chapter 15 Flashcards
what is the component of the efferent division of the nervous system
Somatic motor portion
Carries out somatic motor commands that control peripheral effectors
Commands travel from motor centers in brain along somatic motor pathways
what does somatic system mean
Controls contractions of skeletal muscles
defn what is transduction
Conversion of an arriving stimulus into an action potential by a sensory receptor
what is general sense
-Temperature
-Pain
-Touch
-Pressure
-Vibration
-Proprioception (body position)
what is special sense
-Olfaction (smell)
-Gustation (taste)
-Vision (sight)
-Equilibrium (balance)
-Hearing
what is receptor specificity
Each receptor has a characteristic sensitivity
Receptive field what is being monitored by and what makes it difficult to localize it
Area monitored by a single receptor cell
The larger the receptive field, the more difficult it is to localize a stimulus
what is the function of labeled line
Each labeled line carries information about one modality, or type of stimulus (e.g., touch or light)
adaption what does it do when constant stimulus and what does it adapt to
Reduction of receptor sensitivity in the presence of a constant stimulus
Nervous system quickly adapts to painless, constant stimuli
defn Phasic receptors
Provide information about intensity and rate of change of a stimulus, normally inactive
defn Slow-adapting receptors
Show little peripheral adaptation
what are the 4 main types of General sensory receptors
-Nociceptors (pain)
-Thermoreceptors (temperature)
-Mechanoreceptors (physical distortion)
-Chemoreceptors (chemical concentration)
what are Nociceptors, where are they most common in, and what are they sensitive to
pain receptors)
Free nerve endings with large receptive fields,
Are common
In superficial portions of skin
In joint capsules and within periostea of bones
Around walls of blood vessels
May be sensitive to
Temperature extremes
Mechanical damage
Dissolved chemicals (as released by injured cells)
what types of fibers and where do they relay info to what cortex of the Nociceptors
Myelinated Type A fibers, Carry sensations of fast pain (prickling pain) such as that caused by injection or deep cut
Unmyelinated Type C fibers Carry sensations of slow pain (burning and aching pain)
Relayed to primary somatosensory cortex and thus receive conscious attention
what is the thermoreceptors, where are the nerve endings, and in what pathway is it going?
temperature receptors
Free nerve endings located in
-Dermis
-Skeletal muscles
-Liver
-Hypothalamus
Sensations are conducted along same pathways that carry pain sensations
the function of mechanoreceptors, what are they sensitive to, and the 3 classes of it
Sensitive to physical stimuli that distort their plasma membranes
sensitive to
-Stretching
-Compression
-Twisting
-Other distortions of the membrane
the 3 classes of mechanoreceptors
- tactile receptors
-barorecptors
-proprioceptors
Tactile receptors
provide sensations of
Touch (shape or texture)
Pressure (degree of mechanical distortion)
Vibration (pulsing pressure)
Baroreceptors
Detect pressure changes in blood vessels and in digestive, respiratory, and urinary tracts
Proprioceptors
Monitor positions of joints and skeletal muscles
the chemoreceptors what do they respond to and what do they monitor
Respond to water- and lipid-soluble substances that are dissolved in body fluids
Monitor pH, carbon dioxide, and oxygen levels in arterial blood at
what does the Golgi do during muscles contraction and where
At junction between skeletal muscle and its tendon
Monitor tension during muscle contraction
the first oder of neuron deliver what
Sensory neuron that delivers sensations to CNS
the second order of neuron receives from which neuron and what does it crosses
interneuron in spinal cord or brainstem that receives information from first-order neuron
Crosses to opposite side of CNS (decussation)
the third oder of neuron what does it receives and what sensation does it reach
Neuron in thalamus that must receive information from second-order neuron
For the sensation to reach our awareness
the sensory homunculus which column pathway is, which cortex, and to what is density to?
posterior column pathway
Functional map of primary somatosensory cortex
Area devoted to a particular body region is
Proportional to density of sensory neurons
Not proportional to region’s size
spinothalamic pathway what does it carry
Carries sensations of crude touch, pressure, pain, and temperature
what does the posterior column pathway
Carries sensations of fine touch, vibration, pressure, and proprioception
Anterior spinothalamic tract
Crude touch and pressure
Lateral spinothalamic tract
Pain and temperature
the somatic sensory pathway are the two
Always involve at least two motor neurons
Upper motor neuron
Lower motor neuron
upper motor neuron where does It lies in, what are the activity
Cell body lies in a CNS processing center
Synapses on lower motor neuron
Activity may facilitate or inhibit lower motor neuron
the lower motor neuron were does it lies, what does innervate, what does it trigger
Cell body lies in a nucleus of brainstem or spinal cord
Only the axon extends outside CNS
innervates a single motor unit in a skeletal muscle
Activation triggers a contraction in innervated muscle
Damage eliminates voluntary and reflex control over innervated motor unit
Cerebellum monitors
Proprioceptive (position) sensations
Visual information from eyes
Vestibular (balance) sensations from internal ear
