Nociception Flashcards
Define nociception
Detection of a noxious stimuli by stimulating nociceptors
What are the 3 kinds of stimulus nociceptors respond to?
- Mechanical
- Thermal
- Chemical
Nociceptors have _______ nerve endings and ______ distribution to all parts of the body.
Free nerve endings
Wide distribution
What are the 2 main nociceptor fiber types?
AD Fibers- (alpha-delta fibers)
C Fibers
Which fibers are associated with sharp, pricking pain?
AD Fibers
Which fibers are fast-conducting and mylinated?
AD Fibers
Which fibers are associated with burning or throbbing pain?
C Fibers
Which fibers are unmyelinated and slow-conducting?
C Fibers
Which fibers detect superficial and deep pain?
BOTH fibers detect BOTH superficial and deep pain
Which reflex uses nociceptor fibers for the sensory part of the reflex?
Withdrawal reflex
Is pain reaction a voluntary or involuntary behavior?
It is VOLUNTARY behavior
Trauma or inflammation causes ______ pain.
ACUTE
What is Hypoalgesia?
Decreased perception of pain
What is Analgesia?
Complete absence of perception of pain
What is Anesthesia?
Complete absence of all sensory perception
The ARAS is important in nociception because it is the link between sensory stimulation and ________.
Arousal
Noxious stimuli ______ alertness and autonomic functions (heart and respiratory rate)
increases
T or F: Increased heart and respiratory rates imply cortical involvement.
NO!!
What are the Ascending Nociceptive Pathways?
Spinocervicothalamic tract
Spinoreticular tract
Which path is responsible for transmitting superficial pain and tactile sensations? (Pinching)
Spinocervicothalamic tract
Which path is responsible for transmitting deep pain signals?
Spinoreticular tract
What is the primary conscious pain pathway in carnivores?
Spinocervicothalamic tract
Location of the stimulus can be precisely determined by the animal via the _________ tract.
Spinocervicothalamic tract
The spinocervicothalamic tract has a high degree of _______.
Somatotopy
Which tract transmits deep pain and visceral sensation?
Spinoreticular tract
Which pain pathway is more vulnerable to compressive injury?
Spinocervicothalamic tract
Dull, aching, and throbbing pain is what type of pain?
Visceral
Why is there a negative emotional reaction to pain?
Because the pain pathways are connected to the limbic system
An individual with no aversion to pain might have a damaged _______ system.
Limbic system damaged.
What parts of the body are responsible for modulating pain perception?
Periphery
Spinal Cord
Brainstem
What substances lower the threshold of nociceptors making them easier to stimulate?
Inflammatory mediators released by injured tissue such as prostaglandins and leukotrienes
What substances DIRECTLY stimulate pain receptors?
Bradykinin
Serotonin
K+
What is Substance P?
neurotransmitter that dilates blood vessels and degranulates mast cells
Substance P ________ sensitization of nociceptors.
Increases
What is hyperalgesia?
When noxious stimuli produces greater than normal nociceptor activity.
Substance P contributes to hyperalgesia
What is allodynia?
When non-noxious stimuli activates nociceptors
Substance P contributes to allodynia
Wide Dynamic Range neurons respond to what kind of stimuli?
Noxious and non-noxious stimuli
“Referred Pain” of visceral organs is associate with what type of neurons?
Wide Dynamic Range neurons
What is “Wind-Up”?
Spinal fasciculation of pain - rapid firing of nociceptor afferents (AD and C fibers). This means CHRONIC PAIN
NMDA receptors are activated with?
Chronic pain and windup
What ions do NMDA receptors allow into the cell?
Calcium and Sodium
Why are patients more painful over time if chronic pain is left untreated?
Because chronic pain produces long term changes that lead to greater sensitivity
Does anesthesia prevent windup?
NO
How is windup/chronic pain prevented?
Nerve blocks and aggressive pain management
How is windup treated?
NMDA receptor inhibitors and acupuncture
What is Gate Control Theory?
Non-noxious tactile stimulation
Can help reduce perception of pain
Descending modulatory pathways lead to release of which neurotransmitters?
Enkephalin, Endorphin, Dynorphin, Seratonin, NE
Which neurotransmitter have anti-nociceptive (anti-pain) properties?
Enkephalin, endorphins, dynorphins, seratonin, NE
What are ways to control pain?
Modulate or prevent transduction at the
nociceptor- NSAIDS
Interfere with conduction to the CNS- nerve blocks, anesthesia
Recruit the neuroanatomic substrate of the gate
control theory- water therapy, massage, acupuncture
Inhibit spinal cord sensitization- NMDA receptor inhibitor
Augment descending modulatory mechanisms- opioids and a-adrenergics
Reduce perception of pain- sedation
What modulates or prevents transduction at the
nociceptor?
NSAIDS
What will interfere with conduction to the CNS?
Nerve blocks and anesthesia
What will recruit the neuroanatomic substrate of the gate control theory?
Water therapy, massage, acupuncture
What will Inhibit spinal cord sensitization?
NMDA receptor inhibitors
What will augment descending modulatory mechanisms?
Opioids and a-adrenergics
What will reduce perception of pain?
Sedation
What stimuli provokes itch?
Pressure
Temperature
Electricity
Chemicals- histamine
Why does Neuropathic pain arise?
As a result of injury to the nervous system
What 4 things can cause neuropathic pain?
- Trauma
- Vascular injury
- Endocrinopathy- Diabetes mellitus
- Infection
Hyperalgesia and allodynia are associated with what type of pain?
Neuropathic pain
What is dysesthesia?
A tingling sensation associated with neuropathic pain
