized and associated with nausea and autonomic symptoms.
True Visceral:
____ visceral pain is sharp, stabbing and better localized than true pain.
Parietal Visceral
_____ pain happens when two nociceptive afferent neurons—from different regions of the body—converge on the same second order neuron. The brain doesn’t know which is the true source of input and may make a mistake in interpretation.
Referred pain
____ pain Pathologic Pain; occurs beyond the usual course of an acute disease or after a reasonable time for healing to occur
CHRONIC
Due to activation of nociceptors
Nociceptive
Due to neuronal injury•Pain is paroxysmal, sharp and stabbing•Pain is associated with Hyperalgesia
Neuropathic:
(increased sensitivity to pain)
Hyperalgesia
____ receptors are usually found on free nerve endings and are sensitive to mechanical, thermal, and chemical stimuli
Nociceptors
Chemicals known to _____ nociceptors: Substance P, ATP, calcitonin gene related peptide (CGRP), glutamate, aspartate, Bradykinin, potassium, Histamine, serotonin
excite
Chemicals known to _____ nociceptors: Substance P,Prostaglandins, Histamine, Bradykinin
sensitize
Chemicals known to _____ nociceptors: Enkephalins, β Endorphin, Cannabinoids
inhibit
Minimal adaptation and a nociceptors activity actually _____ if the painful stimuli continues (hyperalgesia) due to nociceptor sensitization.
INCREASES
(painful sensation to a innocuous stimulus)
Allodyina
Summation of nociception is _____ (based on # of receptors activated).
spatial
Stimulation of nociceptors also leads to antidromal (reverse) activation of nociceptive nerve terminals and release of substance P and calcitonin gene related peptide. Release of these peptides causes mast cell degranulation, vasodilation and edema, and further sensitization and activation of nociceptors
Neurologic inflammation
The _____ includes red flush (flare), local tissue edema, and sensitization to noxious stimuli
Triple response
____ fibers transmit pain in CNS that is small and myelinated; neurotransmitter includes glutamate; sharp localized pain; thermal and mechanical stimuli
A-delta fibers
____ fibers transmit pain in CNS are unmyelinated; neurotransmitter includes substance P; dull diffuse pain; thermal, chemical, and mechanical stimuli
C fibers
Which major pathway is the main pain pathway?
Spinothalamic
____ pathway is the spinothalamic division: Mostly A delta fibers. Provideslocation, intensity, & duration information.
Neospinothalmic:
____ pathway is the spinothalamic division: Mostly C fibers. Some of these fibers synapse with brainstem structures (Reticular Formation, Periaqueductal Gray Region, Limbic System, Hypothalamus) and also with diffuse areas of the cortex for poorly localized sense of pain.
Paleospinothalamic:
____ pathway is an alternate pathway: Mediates arousal & autonomic responses
Spinoreticular pathway.
____ pathway is an alternate pathway: Activates anti-nociceptive, descending pathways
Spinomesencephalic pathway.
____ pathway is an alternate pathway: Activates the hypothalamus
Spinohypothalamic pathway
What are the 2 types of neurons that the second order neuron in the Neospinothalmic and Paleospinothalamic tracts can be?
Nociceptive neurons or wide-dynamic range (WDR) neurons
_____ neurons receive noxious only noxious stimuli
Nociceptive-specific neurons
_____ neurons also recieve non-noxious afferent input from A-beta, A-delta, and c fibers
wide-dynamic range (WDR) neurons
_____ neurons are found in Lamina 5 and During repeated stimulation, These neurons characteristically increase their firing rate exponentially (wind-up), even with the same stimulus intensity. They have larger receptive fields than nociceptive-specific neurons; responsible for analgesia and allodynia
wide-dynamic range (WDR) neurons
____ neurons cross over in spinal cord; Found in lamina I and have discrete, somatic receptive fields; they are normally silent and respond only to high-threshold noxious stimulation, poorly encoding stimulus intensity.
