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29 Cards in this Set
- Front
- Back
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What do the Pacinian corpuscles receptors respond to? |
Sudden displacement of skin; high-frequency vibration |
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What happens when a touch receptor is stimulated? |
Sodium channels open in the axon, starting an action potential |
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What is the purpose of the onion-like outer structure of the Pacinian corpuscle? |
Provides mechanical support that resists gradual or constant pressure. Insulates. |
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What do the Merkel disk receptors respond to? |
Light touch. Eg. Someone gently strokes your skin |
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What is Capsaicin?
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A chemical found in hot peppers. Stimulates painful heat.
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Why can't you tickle yourself? |
When you touch yourself, your brain compares the resulting stimulation to the "expected" stimulation and generates a weaker somatosensory response. |
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How does information from touch receptors in the head enter the CNS? |
Through the cranial nerves. |
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How does information from touch receptors below the head enter the CNS? |
Enters the spinal cord and passes toward the brain through the 31 spinal nerves. |
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What happened to one patient who had an illness that destroyed all the myelinated somatosensory axons but spared his unmyelinated axons? |
He still felt temperature, pain, and itch (depends on unmyelinated axons). But no sense of touch (depends on myelinated). |
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What is the primary somatosensory cortex essential for? |
Touch experience |
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What happens if there is damage to the somatosensory cortex?
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It impairs body perceptions. |
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In what way is somatosensation several senses instead of one? |
We have several types of receptors, sensitive to touch, heat, and so forth, and different parts of the somatosensory cortex respond to different kinds of skin stimulation |
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What do thicker and faster axons convey? |
Sharp pain |
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What do thinner and slower axons convey? |
Dull pain, such as postsurgical pain |
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What is one important difference between the spinal paths for pain and touch? |
The pain pathway crosses immediately from receptors on one side of the body to a tract ascending the contralateral side of the spinal cord. Touch info travels up the ipsilateral side to the medulla, where it crosses to the contralateral side. |
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Which areas react not to the sensation of pain, but to its emotional associations? |
Several of the central nuclei of the thalamus, the amygdala, hippocampus, prefrontal coretex, and cingulate cortex. |
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Which areas react to painful stimuli, and memores of pain? |
The ventral posterior nucleus of the thalamus and the somatosensory cortex |
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What happens when you watch someone - especially someone you care about - experiencing pain? |
You experience sympathetic pain that shows up as activity in your cingulate cortex and other cortical areas. |
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In what ways are hurt feelings similar to physical pain? |
Hurt feelings activate the cingulate cortex, just as physical pain does. Also, acetaminophen relieves hurt feelings. |
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What are opioid mechanisms? |
Systems that respond to opiate drugs and similar chemicals |
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Which receptors do opiates bind to mostly? |
Receptors found in the spinal cord and the periaqueductal gray area of the midbrain. |
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What is the periaquductal gray area? |
A passageway of cerebrospinal fluid between the 3rd and 4th ventricles |
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What is the gate theory? |
Spinal cord neurons that receive messages from pain receptors also receive input from touch receptors and from axons descending from the brain. These other inputs close the "gates" for the pain messages by releasing endorphins. |
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what is a placebo? |
A drug or other procedure with no pharmacological effects. |
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How do nonsteroidal anti-inflammatory drugs, such as ibuprofen, relieve pain? |
By reducing the release of chemicals from damaged tissues. |
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Why is preferable to start taking morphine before an operation instead of waiting until later? |
The morphine will decrease the barrage of pain stimuli that might sensitize pain neurons. |
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What happens when you have mild tissue damage, such as when your skin is healing after a cut? |
Your skin releases histamines that dilate blood vessels and produce an itching sensation. |
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Do opiates increase or decrease itch sensations? |
Opiates increase itch by blocking pain sensations. Pain decreases itch |
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Suppose someone suffers from constant itching. What kinds of drugs might help relieve it? |
Histamines or capsaicin - depending on the source of the itch. Theoretically, drugs that block gastrin-releasing peptide might help. |
