Endings around hairs located ________. Receptor ending is: _________. Adaptation is _______. Function is _______.
Hairy skin in dermis
Nerve terminal spiral wrapped around root of hair
Rapid
Hair movement
Merkel endings are located in __________. There are ____ Merkel cells for every 1 nerve terminal. Receptor endings are found in cells with ________. _________ adapting. Functions are _________.
All skins - in deep epidermis about basal membrane
5-10
Cell with no elastic structures
Slowly
Light pressure, not much known
Free nerve endings are located in ________. Receptor endings for unmylinated nerves end in ________ fibers. Also endings in ____ fibers. _______ fibers are rapidly adapting. _____ fibers are slowly adapting. Functions are: _________.
Epidermis
A and B fibers
C
A and B
C
Thermal and pain, some are mechanical
Receptive Field (RF)
Every mechanoreceptor has a particular area in the periphery where adequate mechanical stimulation produces the response of a single mechanoreceptor.
A beta fibers
Most common
Myelinated
6-12 microns in diameter
30-70 m/s
Receptors are all mechanoreceptors except a small portion of free nerve endings
A delta fibers:
Thin myelinated
1-6 microns in diameter
5-30m/s
Receptors are free nerve endings
C fibers
Unmyelinated
Less than 1.5 microns
.5-2 m/s
Receptors are free nerve endings
Central terminals of afferent fibers pass to the ___________ part of the spinal cord through ______ columns in the brainstem.
Ipsilateral
Dorsal
Fasciculus gracilis
Dorsal column
Central terminal goes up to the brainstem
Fasciculus cuneatus
Cervical segments
At each successive spinal level, fibers entering the posterior column add on _______ to those already present.
Laterally
Nucleus gracilis and nucleus cuneatus are __________. Fasciculus gracilis and fasciculus cuneatus are __________.
Contralateral
Ipsilateral
Third order neurons go from _____ to __________.
Thalamus to Cortex
Information from head goes to:
VPM
Then they get relayed as sensory information to S1
Information from body goes to:
VPL
Then gets relayed as sensory information to S1
VPL is called relay nucleus because it gets input from ____ and _______. It also sends output to the cerebral cortex.
Nucleus Gracilus
Nucleus Cuneatus
VPM is important for __________.
Pain transmission for head, neck, and mouth.
3rd order neurons in VPL raise their axons to:
Primary Somatosensory Area (S1) of cerebral cortex
Input to _______ comes from S1 and may play a role in _________.
S2
Forming tactile memories
In somatotropic mapping, information from face takes a significant portion of the _______ part of the somatosensory cortex.
Lateral
In somatotropic mapping, the body input can be found in the more _______ aspect of the somatosensory cortex.
Medial
Objective signs of nociception include:
Increased BP
Increased Respiration
Electrophysiology
Analgesia
Absence of pain
Anasthesia
Absence of all sensation
A and C fibers are responsive to:
Mechanical on skin
Heat >45 degrees C
Cold < 20 degrees C
Algesic chemicals
Transmitters of nociception are:
Substance P
Glutamate
As you increase the stimulus temperature, you ______ the frequency of action potentials.
Increase
Hyperalgesia function
To protect from touching the site of injury
Efferent function of nociceptors:
Pathways that cause vasoconstriction
Low threshold input from:
Mechanoreceptors only
Wide dynamic from:
Mechanoreceptors and nociceptors
High threshold from:
Nociceptors only
Lateral STT
Location, intensity, and quality of pain
Medial STT
Emotional reaction to pain
STT neurons can become sensitized after injury or inflammation. This is the physiological correlate of:
hyperalgesia.
Spinoreticular tract function:
arousal
Spinohypothalamic tract function:
Autonomic reaction to pain (HR, BP, Respiration)
Spinomesencephalic tract function:
To periacqueducatl gray (PAG).
Inhibiting/modulating pain. --> decreases activity of descending neurons