PAT 201 - WEEK 4 Questions with Verified
Correct Answers
Pain
An unpleasant sensory and emotional experience associated with actual or potential tissue
damage
- Protective and complex phenomenon made up of dynamic interactions among physical,
cognitive, spiritual, emotional, and environmental factors
What is Gate Control Theory?
- Explains complexities of the pain phenomenon
- Pain is a modulated by a "gate" in the cells of the substantia gelatinosa in the spinal cord
Gate Control Theory Process (Nociceptive Transmissions)
- Large myelinated A-delta fibers and small unmyelinated C fibers respond to broad range of
painful stimuli (mechanical, thermal, chemical) NOCICEPTIVE TRANSMISSIONS "open"
the gate
- Stimuli from non-nociceptive transmissions (touch and larger A-beta fibers), "close" or
partially close the gate
Systems/Pathways Necessary for Pain
- Afferent Pathways
- Interpretive Pathways
- Efferent Pathways
Afferent Pathways
,Begin in the Peripheral Nervous System (PNS) --> travel to spinal gate in dorsal horn -->
ascend to higher centers in the CNS
Interpretive Centers
Located in the brainstem, midbrain, diencephalon (thalamus, epithalamus, hypothalamus) and
cerebral cortex
Efferent Pathways
Descend from the CNS to the dorsal horn of the spinal cord
Processing of Pain: 4 Phases of Nociception
1. Transduction
2. Transmission
3. Perception
4. Modulation
TRANSDUCTION
Begins when tissue is damaged by exposure to chemical, mechanical, or thermal noxious
stimuli and is converted to electrophysiologic activity
TRANSMISSION
Conduction of pain impulses along the A and C fibers into the dorsal horn of the spinal cord
and eventually to the reticular formation, hypothalamus, thalamus, and limbic system
TRANSMISSION: Primary-Order Neurons
Nociceptors
Are stimulated by severe mechanical deformation and/or temperature extremes
- Myelinated Alpha-delta Fibers
, - Unmyelinated C Polymodal Fibers
- Alpha-beta Fibers
Myelinated Alpha-Delta Fibers
Transmission is fast and causes reflex withdrawal of affected body part from stimulus before
pain sensation is perceived
- Sensations are sharp, well-localized, and "fast"
Unmyelinated C Polymodal Fibers
Most numerous
Stimulated by mechanical, thermal, and chemical nociceptors
- Transmission is slower and conveys dull, aching, or burning sensations
Alpha-Beta Fibers
Large myelinated fibers that transmit touch and vibration sensations
TRANSMISSION: Secondary-Order Neurons
Are interneurons in the dorsal horn of the spinal column
- Projection cells
- Excitatory or inhibitory interneurons
- Cross over the cord and ascend or descend
TRANSMISSION: Third-Order Neurons
Are afferent neurons in the spinothalamic tract
- Carry info to reticular formation, hypothalamus, thalamus, and limbic system to interpret
pain location and intensity
PERCEPTION
Correct Answers
Pain
An unpleasant sensory and emotional experience associated with actual or potential tissue
damage
- Protective and complex phenomenon made up of dynamic interactions among physical,
cognitive, spiritual, emotional, and environmental factors
What is Gate Control Theory?
- Explains complexities of the pain phenomenon
- Pain is a modulated by a "gate" in the cells of the substantia gelatinosa in the spinal cord
Gate Control Theory Process (Nociceptive Transmissions)
- Large myelinated A-delta fibers and small unmyelinated C fibers respond to broad range of
painful stimuli (mechanical, thermal, chemical) NOCICEPTIVE TRANSMISSIONS "open"
the gate
- Stimuli from non-nociceptive transmissions (touch and larger A-beta fibers), "close" or
partially close the gate
Systems/Pathways Necessary for Pain
- Afferent Pathways
- Interpretive Pathways
- Efferent Pathways
Afferent Pathways
,Begin in the Peripheral Nervous System (PNS) --> travel to spinal gate in dorsal horn -->
ascend to higher centers in the CNS
Interpretive Centers
Located in the brainstem, midbrain, diencephalon (thalamus, epithalamus, hypothalamus) and
cerebral cortex
Efferent Pathways
Descend from the CNS to the dorsal horn of the spinal cord
Processing of Pain: 4 Phases of Nociception
1. Transduction
2. Transmission
3. Perception
4. Modulation
TRANSDUCTION
Begins when tissue is damaged by exposure to chemical, mechanical, or thermal noxious
stimuli and is converted to electrophysiologic activity
TRANSMISSION
Conduction of pain impulses along the A and C fibers into the dorsal horn of the spinal cord
and eventually to the reticular formation, hypothalamus, thalamus, and limbic system
TRANSMISSION: Primary-Order Neurons
Nociceptors
Are stimulated by severe mechanical deformation and/or temperature extremes
- Myelinated Alpha-delta Fibers
, - Unmyelinated C Polymodal Fibers
- Alpha-beta Fibers
Myelinated Alpha-Delta Fibers
Transmission is fast and causes reflex withdrawal of affected body part from stimulus before
pain sensation is perceived
- Sensations are sharp, well-localized, and "fast"
Unmyelinated C Polymodal Fibers
Most numerous
Stimulated by mechanical, thermal, and chemical nociceptors
- Transmission is slower and conveys dull, aching, or burning sensations
Alpha-Beta Fibers
Large myelinated fibers that transmit touch and vibration sensations
TRANSMISSION: Secondary-Order Neurons
Are interneurons in the dorsal horn of the spinal column
- Projection cells
- Excitatory or inhibitory interneurons
- Cross over the cord and ascend or descend
TRANSMISSION: Third-Order Neurons
Are afferent neurons in the spinothalamic tract
- Carry info to reticular formation, hypothalamus, thalamus, and limbic system to interpret
pain location and intensity
PERCEPTION
