intro to nervous system Flashcards
central nervous system
brain and spinal cord, integrating and command center
peripheral nervous system
nerves that exist form the brain & spinal cord, link all body regions to the CNS, contains ganglia
somatic body region
body wall (outer tube)
visceral body region
inner tube
somatic sensory
general: things you can feel on the outside of your body (touch, pain, vibration, pressure, temp)
special: hearing, equilibrium, vision
visceral sensory
general: widely felt in digestive & urinary tracts, reproductive organs (stretch, pain, temp, nausea, hunger)
special: taste & smell
somatic motor
“voluntary”, signals contraction of skeletal muscles
visceral motor
regulates contraction of smooth and cardiac muscle, makes up autonomic nervous system
axon
impulse generator & conductor away form cell body
dendrites
extensive branches from cell body, receive signals, transmit electrical signals toward cell body
synapses
site where neurons communicate
presynaptic neuron
conducts signal toward a synapse
postsynaptic neuron
transmits chemical or electrical activity away from synapse
sensory neurons (afferent)
make up sensory division of PNS, transmit impulses toward CNS from sensory receptors in the PNS
motor neurons (efferent)
make up the motor division of the PNS, carry impulses away from the CNS to effector organs (muscles & glands)
interneurons
located between motor and sensory neurons, synapse with sensory neurons, confined entirely to CNS
structure of a typical nerve
cordlike organs in PNS, consist of numerous axons arranged in parallel bundles and enclosed by connective tissue
reflex arcs
simple chains of neurons that explain reflex behaviors, reflect structural plan of nervous system, and are responsible for reflexes (rapid, involuntary responses to stimuli)
components of reflex arc
receptor site, sensory neuron, integration center, motor neuron, effector muscle or gland
receptor site
where stimulus acts
sensory neuron
transmits the sensory impulses to the CNS
integration center
one or more synapses in the CNS
motor neuron
conducts the motor impulses to the effector organ
effector muscle or gland
responds by contracting or secreting
dorsal roots
sensory fibers
ventral roots
motor fibers
spinal nerve proper
dorsal and ventral roots come together so each spinal cord has motor and sensory fibers, then each spinal nerve splits
dorsal rami
innervate the dorsum of neck and trunk
ventral rami
innervate the lateral and anterior regions of the neck, trunk, limbs
nerve plexus
regrouping of nerves that come together and intermingle their fibers and new named nerves come off of it, a network of nerves
nerve plexuses
formed from nerve plexus, cervical (neck), brachial (upper limb), lumbar (lower back & lower limb), sacral (pelvis & lower limb)
dermatome
skin innervated by sensory fibers of one spinal nerve
