36 terms

nervous system

nervous system
chief coordinator, acts by chemical changes and electrical impulses
central nervous system
brain and spinal cord
peripheral nervous system
cranial nerves and spinal nerves
cranial nerves
carry impulses to and from the brain
spinal nerves
carry impulses to and from the spinal cord
somatic nervous system
controlled voluntarily, affects skeletal muscle
autonomic nervous system
involuntary, controls smooth muscle, cardiac muscle, and glands, has 2 subdivisions sympathetic and parasympathetic
sympathetic nervous system
prepares body for energy expending stressful or emergency situations
parasympathetic nervous system
maintains homeostasis, conserves body energy, more active under ordinary, restful situations
neuroglia or glial cells
fill spaces, support neurons, and insulate neurons, can reproduce, and act as phagocytes
nerve cell or neuron
functional unit of the nervous system, specialized to react to physical and chemical changes, functions to conduct nerve impulses to other neurons and to cells outside the nervous system
fibers that conduct impulses to the cell body, receive stimuli, receive changes
fibers (one per neuron) that carry impulses away from the cell body
myelin sheath
fatty material that insulates fiber, covers some axons
schwann cells
located in the myelin sheath, produces myelin, wraps around the axon
gaps between the schwann cells, important in speeding the conduction of nerve impulses
outermost membrane of schwann cells, thin coating, helps some peripheral nerves repair themselves after injury
white fibers
myelinated fibers found in the white matter of the brain and spinal cord
gray matter
has no myelin
sensory or afferent neurons
neurons that conduct impulses to the spinal cord and brain
motor or efferent neurons
carry impulses away from the CNS to muscles and glands
inside of neuron is negative, the oustide is positive (when neuron is at rest)
Na+ and K+
needed for nerve impulses, at rest Na are more concentrated on the outside of the membrane and K is more concentrated on the inside
action potential
the inside negative ions rush outside, and the outside positive ions rush inside
as the Na flow into the cell, they raise the charge on the inside of the membrane
K leaves the cell, electrical charge returns to its resting state, and Na and K return to original postitions on either side of the membrane
the junction between 2 neurons, or from a neuron to an effector cell
carry impulses across the gap (synapse) to the next cell
4 neurotransmitters
epinephrine, norepinephrine, dopamine, acetylcholine
neurotransmitters are turned off by?
enzymes, diffusion, recycled
spinal cord
long, thin nerve column, extends from foramen magnum to level of first lumbar vertebrae
how is spinal cord protected?
by vertebral column, meninges, and cerebral spinal fluid
reflex arc
afferent, efferent, RSCNE
receptor, sensory, CNS, motor neuron, effector
rapid, simple, automatic response, specific- a given stimulus always produces the same response
spinal nerves
31 pair, numbered according to the level of spinal cord where they originate, exit through vertebral column, branch out to body parts to connect them with CNS