Endings around hairs located ________. Receptor ending is: _________. Adaptation is _______. Function is _______.
Hairy skin in dermis
Nerve terminal spiral wrapped around root of hair
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
Cell with no elastic structures
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: _________.
A and B fibers
A and B
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
6-12 microns in diameter
Receptors are all mechanoreceptors except a small portion of free nerve endings
A delta fibers:
1-6 microns in diameter
Receptors are free nerve endings
Less than 1.5 microns
Receptors are free nerve endings
Central terminals of afferent fibers pass to the ___________ part of the spinal cord through ______ columns in the brainstem.
Central terminal goes up to the brainstem
At each successive spinal level, fibers entering the posterior column add on _______ to those already present.
Nucleus gracilis and nucleus cuneatus are __________. Fasciculus gracilis and fasciculus cuneatus are __________.
Third order neurons go from _____ to __________.
Thalamus to Cortex
Information from head goes to:
Then they get relayed as sensory information to S1
Information from body goes to:
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.
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 _________.
Forming tactile memories
In somatotropic mapping, information from face takes a significant portion of the _______ part of the somatosensory cortex.
In somatotropic mapping, the body input can be found in the more _______ aspect of the somatosensory cortex.
Objective signs of nociception include:
Absence of pain
Absence of all sensation
A and C fibers are responsive to:
Mechanical on skin
Heat >45 degrees C
Cold < 20 degrees C
Transmitters of nociception are:
As you increase the stimulus temperature, you ______ the frequency of action potentials.
To protect from touching the site of injury
Efferent function of nociceptors:
Pathways that cause vasoconstriction
Low threshold input from:
Wide dynamic from:
Mechanoreceptors and nociceptors
High threshold from:
Location, intensity, and quality of pain
Emotional reaction to pain
STT neurons can become sensitized after injury or inflammation. This is the physiological correlate of:
Spinoreticular tract function:
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