Podcast
Questions and Answers
Which type of nerve fiber transmits sharp, localized pain?
Which type of nerve fiber transmits sharp, localized pain?
The transmission of pain signals from the spinal cord to the brain stem and thalamus occurs in the second segment of pain transmission.
The transmission of pain signals from the spinal cord to the brain stem and thalamus occurs in the second segment of pain transmission.
True (A)
What is the process of amplifying the pain signal called?
What is the process of amplifying the pain signal called?
Modulation
The body's natural pain management system involves the release of ______ such as endorphins, serotonin, and norepinephrine.
The body's natural pain management system involves the release of ______ such as endorphins, serotonin, and norepinephrine.
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Match the following pain transmission segments with their corresponding locations:
Match the following pain transmission segments with their corresponding locations:
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Which of the following is NOT a factor that influences the extent of pain perceived?
Which of the following is NOT a factor that influences the extent of pain perceived?
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Pain can be measured objectively like other vital signs such as heart rate or blood pressure.
Pain can be measured objectively like other vital signs such as heart rate or blood pressure.
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According to Margo McCaferry, how is pain defined?
According to Margo McCaferry, how is pain defined?
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Pain is an unpleasant sensory and ___________ experience associated with actual or potential tissue damage.
Pain is an unpleasant sensory and ___________ experience associated with actual or potential tissue damage.
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Match each statement with the correct concept:
Match each statement with the correct concept:
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Which of the following is NOT a type of stimulus that activates nociceptors?
Which of the following is NOT a type of stimulus that activates nociceptors?
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Nociceptors are found in every tissue of the body, including the brain.
Nociceptors are found in every tissue of the body, including the brain.
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What are the two types of nerve fibers that nociceptors are classified into?
What are the two types of nerve fibers that nociceptors are classified into?
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The physiologic process related to pain perception is described as ___________.
The physiologic process related to pain perception is described as ___________.
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Match the following stages of nociception to their descriptions:
Match the following stages of nociception to their descriptions:
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What is the initial step in the physiology of pain?
What is the initial step in the physiology of pain?
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Substance P is primarily involved in the modulation of pain signals.
Substance P is primarily involved in the modulation of pain signals.
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What specific type of nerve endings respond to noxious stimuli during transduction?
What specific type of nerve endings respond to noxious stimuli during transduction?
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The exchange of _______ and _______ ions at the cell membrane leads to action potentials and pain impulse generation.
The exchange of _______ and _______ ions at the cell membrane leads to action potentials and pain impulse generation.
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During the transmission phase, pain impulses travel from the peripheral nerve fibers to which area?
During the transmission phase, pain impulses travel from the peripheral nerve fibers to which area?
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Pain medications can only impact the transmission phase of pain physiology.
Pain medications can only impact the transmission phase of pain physiology.
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Which of the following is NOT a chemical mediator involved in the sensitization of nociceptors during transduction?
Which of the following is NOT a chemical mediator involved in the sensitization of nociceptors during transduction?
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Match the following pain physiology phases with the correct description:
Match the following pain physiology phases with the correct description:
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What is referred pain?
What is referred pain?
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The gate control theory suggests that pain signals are transmitted to the brain without modulation.
The gate control theory suggests that pain signals are transmitted to the brain without modulation.
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Where does the basic pain sensation occur in the brain?
Where does the basic pain sensation occur in the brain?
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Visceral pain arises from _________ or hollow viscera.
Visceral pain arises from _________ or hollow viscera.
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Match the following structures with their role in the pain sensation process:
Match the following structures with their role in the pain sensation process:
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Which of the following methods is a clinical application of pain control?
Which of the following methods is a clinical application of pain control?
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Transcutaneous electrical nerve stimulation (TENS) uses electrical impulses to reduce pain.
Transcutaneous electrical nerve stimulation (TENS) uses electrical impulses to reduce pain.
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Name a common initial response of the body to pain.
Name a common initial response of the body to pain.
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The modulation of pain signals occurs in the _________.
The modulation of pain signals occurs in the _________.
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Which of the following is NOT a response to pain?
Which of the following is NOT a response to pain?
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Pain modulation can be influenced by psychological factors.
Pain modulation can be influenced by psychological factors.
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What types of nerve fibers have an inhibitory effect on pain perception?
What types of nerve fibers have an inhibitory effect on pain perception?
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The phenomenon where pain is felt in the left shoulder due to heart issues is called ________ pain.
The phenomenon where pain is felt in the left shoulder due to heart issues is called ________ pain.
