Chapter 10: Sensory Physiology Flashcards
what branch is involved in sensory physiology?
afferent branch of peripheral nervous system
conscious interpretation of the world based on sensory systems, memory, and other neural processes
perception
How does information travel?
- sent from periphery to CNS
- external environment (sensory receptors)
- internal environment
what are the sensory systems that enable us to perceive the external environment?
- somatosensory system
- somatic
- proprioception
sensations of the skin
somatic division of somatosensory system
perception of limb and body positions
proprioception division of somatosensory system
what are our special senses that help us perceive the external environment?
- vision
- hearing
- balance and equilibrium
- taste
- smell
- Detect specific form of energy in the external environment
- Modality: light, sound, pressure, temperature, chemicals
sensory receptors
a given sensory receptor is specific for each?
modality
is the modality that the receptor is most responsive.
adequate stimulus
modality that activates photoreceptors causing the perception of light
blow to the eye (pressure)
what are types of sensory receptors?
- chemoreceptors
- mechanoreceptors
- photoreceptors
- thermoreceptors
what are some stimuli for chemoreceptors?
- oxygen
- pH
- organic molecules
what are some stimuli for mechanoreceptors?
- pressure
- cell stretch
- vibration
- acceleration
- sound
what is the stimulus for photoreceptors?
photons of light
what is the stimulus for thermoreceptors?
varying degrees of heat
conversion of stimulus energy into electrical enery
sensory transduction
what are the potentials involved in sensory transduction?
- receptor or generator potentials
- graded potential
- opening or closing of ion channels
- triggered by sensory stimuli
what happens if the receptor potential exceeds the threshold?
- can generate an action potential
- release of neurotransmitters
what are the two basic forms sensory receptors exist in?
- neural sensory receptor
- sensory receptor cell
-neurons
with free nerve endings
-they may have myelinated or
unmyelinated axons.
simple receptors
have nerve
endings enclosed in connective tissue capsules
complex neural receptors
most special senses receptors are cells
that release neurotransmitter onto sensory
neurons, initiating an action potential
nonneural receptors
specific neural pathways transmitting information of a specific modality
labeled lines
what dos activation of a specific pathway cause?
causes perception of the associated modality, regardless of which stimulus actually activated the pathway
where do the pathways for different modalities terminate in?
different sensory areas of the cerebral cortex
-project to the thalamus
most sensory pathways
modifies and relays information to cortical centers
thalamus
project primarily to the cerebellum
equilibrium
what does a sensory unit include?
- single afferent neuron and all associated receptors
- all receptors are of the same type
- activation potential may result from activation of receptors
- receptive field
area in which a sensory unit is activated
receptive field
how the nervous system identifies the type, strength, and location of a stimulus
sensory coding
how is coding done for a stimulus type?
- receptor type activated (light waves)
- specific pathway (to visual cortex)
is perception based on a single sensory pathway?
no, brain must integrate info from different sensory systems
do we have wet receptors on our skin?
no
when activated, appropriately transmit a combination of signals that we interpret as wetness.
thermoreceptors and touch receptors
what is involved in coding for stimulus intensity?
- frequency of action potentials
- number of receptors activated
frequency of action potentials
frequency coding
number of receptors activated
population coding
how do stimulus and receptors correlate?
the stronger the stimulus, the more receptors it activates (recruitment)
-can be from same or other afferent neurons
A decrease over time in the magnitude of the receptor potential in the presence of a constant stimulus.
receptor adaptation
which receptors show little adaptation to a constant stimulus?
tonic receptors, muscle stretch receptors
which receptors adapt quickly to a constant stimulus?
phasic receptors, olfactory receptors
slowly
adapting receptors that respond
for the duration of a stimulus
tonic receptors
rapidly adapt to a
constant stimulus and turn off
phasic receptors
- based on receptive fields in somatic senses and vision (size of field & degree of overlap)
- acuity
- lateral inhibition
coding of stimulus location
precision with which a stimulus is perceived
acuity
what are the steps of lateral inhibition?
- primary neuron response is proportional to stimulus strength
- pathway closest to the stimulus inhibits neighbors
- inhibition of lateral neurons enhances perception of stimulus
what happens in somatosensory pathways?
- pain, temperature, & coarse touch cross the midline in the spinal cord
- fine touch, vibration, & proprioception pathways cross the mindline in the medulla
- sensory pathways synapse in the thalamus
- sensations are perceived in the primary somatic sensory cortex