Sensory Physiology Flashcards
Pain receptors in the skin are typically classified as which of the following?
A. Encapsulated nerve endings
B. Single class of morphologically specialized receptors
C. The same type of receptor that detects position sense
D. Free nerve endings
Free nerve endings
Which of the following is best described as an elongated, encapsulated receptor found in the dermal pegs of glaborous skin that is especially abundant on lips and fingertips?
A. Merkel disc
B. Free nerve endings
C. Meissner Corpuscle
D. Ruffini endings
Meissner Corpuscle
Which of the following is the encapsulated receptor found deep in the skin throught the body as well as in fascial layers, where it detects indentation of the skin (pressure) and movement across the surface (vibration)?
A. Pacini corpuscle
B. Meissner’s Corpuscle
C. Free Nerve Endings
D. Ruffini Endings
Pacini corpuscle
Interneurons that utilize the neurotransmitter encephalin to inhibit afferent pain signals are most likely to be found in which region of the CNS?
A. Dorsal horn of the spinal cord
B. Postcentral gyrus
C. Alpha-delta fibers
D. C fibers
E. Ventral horn of the spinal cord
Dorsal horn of the spinal cord
Neurons originating in which area release serotonin as their neurotransmitter?
A. Periaqueductal gray area
B. Interneurons of the spinal cord
C. Periventricular area
D. Raphe Nucleus
Raphe Nucleus
You cut your finger with a pocketknife and immediately apply pressure to the damaged area of your hand with your other hand. Inhibition of pain signals by tactile stimulation of the skin is mediated by which type of afferent neurons from mechanoreceptors?
A. A-alpha
B. A-beta
C. A-delta
D. C fibers
A-beta
Which of the following brain areas contributes most directly to the descending pain suppression system?
A. Superior Olivary complex
B. Locus Ceruleus
C. Periaqueductal gray area
D. Amygdala
E. Insular Cortex
Periaqueductal gray area
The terminals of nociceptive afferents release which one of the following transmitters?
A. Substance P
B. GABA
C. Enkephalins
D. Serotonin
E. Acetylcholine
Substance P
A neuroscientist noticed attenuation of pain sensation in an experimental animal by stimulation of the periaqueducatal gray. Attentuation of pain sensation may be due to the release of a neurotransmitter from interneurons in the dorsal horn of the spinal cord, which inhibits the release of neurotranmitters from the central axonal endings of the pain-sensing neurons. Which one of the following neurotransmitters is released from the interneurons in the dorsal horn?
A. Enkephalin
B. Ach
C. Endorphin
D. CGRP
E. Histamine
Enkephalin
Within the primary somatosensory cortex, the various parts of the contralateral body surface are represented in areas of varying size that reflect which of the following?
A. THe relative size of the body region
B. Density of the specialized peripheral receptors
C. Size of the muscles in that body part
D. Conduction velocity of primary afferent fibers
Density of the specialized peripheral receptors
Peripheral nerves are classified by two schemes: 1. their contribution to a compound AP and 2. Based on fiber diameter, myelin thickness, and conduction velocity. How are these two schemes related?
The conduction velocity determines a fiber’s contribution to the compoun action potential
A-alpha fibers have what two associated afferent fibers?
A-alpha fibers have what conduction velocity?
C fibers have what associated afferent fibers?
C fibers have what conduction velocity?
A-alpha
Ia and Ib
80-120 (fast)
C fibers
IV
0.5-2 (slow)
Which of the following peripheral nerve fibers supply primary muscle spindles and golgi tendon organ?
A. A-alpha
B. A-beta
C. A-delta
D. C fibers
A-alpha
Which of the following peripheral nerve fibers supply secondary muscle spindles and skin mechanoreceptors?
A. A-alpha
B. A-beta
C. A-delta
D. C fibers
A-beta
Which of the following peripheral nerve fibers supply skin mechanoreceptors, thermal receptors, and nociceptors?
A. A-alpha
B. A-beta
C. A-delta
D. C fibers
A-delta
C-fibers
There are two types of skin hairy and glabrous (ex. palms). Determine which of the following mechanoreceptors are found in glaborous skin? Which of the following is ONLY found in glabrous skin and not also hairy?
A. Meissner’s Corpuscle
B. Pacinian Corpuscle
C. Ruffini Corpuscle
D. Merkel Cell
E. Hair-follicle Receptor
F. Tactile Free-nerve ending
Meissner’s Corpuscle
Pacinian Corpuscle
Ruffini Corpuscle
Merkel Cell
All of the following mechanoreceptors have a low threshold, the top two are rapidly adapting, and the bottom two are slow adapting. My question is, which of the following senses magnitude and direction of stretch, as well as touch, pressure, and proprioception?
A. Meissner’s Corpuscle
B. Pacinian Corpuscle
C. Ruffini Corpuscle
D. Merkel Cell
Ruffini Corpuscle
- Meissner: touch and vibration (light flutter tapping; 100 Hz)*
- Pacinian: high frequency vibration (deep; 100-400 Hz)*
- Merkel: pressure*
Tactile acuquity is highest in what two locations due to their small receptive fields?
Tactile acquity is lowerst in what 3 locations due to their large receptive fields?
Fingertips and Lips
Calf, Thigh, Back
Which of the following is involved in the integration of the information for position sense as well as size, shape and discrimination? Where is this area located in the brain?
A. Somatosensory area I (S1)
B. Somatosensory area II (S2)
C. Parieto-temporal-occipital Association Area (PTO)
D. All of the above
Somatosensory area I (S1)
- located in the post central gyrus
- crude identification of senses, usually first stop for most cutaneus senses
Which of the following is responsible for comparisons between objects, different tactile sensations, and determining what becomes a memory? Where is this area located?