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Study Notes
Learning Outcomes
- Students should be able to define pain
- Students should be able to explain the physiology of pain
- Students should be able to describe referred pain
- Students should be able to explain the gate control theory
- Students should be able to describe responses to pain
Introduction
- The ability to perceive and react to threats is a protective homeostatic process
- Pain perception is complex activities in the central nervous system
- The character and intensity of pain perceived are shaped by these activities
- The level of pain perceived depends upon:
- Interaction between the body's analgesia system and nervous system's transmission
- How the mind interprets the stimuli
- Individual perception
Definition of Pain
- Pain is an unpleasant and highly personal experience
- Pain is an unpleasant sensory and emotional experience associated with actual or potential tissue damage
- Pain is whatever the experiencing person says it is
Physiology of Pain
- Nociceptors are sensory receptors for pain
- They are free nerve endings in every tissue except the brain
- Nociceptors respond to painful stimuli (noxious stimuli) like:
- Electrical
- Mechanical
- Thermal
- Chemical
- Nerve cell bodies are located in the dorsal root ganglia
- Nociceptors are classified into two types of fibers:
- C fibers: conduct nerve impulses slowly; respond to thermal, mechanical, and chemical stimuli
- A-delta fibers: conduct nerve impulses faster
Nociception
- When nociceptors are activated, the signals need transduction and transmission to the spine and brain
- The signals are modified before they are understood as pain
- The process of pain perception is called nociception
Physiologic Processes in Nociception
- Transduction: release of substances stimulating the nociceptors
- Transmission: movement of pain sensation to the spinal cord
- Modulation: brain sending signals down the spinal cord; the process of the brain
- Perception: pain is recognized
Pain Reception and Response
- The stimulus received is sent to the CNS
- Action can occur by a "loop" involving only the sensory neuron, integrator neuron, and effector organ
- The brain is informed and can suppress pain response by secreting endogenous opioids
Physiology of Pain - Transduction
- Begins when free nerve endings (nociceptors) of C fibers and A-delta fibers respond to noxious stimuli
- Noxious stimuli trigger the release of biochemical mediators that sensitize nociceptors
Example of Chemical Mediators
- Substance P
- Prostaglandings
- Bradykinin
- Serotonin
- Histamine
Physiology of Pain - Transduction (Continued)
- For pain impulses to be generated, there is exchange of sodium and potassium ions
- De-polarisation and re-polarisation occur at the cell membranes
- This creates an action potential and generates a pain impulse
Pain Medications
- Pain medications can work during this phase by blocking production of prostaglandin or by decreasing the movement of ions across the cell membrane
Physiology of Pain - Transmission
- Includes three segments:
- First segment: pain impulses move from peripheral nerve fibers to the spinal cord, Substance P serves as the neurotransmitter and moves impulses across the synapse from the primary afferent neuron to the secondary neuron in the dorsal horn of the spinal cord
- Second segment: transmission of signals from the spinal cord to the brain stem and thalamus via spinothalamic tracts
- Third segment: transmission of signals between the thalamus and somatic sensory cortex, and to the limbic system (emotional center)
Two Types of Nociceptor Fibers
- Unmyelinated C fibers: transmit dull, aching pain
- Thin A-delta fibers: transmit sharp, localized pain
Physiology of Pain - Modulation
- It is the process of amplifying the pain
- Takes place in the dorsal horn of the spinal cord
- Often described as a descending system
- Occurs when neurons in the thalamus and brain stem send signals back down to the dorsal horn of the spinal cord
- The body has built-in chemical mechanisms (endogenous opioids) to manage pain
Descending Fibers
- Release substances such as endogenous opioids, serotonin, and norepinephrine
- These substances can inhibit the ascending noxious impulses in the dorsal horn.
- Excitatory amino acids (e.g., glutamate, N-methyl-D-aspartate/NMDA) can facilitate pain signals.
Physiology of Pain - Perception
- The final process when pain is felt
- The basic pain sensation occurs in the thalamus and continues to the limbic system (emotional center) and cerebral cortex
- The psychological context and meaning of pain, based on past experiences and future hopes, shapes the behavioral response
Responses to Pain
- The body's response is complex, with both physiological and psychosocial aspects
- Initially, the sympathetic nervous system responds, resulting in the fight-or-flight response (increased pulse and blood pressure)
- People may hold their breath, have shallow breathing, or exhibit reflexive movements as they withdraw from the painful stimulus
- Over minutes or hours, pulse and blood pressure generally return to baseline even while pain persists.
- Unrelieved pain can have harmful effects on well-being, sleep, appetite and quality of life.
Clinical Application: Pain Control Methods
- Opioids & Alpha2 agonists: Used for pain management
- Local anesthetics: Used to numb or block pain signals
- Anti-inflammatory drugs: Used to reduce inflammation contributing to pain
- Epidural analgesia: Injection of medication into the epidural space to block pain transmission
- Patient Control Analgesia (PCA): Allows patient to self-administer pain medication through a pump.
Referred Pain
- Visceral pain is often felt in an area distant from the source of the pain. The nerves serving the organ and the skin area may converge on the same neurons in the spinal cord. Thus, pain from the organ is perceived in a location distant from the organ itself
- The pain experienced is the result of the overlap of both pain fibers from the stimulated organ and the body's sensory nerves
Gate Control Theory
- Melzack and Wall's 1965 theory.
- Sensory input from peripheral fibers modulates before being transmitted to the brain.
- Gates at afferent synapses in the spinal cord and brain control pain signal transmission
- When gates are open, pain signals ascend via the spinothalamic tract
- Pain can be moderated or reduced when the gates are closed
Gate Control Theory & Clinical Application
- Peripherally, large-diameter A-delta nerve fibers (touch, temperature) have an inhibitory effect.
- Higher brain centers (affect and motivation) modify and influence gate opening/closing.
- Clinically, nurses use this model for therapies like topical, massage, or addressing mood and emotion
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Description
This quiz explores the complex nature of pain perception, including its definitions, physiology, and theories. Students will learn about referred pain, the gate control theory, and individual responses to pain. Understanding these concepts is critical for those studying human physiology and psychology.
