Exam 2 (Sensory, Pharmacology) Flashcards
Sensory Receptor
- First cell in any sensory pathway
- transforms a stimulus into electrical energy (signal)
- specialized
Labeled Line Code
(Sensory adaptaion/design)
How the brain associates a specific modality with a signal coming from a specific receptor
5 Specific Touch Receptor Types
Low threshold and rapidly adapting:
1) Meissner’s Corpuscles ·sensitive to touch and vibration
· Dense in tips of fingers
2) Pacinian Corpuscles
·sensitive to high freq vibration
Low threshold and slowly adapting:
3) Merkel’s Disks
·sensitive to pressure
4) Ruffins Corpuscles ·senstive to stretching of skin
Uncategorized
5) Hair follicles
2 Types of Proprioception
1) Conscious: info to cerebral cortex (dependent on joint receptors)
2) Non-Conscious: info to cerebellar cortex (mediated via muscle spindles and golgi tendon organ)
2 Types of Conscious Proprioception Receptors
1) Slowly Adapting- static aspects of kinesthesia (gives info over time)
· ex: posture
2) Rapidly Adapting- dynamic aspects of kinesthesia (consistently providing updates to brain)
·ex: smell of bakery is strong at first but then fades over time)
· What is Threshold?
·Low vs High Threshold
· Threshold: lowest stimulus intensity detectable half of the time (can be modified)
·Low Threshold- easy to excite
· High Threshold- more difficult to excite
How would impairments of conscious vs non-conscious proprioception appear?
1) Conscious: unsteady
2) Non-Conscious: staggered gait, uncoordinated
Sensation Mechanics
1) Threshold
2) Timing
3) Receptor Density and Field
Receptive Field
· Area of skin that, when stimulated, produces or changes responses in neuron
· Contains both excitatory and inhibitory neurons
· Small field, high density = strongest stimulus response (ex: tips of fingers)
Relationship between inhibition and Two-point discrimmination
·Two-point discrimination:
- function of receptor density and inhibition
- Strongest in feet, hands, face
- Weakest in back
· Lateral Inhibition enhances stimulus detection
What body part has higher density for touch receptors?
Finger tips
How do sensory impairments affect patients?
· Impacts ability to interact with outside world and sense position relative to it
· May have to sensitize patients
Dermatome
Innervation related to an individual dorsal root
Somatosensory Routes to Brain and Function
1) Dorsal Column Medial Lemniscal
· Discrimminative touch
· Vibration
· Conscious proprioception
· Joint and muscle sensation
· Kinesthetic sense (dynamic motion and movement awareness)
2) Anterolateral (General)
· Pain
· Pressure
· Temp
·Touch
Antereolateral Tract Functions
1)Anterior Spinothalmic Tract: crude touch, light touch, pressure
* AWARENESS AND RECOGNITION OF WHERE PAINFUL STIMULUS IS
2) Lateral Spinothalmic Tract: Pain and temp
* AWARENESS AND RECOGNITION OF WHERE PAINFUL STIMULUS IS
3) Spinoreticular Tract: emotional/arousal aspects of pain
* LEVEL OF ATTENTION TO PAIN
4) Spinomesencephalic Tract: control and inhibition of pain
* INHIBITION OF PAIN
Spinocerebellar Pathways
1) Dorsal Spinocerebellar Tract: unconscious proprioception to cerebellum, fine coordination of posture, LE movement
- UNCROSSED*
2) Ventral Spinocerebellar: simialr as above
Descending Modulation of Pain Pathways and Function
1) Serotonergic
2) Noradrenergic
Function: Inhibit 2nd neuron of Lateral Spinothalamic Tract, resulting in Analgesia (inability to feel pain)
Habituation vs Sensitization
· Habituation: decrease in response strength to a repeated stimulus
· Sensitization: increase in response strength to a repeated stimulus
Where does proprioception come from?
Receptors in muscles and joints
Somatic Sensation
Sensation about the body wall
Lesion to Posterior Parietal Cortex (PPC)
· Loss of association function (ex: feeling keys in pocket but unable to associate object with the name “keys”)
4 attributes of Stimulus Quality
1) Modality
2) Intensity
3) Location
4) Timing
4 Major Functions required to produce coherent sound
1) Increase size of receptor field
2) Influence of inhibition networks (help put focus on important things)
3) Sensory Cortex Hierarchy
4) Submodalities converge (brings the fragments together to make it make sense) (uni-modal becomes multimodal which allows for polysensory experience)
Affects of Cortical Sensory lesions
Sensory Impairments:
· Contralateral defecits
· Touch
· Position sense
· Stereognosis
· Two-point discrimmination