A. Somatosensory area I (S1)
B. Somatosensory area II (S2)
C. Parieto-temporal-occipital Association Area (PTO)
D. All of the above
Somatosensory area II (S2)
- Wall of the Sylvian Fissure*
- receives input from S1*
- important in cognitive touch*
- somatotopic representation is less maintained*
Which of the following is responsible for high-level interpretation of sensory inputs, receiving inputs from multiple sensory areas, and analyzing the spatial coordinates of “self” in the environment? Where is this area located?
A. Somatosensory area I (S1)
B. Somatosensory area II (S2)
C. Parieto-temporal-occipital Association Area (PTO)
D. All of the above
Parieto-temporal-occipital Association Area (PTO)
-
Phantom-Limb pain is a phenomenon where one feels pain in a body part that no longer exists. This phenomena is not that well understood, but one basic neuroprincple that is currently the most accepted is the Law of Projection. What is the Law of Projection?
The Law of Projection is the idea that if you stimulate the afferent tract along any area, you will feel the stimulation in the place that the inervation traditioanlly arises.
Which of the following is increased pain from a stimulus that normally provokes pain?
A. Hypersensitivity
B. Hyperaesthesia
C. Hyperalgesia
D. Allodynia
- A. Hypersensitivity: increased responsiveness of nociceptive neurons to their normal input*
- B. Hyperaesthesia: increased sensitivity to stimulation (excluding special senses)*
C. Hyperalgesia
D. Allodynia: pain due to a stimulus that normally doesn’t cause pain (sun burn and bed sheets)
What are the two fiber types that are related to the biphasic response to pain?
Which is responsibel for the sharp, phase one pain with a small receptive field?
Which is responsible for the dull, throbbing pain during phase 2? What substances does it release?
Alpha-delta
C-fibers: release Substance P, Glutamate, Aspartate, CGRP, VIP, NO
Transient Receptor Potential Family (TRP) are a family of receptor ion channels that are associated with pain. Which of the following TRPs is a ligand gated nonselective cation channel, that many C-fibers express? They are activated by exogenous compounds like capsaicin, as well as endogenous inflammatory compounds?
A. TRPV1
B. TRPA1
C. TRPM8
D. None of the above
TRPV1
Transient Receptor Potential Family (TRP) are a family of receptor ion channels that are associated with pain. Which of the following TRPs is involved in a number of inflammatory pain states like allergic contact dermatitis, chronic itch, painful bladder syndromes, IBS, and pancreatitis?
A. TRPV1
B. TRPA1
C. TRPM8
D. None of the above
TRPA1
Transient Receptor Potential Family (TRP) are a family of receptor ion channels that are associated with pain. Which of the following TRPs can be activated by dangerous and innocuous cold temperatures, as well as cooling agents like menthols?
A. TRPV1
B. TRPA1
C. TRPM8
D. None of the above
TRPM8
Describe Gate Control Theory and it’s relation to Cfibers?
Gate Control theory is the idea that without the input from C fibers, a tonically active interneuron suprresses the ascending pain pathway, closing the gate until a strong C-fiber activation opens the gate and pain is felt
Explain why “rubbing the spot that hurts” makes your arm feel better. Be sure to include the fibers, synapse locations, and substances involved in the somatosensory output
Rubbing the area of injury activated the A-Beta fibers (nonpainful stimulus or touch). These fibers branch in the dorsal horn and synapse on the inhibitory interneuron where it releases EAA. EAA activates the interneuron and triggeres the release of glycine, inhibitng the sedondary sensory neruon of the nociceptive pathway that the C-fibers synapsed with
During normal processing there is a Descending Inhibitory pathway that blocks pain. This descending pathway begins in the Paraqueductal gray and is activated by opiates, EAA, and cannabinoids. Descending projections are sent to the what two structures in the pons and medulla that release Serotonin and Norepinephrine in the dorsal horn in the spinal cord?
Serotonin and NE activate inhibitory interneuons and cause the release of opiates like enkephalin. Opiates then activate the Mu receptors that results in what effect?
Locus Coeruleus (Norepinephrine)
Raphe Nucleus (Serotonin)
Opiates activate mu receptors on C-fibers that reduces nociception in spinothalamic tract
Most visceral afferents are _______, and contribut to chronic visceral pain syndromes, while ___________ nociceptors are more involved in somatic chronic pain states like diabetic neuropathy.
Most visceral afferents are peptidergic, and contribut to chronic visceral pain syndromes, while non-peptidergic nociceptors are more involved in somatic chronic pain states like diabetic neuropathy.
Which of the following brain structures is particularly improtatnt in interpreting nociception, integrating all signals relating to pain?
A. Amygdala
B. S1
C. S2
D. Insular Cortex
E. Hypothalamus and Medulla
Insular Cortex
T/F: Visceral Inputs travels with autonomic nerves, and go to the hypothalamus and medulla to integrate physiological changes associated with visceral pain
True
Central Sensitization is activity dependent synaptic placicity in the spinal cord that generates post-injury pain hypersensitivity. How does Central Sensitization result?
What event leads to central sensitization?
Central sensitization reduces the threshold of dorsal horn neurons to noxious/painful sitmuli
Persistent stimulation of EAA receptors and constant proinflammatory signalling can lead to this sensitization
Peripheral Sensitization is a neuroplastic change that affects the level of expression of neurotransmitter. The activation of the neruoimmune system basically leads to more intense pain that last longer than normal. Describe what occurs at the original site of inflammation that is the key phenomenon of peripheral sensitization.
Prostaglandin E (PGE2) sensitizes peripheral nociceptors and reduces their activation threshold leading to increased and uneccesary responsiveness
NOTE: adjacent, non-injury primary afferent nerve fibers can become sensitized also
