Question | Answer |
what makes up the peripheral nervous system? | all neural structures outside the brain: sensory receptors, peripheral nerves and associated ganglia, motor endings |
activation of sensory receptors results in what kind of potential? | graded; then triggers a nerve impulse |
receptors are classified based on what? | stimulus type, location, structural complexity |
what are the stimulus type classifications of receptors? | mechanoreceptors, thermoreceptors, photoreceptors, chemoreceptors, nociceptors |
Exteroreceptors respond to? | stimuli outside the body, touch, pressure, pain, temperature, most special sense organs |
interoceptors (visceroceptors) respond to? | stimuli arising in internal viscera and blood vessels, chemical changes, tissue stretch, temperature changes |
proprioceptors respond to? | stretch in skeletal muscles, tendons, joints, ligaments, connective tissue coverings; inform brain of movements |
Complex receptors are? | special sense receptors |
Simple receptors are? | general sense; tactile sensations, temperatur, pain, muscle sense; unencapsulated of encapsulated dendritic endings |
Unencapsulated dendritic endings refer to? | thermoreceptors; cold in superficial dermis and heat in deeper dermis; Nociceptors (pinching, chemicals, temp, capsaicin; light touch receptors (merkel discs, hair follicles) |
Encapsulated dendritic endings refer to? | all are mechanoreceptors (meissners, pacinian, ruffini, muscle spindles, golgi tendon organs, joint kinesthetics) |
sensation | awareness of changes in the internal and external environment |
perception | the conscious interpretation of stimuli |
what are the levels of sensory integration? | receptor level, circuit level, perceptual level |
adaptation | change in sensitivity in the presence of a constant stimulus |
phasic receptors | fast adapting receptors that signal the beginning or the end of a stimulus |
tonic receptors | slow adapting receptors that adapt slowly or not at all (nociceptors and most proprioceptors) |
first order neurons (circuit level) | conduct impulses from the receptor level to the second order neurons in the cns |
second order neurons (circuit level) | transmit impulses to the thalamus or cerebellum |
third order neurons (circuit level) | conduct impulses from the thalamus to the somatosensory cortex (perceptual level) |
perceptual detection (perceptual level) | ability to detect a stimulus (requires summation of impulses) |
magnitude estimation (perceptual level) | intensity is coded in the frequency of impulses |
spatial discrimination (perceptual level) | identifying the site or pattern of the stimulus (2 point discrimination test) |
feature abstraction | identification of more complex aspects and several stimulus properties |
quality discrimination | the ability to identify submodalities of a sensation (sweet or sour taste) |
pattern recognition | recognition of a familiar or significant patterns in stimuli (melody in music) |
how does perception of pain work? | impulses travel of fibers that release neurotransmitters glutamate and substance P |
how do opiods work on pain? | block pain impulses |
dorsal root ganglia | sensory, somatic |
autonomic ganglia | motor, visceral |
regeneration of nerve fibers involve coordinated activity of what 3 things? | macrophages, schwann cells, axons |
motor endings | pns elements that activate effectors by releasing neurotransmitters |
inborn (intrinsic reflex) | rapid, involuntary, predictable motor response to a stimulus |
learned (acquired) reflex | result from practice of repetition ex. driving |
how do strech reflexes work? | stretch activates muscle spindle, lla sensory neurons synaps directly with beta motor neurons in the spinal cord, beta motor neurons case the stretch muscle to contract |
all stretch reflexes are? | monosynaptic and ipsilateral |
reciprocal inhibition | lla fibers synapse with interneurons that inhibit the beta motor neurons of antagonistic muscles ex. patellar reflex |
golgi tendon reflexes | help to prevent damage due to excessive stretch, important for smooth onset and termination of muscle contraction |
what activates golgi tendon organs? | contraction or passive stretch |
superficial reflexes | elicited by cutaneous stimulation; depend on upper motor pathways and cordlevel reflex arcs ex. plantar reflex |
babinski's sign | plantar reflex gone wrong |
why does muscle tone lessen with age? | sensory receptors atrophy with age due to loss of neurons, decreased numbers of synapses per neuron, and slower central processing |