Pain Flashcards
unpleasant sensory and emotional experience associated with actual or potential tissue damage. provokes withdrawal response to prevent further injury
pain
immediately after the injury has occurred when tissue damage is involved. less than 6 months
acute pain
lasts longer than 6 months. persistent pain. continues after noxious stimuli is no longer there
chronic pain
perceived in an area that has little relation to the existing pathology
referred pain
irritation of nerves that cause pain radiating down the nerve path
radiating pain
pain associated with a sclerotome (segment of bone innervated by a spinal segment)
deep somatic pain
activated by light touch
Meissner’s corpuscles
respond to deep pressure
Pacinian corpuscles
respond to deep pressure, but more slowly than pacinian, and also are activated by hair follicle deflection
Merkel’s corpuscles
sensitive to touch, tension, and heat
Ruffini corpuscles
thermoreceptors that react to a decrease in temperature and light touch
Krause’s end bulbs
free nerve endings. Sensitive to extreme mechanical, thermal, or chemical energy. Respond to noxious stimuli
Nociceptors
transmit from periphery sensory receptors to the dorsal horn.
First order neurons
3 types of 1st order neurons
A-Delta
A-Beta
C-fibers
carry sensory info from spinal cord to the brain
second order neurons
sends info to the sensory cortex in the brain to transmit pain signals
third order neurons
Largest motor nerves. Myelinated. N: skeletal mm fibers
A fibers
responsible for muscular contractions that generates the force of the muscle
extrafusal fibers
responsible for sensing changes in mm fiber length and rate of change in mm length. Inside mm itself
intrafusal fibers
specialized sensory receptor that senses tension in the mm.
Golgi tendon organs GTO
large, myelinated efferent nerve. N: extrafusal mm fibers
ALPHA motor
smaller, myelinated efferent nerve. N: intrafusal mm fibers
GAMMA motor
Very fast, myelinated afferent nerve. Divided into IA and IB fibers
A ALPHA
carries info regarding mm change in length and the rate of that change
IA
carries info regarding tension in the tendon, N: GTO
IB
medium, myelinated afferent nerve. Fast touch and proprioception. Gate Control Theory
A BETA
small, myelinated afferent nerves. 20% of pain transmitting fibers. Acute pain
A DELTA
Slow, unmyelinated afferent nerve. Skin, mm, viscera. 80% of pain transmitting fibers. Chronic pain
C fibers
causes depolarization of the post synaptic membrane through a neurotransmitter
excitatory stimulus
causes hyperpoarization at the synapse
inhibitory stimulus
neuron which transmits pain signals, cell body is in the dorsal root ganglia. causes release of substance p when stimulated
nociception
initiates afferent impulses towards the spinal cord. transmitter between neurons at the dorsal horn.
substance p
severity of pain sensation is determined by the balance of excitatory and inhibitory inputs to the T cells in the spinal cord. Stimulation blocks pain impulses
Gate Control Theory
A BETA stimulation blocks A DELTA and C fiber impulses
Gate Control Theory
chemical mediator that excites pain transmitting neurons in the dorsal horn of spinal cord
Substance P
Endorphins help regulate pain in times of high emotional stress.
Endorphin Theory