Nociceptive specific neuron
____ neurons are found in the dorsal horn of the spinal cord. They respond to all somatosensory modalities. Normally only sensitive to non-noxious stimuli UNLESS the stimulus is highly noxious.
Wide-Dynamic Range (WDR) Neurons
_____ of pain enhances pain signaling
Facilitation of pain
Perception of a non-noxious stimulus as pain
Allodynia
In the __________, The A-β fibers activate an inhibitory interneuron that causes post-synaptic inhibition of the Second-order neuron for the Pain Pathway. This inhibition leads to a weaker pain signal being sent to the thalamus and somatosensory cortex. (mechanoreceptors)
Gate Control Theory of Pain
In ______, Stimulate pain in other regions of the body to inhibit pain; also called Diffuse Noxious Inhibitory Control (DNIC) or Conditioned Pain Modulation (CPM))
Pain inhibits pain
In _____, A second noxious stimulus, leads to activation of the PAG, NRM and RVM in the brainstem, which results in diffuse analgesic effect over the rest of the body.
Conditioned Pain Modulation (CPM)
What endogenous opiate in the body inhibits the first-order and second-order neurons (nociceptive specific and/or WDR neurons) in conditioned pain modulation
Enkephalin
_____ is the selective suppression of pain without effects on consciousness or other sensations.
Analgesia
What 3 parts of the brain are used in endogenous analgesia system?
PAG, NRM, and RVM
What are the 2 tracts that conveys orofacial pain?
Trigeminospinothalamic and trigeminoreticular tract
Dentin and enamel has limited space to swell in the ____ state, so results in exaggerated pain even with mild inflammation
inflammatory state
Painfully noxious _____ stimulus do not cause pain in an uninflamed healthy tooth due to thermal insulating of the enamel. But, with missing enamel and exposed dentin, a slight thermal stimuli will cause sudden and stinging pain.–It is difficult to distinguish between between noxious hot or cold stimuli.
hot/cold stimuli
Weak ______ to exposed dentin result in intense pain while in skin this would result in the sensation of light touch.
air puffs
Stimulation of _______ by any kind of stimulus results in a painful sensation.
tooth pulp
Why is there difficulty localizing tooth pain?
Large receptive fields
What part of the tooth is highly innervated with sensory afferents mostly for pain?
Pulp
dentin has limited innervation but is sensitive due to ______
dentinal tubules
____ is a mineralized, avascular tissue; Suprasensitive to extreme temperatures, particularly at the neck of the tooth (gingival recession, wear of cementum and enamel), Sensitive to hyperosmotic solutions, and NOT sensitive to KCl, bradykinin, and histamine
Dentin
Dentinal and pulp nociceptor information travels via ___ fibers and ____ fibers mainly
Aδ and C fibers
The nerve fibers in tooth pulp are ~90% ____ fibers
C-fibers.
Is dentinal pain sharp or dull pain?
Sharp
Is pulpal pain sharp or dull pain?
Dull
___ theory of dental nociception is explained by Free nerve endings in dentinal tubules are activated
Neural theory
___ theory of dental nociception is explained by Odontoblasts are excited and transduce the signal to nearby nerve cells
Odontoblast Transducer theory
___ theory of dental nociception is explained by Stimulus displaces fluid in dentinal tubules which activates mechanoreceptors in nerve endings of dentin or pulp.
Hydrodynamic theory
T/F: Not all dental pains are due to noxious temperatures (ex. water spray, puff of air, sweet substances, etc.)
true
What portion of the PDL is the most heavily innervated?
Apical portion
What fibers are used in periodontal nociception information from free nerve endings to travel?
A delta/C fibers
The _______ regulate the forces applied by the teeth in occlusion, mastication and biting. These receptors are slowly adapting, show directional sensitivity and their response varies with the force applied to the tooth.
periodontal mechanoreceptors (Ruffini endings)
