Exam 4- Sensory Flashcards
sensory receptors
neural structures that respond to stimuli by generating an action potential
function of sensory receptors
they can lead to, but do not directly provide themselves, sensation (awareness of stimuli) and perception
how are sensory receptors classified?
type of stimuli they detect
location
structural complexity
sensory receptors classified by structural complexity
simple receptors
complex receptors
sensory receptors classified by stimulus detected
mechanoreceptors thermoreceptors photoreceptors nociceptors chemoreceptors
sensory receptors classified by location
exteroreceptors
interoreceptors
proprioceptors
simple receptors
modified dendritic endings of sensory neurons
complex receptors
localized collection of cells associated with the special senses
(sense organs like eyeballs, ears, taste buds, olfactory receptors, etc)
what does a stimulus to a sensory receptor result in?
generator potential (excitatory or inhibitory)
mechanoreceptor
stimulus: mechanical energy/force
thermoreceptor
stimulus: thermal/heat energy
photoreceptor
stimulus: light energy
nociceptor
stimulus: pain or potentially dangerous stimuli
chemoreceptor
stimulus: chemical energy
if any receptor is overstimulated, it sends what type of signal?
pain
exteroceptor
stimulus is outside the body
ex: touch, pain, pressure, temp, sight, etc
interoceptor
stimulus is within body
ex: stretch, temp, chemical, etc
proprioceptor
stimulus is within muscles, joints, tendons, ligaments, and connective tissue
detects stretch and is involved with balance
free nerve endings
dendrite is available to be stimulated (no connective tissue wrapping)
do not have complex sensory structures
sensitive to painful stimuli, hot/cold, light touch
examples of receptors with free nerve endings
merkel discs
hair follicle receptors
itch receptors
merkel discs
sensory cells in deep epidermis that respond to light touch
nerve ending is free
hair follicle receptors
around base of hair follicle
detect when hair is bent
nerve ending is free
itch receptors
stimulated by touch (things like the sensation when you feel wool)
in dermis
nerve ending is free
encapsulated dendritic endings
dendrites are enclosed in connective tissue
have either a brush border or fluid-filled sacs at ends
examples of receptors with encapsulated dendritic endings
meissners corpuscles pacinian corpuscles ruffinis corpuscles muscle spindles golgi tendon organs joint kinesthetic receptors
meissners corpuscles
light touch receptors in superficial dermis
nerve ending is encapsulated
pacinian corpuscles
deep pressure receptors in deep dermis
nerve ending is encapsulated
ruffinis corpuscles
stretch receptors; found in CT
nerve ending is encapsulated
muscle spindles
detect stretch in muscle
nerve ending is encapsulated
golgi tendon organs
detect stretch in tendons
nerve ending is encapsulated
joint kinesthetic receptors
detect stretch in articular capsule of synovial membrane of joint
nerve ending is encapsulated
somatosensory system
part of the sensory system that serves the body wall and limbs
somatosensory system requires neural integration at the ___ level, ___ level, and ___ level
receptor; circuit; perceptual
stimulation of sensory receptors occurs at which level of neural integration of the somatosensory system?
receptor level processing
receptor level processing
- receptor must be receptive (specific) to stimulus
- stimulus must be applied within receptive field
- stimulus transducer into receptor potential
- electrical impulse/generator potential produced
- must get to threshold & be depolarizing to initiate action potential - action potential produced
- neurotransmitter released at synapse
ascending pathways sending information up spinal cord to brain to appropriate regions of the cerebral cortex occurs at which level of neural integration of the somatosensory system?
circuit level
circuit level processing
- 1st-order neurons carry signal to spinal cord
- 1st-order synapse with 2nd-order neurons in spinal cord or medulla (unless part of spinal reflex)
- 2nd-order neurons carry impulse to thalamus or cerebellum
- 2nd-order synapse with 3rd-order neurons if in thalamus
- transmit signal to somatosensory cortex of cerebrum
perceptual level processing
message to cortex is always action potential
sensation is determined based on what part of cortex receives the impulse
done by 3rd order neurons
projection
project action potential to a certain part of the brain
types of receptors in receptor-level processing
tonic receptors
phasic receptors
tonic receptors
generate nerve impulse at constant rate, unless altered
(a nerve impulse is always being sent)
always on, we just change the rate
adapt slowly
equilibrium maintenance in the ears is an example of tonic receptors or phasic receptors?
tonic receptors
phasic receptors
normally off, unless activated/stimulated
adapt rapidly
adaptation
reduction in sensitivity in the presence of a constant stimulus
when a receptor is constantly stimulated, they stop sending signals
t/f nociceptors do not adapt at all
true
aspects of sensory perception
perceptual detection magnitude estimation spatial discrimination feature discrimination quality discrimination pattern recognition
perceptual detection
ability to detect that a stimulus has occurred somewhere
magnitude estimation
detects quantity of stimulus aka # of action potentials in cerebral cortex
frequency tells us how strong stimulus is
spatial discrimination
detecting which part of our body is being stimulated
based on which part of cerebral cortex is receiving stimulus
feature abstraction
distinguish different things we’re touching, based on the association area
“touch determination”
which aspect of sensory perception allows you to tell you’re touching sandpaper even when blindfolded?
feature abstraction
quality discrimination
“submodalities”
sour vs bitter, high pitch v low pitch
pattern recognition
ability to recognize different patterns
recognize familiar vs unfamiliar things, recognize things of importance to us
related to “learned” portion of brain
which aspect of sensory perception allows you to remember the melody to a song?
pattern recognition
nerve
cordlike organ of PNS
parallel bundles off peripheral neurons enclosed by successive wrappings of CT
can only carry impulse in 1 direction (toward or away from CNS)
ganglion
collections of neuron cell bodies associated with peripheral neurons
classifications of nerves
sensory (afferent)
motor (efferent)
mixed
sensory (afferent) nerves
toward CNS
away from PNS
optic nerve is an example of which nerve classification?
sensory nerve
motor (efferent) nerve
away from CNS
toward PNS
mixed nerves
most of the nerves in our body
components of sensory and motor neurons
more efficient than motor or sensory
what is nerve regeneration?
regeneration is limited to all damaged areas of nerve EXCEPT the cell body
primarily in PNS
why does nerve regeneration not occur in cell body?
if cell body dies, the neuron dies
the connected neurons also die if they exclusively receive impulses from the “dead” neuron
why is nerve regeneration primarily a process of PNS?
damage in CNS neurons has low chance for regeneration (longer neurons)
damage to PNS neurons has higher chance for regeneration depending on where damage occurred
process of nerve regeneration
- peripheral axon injured
- separated ends seal and swell
- Wallerian regeneration occurs
- surviving Schwann cells proliferate and migrate to injury site (replicate)
- schwann cells release growth factors and CAMS (cell adhesion molecules) and form regeneration tube
wallerian regeneration
phagocytes degrade axon, but neurolemma within endometrium remains intact
(axon and axon sheath in area of damage degenerate)
what happens after regeneration tube is formed in nerve regeneration
axon starts regenerating itself from the damage proximal to the cell body, outward toward part of break distal to cell body
