Neuro: Lecture 3 - Sensory COPY Flashcards
Sensory system parts
Receptors, peripheral nerves, spinal cord, thalamus, cerebral cortex
Where is cerebral (somatosensory) cortex located?
Postcentral gyrus of parietal lobe
First order neurons
Brings info from sensory receptors to spinal cord or brainstem
-AKA primary afferent neurons, peripheral somatosensory axons
-Enter spinal cord through dorsal roots
Second order neurons
Conveys info between spinal cord or brainstem to thalamus
Third order neurons
Convey info from thalamus to cerebral cortex
Types of cutaneous information
Touch (tactile/mechanoreception), pain (nociception), temperature (thermoreception)
Discriminative/light touch
-Where am I being touched?
-What kind of touch?
Proprioception
-Sensory info from MSK system
-where body is in space, without vision
-Static and kinesthetic sense
What is proprioception based on?
-Stretch of muscles and skin
-Tension on tendons
-Positions of joints
-Deep vibration
Stimulus
-When applied to receptors, triggers graded membrane potential in receptor
-Change in environment that activates receptors
-Determines types of receptors activated and pattern of signal transmission
Receptors
-Converts stimulus energy into action potential (if stimulus is large enough)
-Respond to a specific type of stimuli
Conduction
Impulse over sensory pathways to CNS
Translation
-CNS receives impulse, integrates info and may prepare response
-Giving meaning to signal
-Receptor level, circuit level, perceptual level
Components of sensory system
Stimulus, receptor, conduction, translation
3 types of stimulus
Mechanical, chemical, thermal
If receptor potential exceeds threshold of trigger zone (-55 mV)
-Action potential is generated
-Receptor converts stimulus energy into action potential
Mechanoreceptors
Respond to mechanical deformation of receptor by touch, pressure, stretch or vibration
Chemoreceptors
-Respond to exogenous chemicals or substances released by cells, including damaged cells following injury or infection
-Includes taste and smell
Thermoreceptors
Respond to temperature
Proprioceptors
Found in muscles, tendons, ligaments (position and kinesthetic sense)
Photoreceptors
Vision
How do nociceptors work?
Each type of receptor has a subset of nociceptors that are sensitive to stimuli that either damage or have the potential to damage tissues
Mechanoreceptors are _____ to physical distortion
Highly sensitive (have a low threshold)
Meissner’s corpuscles function
-LIGHT TOUCH (superficial in skin)
-VIBRATION
-Texture
LVT