Ch 6: Pain & Temperature Flashcards
what are the 3 general types of sensory receptors?
1- exteroceptive receptors
2-proprioceptive receptors
3- interoceptive receptors
what do exteroceptive receptors respond to?
respond to stimuli from the external environment
including visual, auditory and tactile stimuli
what do proprioceptive captors do?
receive information about the relative positions of the body segments and of the body in space
what to interoceptive receptors detect?
internal events such as changes in BP
where does the somatic system primarily receive information from?
exteroceptive and proprioceptive receptors
what are the 4 major subclasses of somatic sensation?
1- pain sensation
2-thermal sensation
3-position sense
4-touch-pressure sensation
pain sensation results from:
noxious stimulation of the body surface
thermal sensation consists of:
the separate senses of cold and warmth and occurs with exposure to temperatures colder or warmed than the body surface
position sense results from:
mechanical changes in the muscles and joints, but it includes the sensations of static limb position and limb movement (kinesthesia)
touch-pressure sensation occurs with:
mechanical stimulation of the body surface
the anterolateral system mediates the:
sensations of pain, itching, temperature and simple touch
itching sensation is related to ____?
pain
simple touch is a form of ?
touch pressure sensation that includes a feeling of light contact with the skin associated with light pressure and crude sense of tactile localization.
the anterolateral system originates from?
neurons located in several layers of the dorsal horn of the SC
most of the axons projecting from these neurons cross the midline through the ventral white commissure and ascend the SC, to give rise to a diffuse bundle of fibers projecting through the anterior and lateral funiculi
the cells of anterolateral system origin are activated by:
small-diameter, lightly myelinated and unmyelinated dorsal root afferents
including Adelta (III) and C (IV) fibers as well as larger myelinated cutaneous afferents
the anterolateral system includes the:
spinothalamic tracts and the spinoreticular tracts (which do not reach the thalamus and thus can’t be termed spinothalamic)
dorsal roots convey __________ to the SC
essentially all sensation from receptors below the face
what is a dermatome?
area of skin supplied by one dorsal root
cutaneous branches of each peripheral nerve carries fibers from more than one spinal nerve, and the skin territory of each of these peripheral nerves covers portions of several dermatomes
a few sensory fibers have been discovered in the ventral roots. many of these ventral root afferents respond to ____?
painful stimuli from superficial or deep tissues
the cell bodies of the dorsal root fibers are located _____?
in the spinal or dorsal root, ganglia
there are no synapses in a dorsal root ganglion
dorsal root fibers enter the spinal cord through the ___?
dorsal root entry zone- a region of the dorsolateral sulcus
the largest and most heavily myelinated fibers (Aalpha and Abeta) generally occupy the most ____ position in the dorsal root entry
medial
small myelinated and unmyelinated fibers (Adelta and C) occupy the most ____ position of the dorsal root entry.
lateral
what makes up a spinal nerve?
the convergence of dorsal and ventral roots
what makes up a peripheral nerve?
peripheral to the convergence of a spinal nerve, a mixture of sensory and motor fibers from the individual spinal nerves separates into bundles or fascicles that join those of adjacent spinal nerves
what are the peripheral receptors for pain?
the naked terminals of small (Adelta and C) nerve fibers
many of these may be specialized chemoreceptors that are excited by tissue substances released in response to noxious and inflammatory stimuli.
many substances have been implicated, including histamine, bradykinin, serotonin, acetylcholine, substance P high concentrations of K, and substances involved in the arachidonic acid cascade
the concentration of hydrogen ion in these substances is critical in the activation of pain receptors
the cell bodies of Adelta and C axons mediating noxious stimuli are in the ____ and enter the SC through the ____ part of the dorsal root zone and immediately divide into _____ and ______ that run longitudinally in the _________?
dorsal root ganglia
enter the SC through the lateral part
divide into short ascending and descending branches
posterolateral fasciculus
these fibers leave to connect synaptically with neurons in the dorsal horn. At their connections with these neurons, Adealtha and C fibers release glutamate and substance P, etc.
Interneurons in laminae I-IV project to neurons in laminae V and there make synaptic connection on the cells of origin of the anterolateral system (including spinothalamic and spinoreticular tracts/projectoions. Neurons in lamina I give rise to fibers that contribute directly to spinothalamic tracts
the posterolateral faciculus is also known as:
Lissauer’s tract
what is the leminscal system?
one of the major sensory pathways ascending the spinal cord and into consciousness; conducts sensitive impulses relating to touch, pressure, vibration and joint proprioception via the dorsal funiculus and the medial lemniscus and thalamus before reaching the cortex.
what is the limbic system?
a group of brain structures (including the hippocampus, gyrus fornicatus, and amygdala) common to all mammals; it is associated with olfaction, autonomic functions, and certain aspects of emotion and behavior.
the axons of spinothalamic tract cells in laminae I-V cross ___________ and then course ________?
cross anterior to the central canal in the ventral white commissure
and then course rostrally in the anterolateral funiculus
the spinothalamic and spinoreticular tracts ascend through the _____ and supply ____?
through the SC and brain stem
supply inputs to:
- other SC segments
- the reticular formation
- superior colliculus
- several thalamic nuclei (including the intralaminar nuclei and then ventral posterolateral nucleus (VPL)
what is the VPL?
ventral posterolateral nucleus