Chapter 8: Sensory Processing, Touch, and Pain Flashcards
Sensory Processing
Sensory receptor organs detect energy/substances
What question do sensory receptors answer?
What type of stimulus was that?
Where does sensory processing begin?
Receptor Cells
Sensory processing is ___ and ___.
- Selective
- Analytical
Sensory Receptor Organs
Organs specialized to detect a certain stimulus.
Receptor Cells
Cells within the organ that convert the stimulus into an electrical signal and transmit it back to the CNS.
Receptor organs are very ___.
diverse
What is an example of a receptor organ?
Eyes
Adequate Stimulus
A type of stimulus to which a sensory organ is particularly adapted.
What is an example of an adequate stimulus?
Light for your eye
How do you classify sensory systems?
- Type
- Specific modality
- Adequate stimuli
What is an example of the restricted range of sensory systems?
The frequency range for hearing (varies per species)
What type of energy do all senses use?
Action potential
Labeled Lines
The brain recognizes distinct senses because AP travel along separate nerve tracts.
Sensory Transduction
The conversion of electrical energy from a stimulus into a change in membrane potential in a receptor cell.
Generator Potentials
Local changes in membrane potential.
Pacinian Corpuscle
A skin receptor that detects vibration.
What happens when a stimulus is added to the corpuscle?
A graded electrical potential is produced.
Coding
Patterns of AP in a sensory system that reflect a stimulus.
Range Fractionation
Different cells have different thresholds for firing, over a range of stimulus intensities.
Why is range fractionation important?
Individual cells often cannot reflect the entire range of a stimulus.
Somatosensory System
Detects body sensations (touch and pain)
How is stimulus location determined?
The position of activated receptors.
Adaption
The progressive loss of response to a maintained stimulus.
Tonic Receptors
Show slow or no decline in action potential frequency.
Phasic Receptors
Display adaptation and decrease frequency of action potentials.
What is the purpose of adaption?
Shows changes in the environment.
Accessory Structures
Additional components attached to a primary organ.
Example of accessory structure
Eyelids
Central Modulation of Sensory Modulation
Higher brain centers suppress some sensory inputs and amplify others.
Sensory Pathway
Neurons connecting to other neurons.
Where do most neural pathways pass through?
Thalamus
Where do pathways terminate?
Cerebral Cortex
Receptive Field
The space in which a stimulus will alter a neuron’s firing rate.
What do receptive fields differ in?
- Size
- Shape
- Response types to stimulation
How can receptive fields be examined?
Experimentally
Initial Receptor Cell
Relatively small receptive field
- Cell fires more when stimulus occurs in its field
What happens when you move to higher level neurons?
You get larger receptive fields due to the convergence of input from multiple sensory cells.
Center Surround System
Stimulation of the center produces the opposite effect of stimulation in the surroundings.
What does the center surround system create?
A sharper contrast in sensation of the stimulus.
Primary Sensory Cortex
Exists for each modality
Secondary Sensory Cortex
Receives its main input from the primary cortical area for that modality.
Primary Somatosensory Cortex (S1)
Receives touch information from the opposite side of the body.
Secondary Somatosensory Cortex (S2)
Maps both sides of the body
What do association areas in the brain show?
A mixture of inputs from different modalities.
Polymodal Cells
Allow for inter-sensory interactions
Synesthesia
A stimulus in one modality creates a sensation in another.
Example of synesthesia
- A person may perceive colors when looking at letters
- Identify taste when hearing a tone
What system is touch a part of?
The somatosensory system
What are the 4 tactile receptors that perceive touch?
- Pacinian Corpuscles
- Meissner’s Corpuscles
- Merkel’s Discs
- Ruffini’s Endings
- Pacinian Corpuscles
Vibration, fast adapting
- Meissners Corpuscles
Touch, fast adapting
- Merkel’s Discs
Touch, slow adapting
- Ruffini’s Endings
Stretch, slow adapting
Dorsal Column System
Delivers touch information to the brain.
Dermatome
A strip of skin innervated by a particular spinal root.
How are brain regions arranged?
The body surface plan
What do brain regions reflect?
The density of body innervation.
What can change receptive fields?
Experience
What does the cortical map represent?
The innervation of a body region.
What happens to the cortical area when the body region is servered?
It shrinks
What happens when a body region is completely removed?
The cortical area for the adjacent regions will expand.
Pain
An unpleasant experience associated with tissue damage
Congenital Insensitivity to Pain
An inherited syndrome that can still discriminate touch.
Touch and pain are ___ systems.
separate
Nociceptors
Peripheral receptors that respond to painful stimuli.
Free Nerve Endings
Located in the dermis and have specialized proteins that respond to temp changes, chemicals, and pain.
Capsaicin
The “hot” in chili peppers
TRPV1
The receptor that binds to capsaicin.
- detects painful heat
TRP2
- Detects even higher temps
- Does not respond too capsaicin
Found on Ao Fibers
Ao Fibers
Large myelinated axons that register pain quickly.
Where are TRPV1 receptors located?
On C fibers
C Fibers
Thin, un myelinated axons that conduct slowly, producing lasting pain.
Cool Menthol Receptor 1 (CMR1)
Responds to menthol and cold temps
Where are CMR1 receptors located?
C Fibers
Anterolateral/Spinothalamic System
Free nerve endings that synapse on spinal neurons that transmit the sensations of pain and temperature.
Where is pain information integrated?
Cingulate Cortex
Analgesia
The loss of pain sensation.
Opioids
Drugs that control pain
Opioid Peptides
The endogenous neurotransmitters in the brain.
What are the three classes of endogenous opioids?
- Endorphins
- Enkephalins
- Dynorphins
Opioid Receptors
Respond to opiates/opioids
Periaqueductal Gray
An area in the midbrain involved in pain perception.
Transcutaneous Electrical Nerve Stimulation (TENS)
Delivers electrical pulses to the skin which relieve pain by stimulating the nerves around them.
Naloxone
An opioid antagonist that can block the pain relieving effects of TENS
TENS depends on…
Endogenous opioid release
Placebo
Can sometimes relieve pain even though it is an inherit substance
What type of pain do C Fibers relate to?
Long lasting pain
What type of pain do AO Fibers relate to?
Initial pain
What is releases to cause itching?
Histamine
What type of pain modulation system do we have?
Descending (brain sends signals down body)
Acupuncture
Relieves pain by inducing endorphin release
What supports the claim that “fake” acupuncture works just as well as “real” acupuncture
Placebos
