Chapter 13 Flashcards
provides links from and to world outside body
PNS
all neural structures outside brain in PNS
sensory receptors (afferent)
peripheral nerves
associated ganglia
motor endings (efferent)
respond to touch, pressure, vibration, and stretch
mechanoreceptors
sensitive to changes in temperature
thermoreceptors
respond to light energy (ex. retina)
photoreceptors
respond to chemicals (ex. smell, taste, change in blood chemistry)
chemoreceptors
sensitive to pain-causing stimuli (ex. extreme heat or cold, excessive pressure, inflammatory chemicals)
nociceptors
respond to stimuli arising outside body
exteroceptors
contain receptors in skin for touch, pressure, pain, and temperature
exteroceptors
most special sense organs
exteroceptors
respond to stimuli arising in internal viscera and blood vessels
interoceptors (visceroceptors)
sensitive to chemical changes, tissue stretch, and temperature change
interoceptors (visceroceptors)
sometimes cause discomfort but usually unaware of their workings
interoceptors (visceroceptors)
respond to stretch in skeletal muscles, tendons, joints, ligaments, and connective tissue covering bones and muscles
proprioceptors
inform brain of one’s movements
proprioceptors
classification by receptor structure
simple receptors for general senses
receptors for special senses
has tactile sensations (touch, pressure, stretch, vibration), temperature, pain, and muscle sense
simple receptors for general senses
has modified dendritic endings of sensory neurons
simple receptors for general senses
vision, hearing, equilibrium, smell, and taste
receptors for special senses
simple receptors of the general senses are either ______ or ______.
nonencapsulated (free) or encapsulated
abundant in epithelia and connective tissue
nonencapsulated (free) nerve endings
most nonmyelinated, small diameter group C fibers; distal endings have knoblike swellings
nonencapsulated (free) nerve endings
responds mostly to temperature and pain; some to pressure-induced tissue movement; itch
nonencapsulated (free) nerve endings
cold receptors (10-40 C) in superficial dermis heat receptors (32-48 C)
thermoreceptors
outside temperature range activates ___(1)___ and causes ___(2)___
(1) nociceptors
(2) pain
vanilloid receptor
player in detection of pain
for nociceptors
ion channel opened by heat, low pH, chemicals (ex. capsaicin)
vanilloid receptor
responds to pinching, chemicals from damaged tissue, capsaicin
nociceptors (pain)
light touch receptors
tactile (merkel) discs
hair follicle receptors
location: exteroceptors, interoceptors, propioceptors
stimulus type: thermoreceptors, chemoreceptors, mechanoreceptors, nociceptors
body location: most body tissues, dense connective tissues, epithelia
free nerve endings of sensory neurons
location: exteroceptors
stimulus type: mechanoreceptors; slowly adapting
body location: basal layer of epidermis
tactile (merkel) discs
location: exteroceptors
stimulus type: mechanoreceptors; rapidly adapting
body location: in and surrounding hair follicles
hair follicle receptors
all mechanoreceptors in connective tissue capsule
tactile (meissner’s) corpuscles
lamellar (pacinian) corpuscles
bulbous corpuscles (ruffini endings)
discriminative touch
tactile (meissner’s) corpuscles
deep pressure and vibration
lamellar (pacinian) corpuscles
deep continuous pressure
bulbous corpuscles (ruffini endings)
proprioceptors
muscle spindles
tendon organs
joint kinesthetic receptors
muscle spindles
muscle stretch
tendon organs
stretch in tendons
joint kinesthetic receptors
joint position and motion
location: exteroceptors
stimulus type: mechanoreceptors; rapidly adapting
body location: dermal papillae of hairless skin (nipples, genitalia, fingertips, soles of feet, eyelids)
tactile (meissner’s) corpuscles
location: exteroceptors, interoceptors, some proprioceptors
stimulus type: mechanoreceptors; rapidly adapting
body location: dermis and hypodermis; periostea, mesentery, tendons, ligaments, joint capsules; abundant on fingers, soles of feet, external genitalia, nipples
lamellar (pacinian) corpuscles
location: exteroceptors and proprioceptors
stimulus type: mechanoreceptors; slowly or nonadapting
body location: deep in dermis, hypodermis, joint capsules
bulbous corpuscles (ruffini endings)
3 basic levels of neural integration in sensory systems
- receptor level
- circuit level
- perceptual level
receptor level
sensory reception and transmission to CNS
circuit level
processing in ascending pathways
perceptual level
processing in cortical sensory centers
produce a sensation
- stimulus applied in receptive field
- transduction occurs
- graded potentials reach threshold
- action potential
receptors have specificity for ______ ______.
stimulus energy
stimulus changed to graded potential (generator potential or receptor potential)
transduction
change in sensitivity in presence of constant stimulus
adaptation
in adaptation, receptor membranes become less ___(1)___ and receptor potentials decline in ___(2)___ or ___(3)___.
(1) responsive
(2) frequency
(3) stop
signal beginning or end of stimulus (ex. receptors for pressure, touch, and smell)
phasic (fast-adaption) receptors
adapt slowly or not at all (ex. nociceptors and most proprioceptors)
tonic receptors
pathways of 3 neurons conduct ______ ______ upward to appropriate cortical regions.
sensory impulses
conduct impulse from receptor level to spinal reflexes or 2nd order neurons in CNS
first order sensory neurons
transmit impulse to 3rd order sensory neurons
second order sensory neurons
conduct impulse from thalamus to somatosensory cortex (perceptual level)
third order neurons
interpretation of sensory input depends on specific location of target neurons in ______ ______.
sensory cortex
ability to detect a stimulus (requires summation of impulses)
perceptual detection
intensity coded in frequency of impulses
magnitude estimation
identifying site or pattern of stimulus (studied by two-point discrimination test)
spatial discrimination
identification of more complex aspects and integration of several stimulus properties
feature abstraction
ability to identify submodalities of a sensation (e.g., sweet or sour tastes)
quality discrimination
recognition of familiar or significant patterns in stimuli (e.g., melody in piece of music)
pattern recognition
warns of actual impending tissue damage for protective action
perception of pain
stimuli includes: extreme pressure, temperature, histamine, K+, ATP, acids, bradykinin
perception of pain
perception of pain: impulse travels on fibers that release neurotransmitters ______ and ______.
glutamate and substance P
some pain impulses are blocked by ______ ______ ______ (ex. endorphins)
inhibitory endogenous opioids
felt as vague aching, gnawing, burning
activated by tissue stretching, ischemia, chemicals, muscle spasms
stimulation of visceral organ receptors
pain from one body region perceived from different region
referred pain
______ and ______ travel in same nerves
visceral and somatic pain fibers
assumes stimulus from common (somatic) region
brain
cordlike organ of PNS
bundle of myelinated and unmyelinated peripheral axons enclosed by connective tissue
structure of nerve
loose connective tissue that encloses axons and their myelin sheaths
endoneurium
coarse connective tissue that bundles fibers into fascicles
perineurium
tough fibrous sheath around a nerve
epineurium
mixtures of afferent and efferent fibers and somatic and autonomic (visceral) fibers
most nerves
Classified according to direction transmit impulses
nerves
both sensory and motor fibers; impulses both to and from CNS
mixed nerves
impulses only toward CNS
sensory (afferent) nerves
impulses only away from CNS
motor (efferent) nerves
pure sensory (afferent) or motor (efferent) nerves are ______.
rare