Physiology of Pain Flashcards
_____ are pain receptors, which detect
physical or chemical damage occurring in
the tissues.
Nociceptors
Information from these sensory receptors is
transduced from a ____ or ____
stimuli into an electrical impulse in the
neuron, which is then carried to the CNS
physical or chemical
There are several different types of sensory
receptors in the tissues:
○ Mechanoreceptors
○ Thermoreceptors
○ Nociceptors
○ Electromagnetic receptors
○ Chemoreceptors
Incoming sensory information is processed
in the _____ of the brain.
somatosensory cortex
Receptors that are specific for pain are ____
Nerve Endings in the skin and other tissues.
Free
There are three main types of stimuli that can excite pain receptors when tissue damage is occurring
○ Mechanical: Pressure or crushing
○ Thermal: Burning or freezing
○ Chemical: Bradykinin, serotonin, histamine,
potassium ions, prostaglandins, etc
Free Nerve Endings use two separate fibers for transmitting pain signals to the CNS
● Fast, sharp pain is transmitted from the peripheral tissue to the spinal cord via small type A delta fibers.
● Slower, aching pain is transmitted to
the spinal cord via type C fibers.
____ stimulated pain is generally transmitted via the slower type C Fibers
Chemical
After synapsing and decussating via
the anterior white commissure, the
signal is carried up the ____ of the spinal cord.
Spinothalamic Tract
Along the way to the brain, some fibers synapse on cells in the _____ of the brainstem
Reticular Formation
Most fibers make it to the Thalamus, where
the information is then relayed to the
_____ .
Somatosensory cortex
The Somatosensory Cortex likely plays an especially important role of interpreting the pain ____
quality
Three very important neurotransmitters (which are endogenous opiates) play a role in suppressing incoming pain signals:
○ Endorphin
○ Enkephalin
○ Dynorphin
Studies have revealed that when incoming painful stimuli reaches the brain, efferent fibers may fire releasing these three neurotransmitters, which stimulates a chain of events result in pain relief. This natural pain relief chain of events is what we refer to as the CNS _____
Analgesia System
The analgesia system consists of three major components
○ Periaqueductal Gray
○ Raphe Magnus Nucleus
○ Substantia Gelatinosa
When ______ is released in the Substantia Gelatinosa, the endogenous opiate binds to opiate receptors, of which there are three types (μ, κ, and δ).
enkephalin
Pain felt in more distant sites that have similar innervation. (well localized)
Referred pain
Explain viseral pain
○ When hollow organs contract forcefully or are distended.
○ When solid organs like the liver distend and stretch their capsule.
○ Difficult to localize.
○ Can be gnawing, burning, cramping, or aching.
