Sensory Physiology Flashcards
These are specialized cells that generate graded potential called receptor potentials in response to a stimulus
Sensory receptors
What are the 5 major divisions of sensory receptors?
- Mechanoreceptors
- Thermoreceptors
- Photoreceptors
- Chemoreceptors
- Nociceptors
What are the 2 primary sensory codings?
Coding and Information
It is the conversion of a stimulus into a signal that is conveyed to the CNS
Coding
It is conveyed by both the frequency and amplitude of the resulting signals
Information
TRUE OR FALSE: Adaptation indicates that a decrease in receptor sensitivity, results in a decrease in action potential frequency in an afferent neuron despite a stimulus of constant strength
TRUE
What happens to stimulus intensity when the frequency of action potentials in a single afferent neuron is increased?
Stimulus intensity increases
TRUE OR FALSE: As the strength of a local stimulus increases, receptors on adjacent branches of an afferent neuron are activated.
TRUE
This is coded by the site of a stimulated receptor
Stimulus location
This depends upon the amount of convergence of neuronal input in the specific ascending pathway
Acuity
What happens when receptor endings of different afferent neurons overlap?
A stimulus will trigger activity in more than one sensory unit.
TRUE OR FALSE: A high action potential frequency in one neuron but low in others provide less accurate localization of the stimulus.
FALSE: More accurate
This enables the localization of a stimulus site
Lateral inhibition
Modification can come from four things, what are they?
- Inhibition from collaterals
- Pathways descending from the brain
- Synapses on the axon terminals
- Indirectly via interneurons that affect other neurons in the sensory pathways
A chain of three or more neurons that form an ASCENDING PATHWAY to the CNS
- First order neuron
- Second order neuron
- Third order neuron
Process may diverge to terminate on several interneurons
Divergence
Afferent neurons may terminate upon a single interneuron
Convergence
Where does the processing of afferent information occur?
Primary cortical receiving areas and Association areas in the cerebral cortex
Relies upon various association areas of the cortex to properly process sensory information
Primary Somatosensory Cortex
Factors that affect perception:
- Receptor adaptation and different processing
- Emotions and experiences
- Not all stimuli give rise to a conscious sensation
- Lack of receptors for certain stimuli
- Damaged neural pathways
- Drugs
Sensation from the skin, muscles, bones, tendons, and joints
Somatic sensation
Somatic sensation receptors respond to
- Touch and pressure
- Sense of posture and movement
- Temperature
- Pain
Rapidly adapting mechanoreceptor; touch, and pressure
Meissner’s Corpuscle
Slowly adapting mechanoreceptor; touch, and pressure
Merkle’s Corpuscle
Slowly adapting nociceptors, thermoreceptors, and mechanoreceptors
Free Nerve Ending
Rapidly adapting mechanoreceptor; vibration and deep pressure
Pacinian Corpuscles
Slowly adapting mechanoreceptor; skin strech
Ruffini Corpuscle
This differs from other somatosensory modalities
Pain
It can be altered by past experiences, suggestion, emotions, and the simultaneous activation of other sensory modalities
Pain
An increased sensitivity to painful stimuli
Hyperalgesia
The selective suppression of pain without effects on conscious or other sensations
Analgesia
Some mechanisms to achieve pain relief are:
- Electrical stimulation of the CNS
- Drugs: NSAIDs and Morphine
- Neurons in the inhibitory pathways that release morphine-like endogenous opioids
- Acupuncture
- Transcutaneous Electrical Stimulation (TEMS)
- Massage
This occurs when the brain is “confused” and you feel pain from an internal organ as another area of the body
Referred Pain