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
Astereognosis
· Inability to identify an object by touching/tactile stimuli even though primary sense data are intact
· Usually involves lesions to S2
What can parietal lobe damage result in?
Asterognosis or Agnosia
Visual Processing
· Right visual field gets processed in left side of brain
· Left visual field gets processed in right side of brain
(ex: right occipital cortex injury would result in left visual field deficit)
Retinal Photoreceptors Pathway to Cortex
1) Retinal Photoreceptors
2) Bipolar cells
3) Retinal ganglion cells (axons forms the optic nerve)
4) Lateral Geniculate Nucleus (of the thalamus)
5) Primary Visual cortex (of occipital lobe)
2 major brain processing pathways
1) Dorsal Pathway (vision for action)
- passes through PPC
- spacial recognition
- location matching
2) Ventral Pathway (vision for perception)
- object recognition
- face/location matching
Eye Defects
1) Myopia: near sighted (cant see distance)
2) Hyperopia: far sighted (cant see up close)
3) Astigmatism: cornea not spherical so impacts how light refracts into retina, light cant focus on just one point which causes blurriness and edges appear undefined
Eye Diseases
1) Cataract: clouding of the lens, causes blurry vision
2) Glaucoma: Pressure build up causing damage to retina, causes vision loss in periphery first
3) Macular Degeneration (2 types- wet or dry): causes blurriness in central vision, difficult in low light
4) Diabetic retinopathy: microaneurysms and hemorrhages causing damage to retinal cells and neurons, causing vision lost and blindness is affected areas
Vestibulo-Ocular Reflex (VOR)
· Stabilizes the eyes relative to external world
· Vestibular system detects brief changes in head position and quickly produces corrective eye movements in opposite direction
· Eyes move in opposite direction of head
VOR Cancellation
· Eyes move in same direction as head
· Cerebellum suppresses the VOR reflex
· Smooth Pursuit Cancellation
Optokinetic Reflex
· Eyes follow objects in motion while the head remains stationary
Optokinetic Nystagmus (OKN)
· Stabilizes gaze during movement of the large visual field
· Alternating pattern of slow and fast eye movements
· Eyes move in same direction as the image motion
Oculomotor Nerve Lesion Impairments
· Eyeball resting in “down and out” position and unable to elevate, depress, or adduct eye (due to paralysis of superior/inferior/medial rectus and inferior oblique)
· Dilated pupil
· Drooping of upper eye (ptosis)
Vertical Diplopia (double vision)
· Trochlear N lesion (Superior Oblique)
· double vision when looking down and in
Strabismus
· Abducens N lesion (Lateral rectus)
· most common ocular motor paralysis in adults
· eye pulled inward towards nose
General Components of Hearing
1) Outer ear: captures mechanical energy
2) Middle ear: transmits to ear’s receptive organs
3) Inner ear: transduces into electrical signals for the nervous system to analyze (involved in hearing and balance)
4) CNS
Central Auditory System
· Vestibulocochlear Nerve (CN 8):
- balance and hearing
- sensory nerve that carries signals from the cochlea to the brain
· Auditory Cortex (temporal lobe):
- part of brain where sound is perceived and analyzed
Primary auditory cortex lesion impairment
Deficits in processing information
Auditory Cortical Areas and Functions
· Wernicke’s area: interpretation of spoken words
· Broca’s area: speech production (motor)
4 Types of Hearing Loss
1) Conductive: sound waves dont make it to inner ear
·refer to PCP
2) Sensorineural: damage to inner ear or cochlear nerve
· Refer to neurologist
3) Mixed: conductive and sensorineural loss
·Refer to audiologist
4) Functional: patient doesnt hear or respond with emotional or psychological etiology
Auditory Pathologies
1) Peripheral
- congential hearing loss
- Presbycusis (age related)
- Vestibular or Facial Nerve
- Traume
- Infection/toxicity
2) Central
- CVA
- TBI
- Tumor