Nervous System Various Terms Flashcards
efferent
carry away from a central structure
afferent
carry or move inward or toward a central structure
refers to certain arteries, veins, lymphatic vessels, and nerves
neurolgia
cells that support neurons and bind them to other neurons of other tissues of the body
term means “nerve glue”
supply nutrients and oxygen to neurons and assist in other metabolic activities; help with nervous system injury or infection
four major types: astrocytes; oligodendrocytes; microglia; ependyma
myelin sheath
white lipoid covering of axons that acts as an insulator to reduce the possibility of stimulating adjacent nerves
Schwann cell
cell that forms myelin sheath on axons in the peripheral nervous system
neurilemma or neurolemma
exterior surface of Schwann cells
oligodendrocytes
surrounds myelin sheath in central nervous system. do not produce neurolemma which makes nerve damage in central nervous system irreparable.
nodes of Ranvier
short unmyelinated spaces between adhacent segments of myelin sheath
synapse
functional connection between neurons or neurons and their targets
astrocytes
star shaped neurolgia that provide three dimensional mechanical support for neurons and form tight sheaths around the capillaries of the brain (blood-brain barrier).
perform phagocytic functions
oligodendrocytes
responsible for developing myelin on neurons of the central nervous system
microglia
smallest neurolgia
phagocytic and may become very active during times of in fection
ependymocytes
ciliated cells that line fluid filled cavities of the central nervous system, especially the ventricle of the brain; provide circulation of CSF
white matter
bundles of axons with their white lipoid myelin sheath
gray matter
unmyelinated fibers, dendrites, and nerve cell bodies
cerebrum
largest and uppermost portion of the brain
each of the two hemispheres has five lobes named after the bones that lie directly above them except for the insula
gyri
folds and convolutions in cerebrum
sulci
furrows or fissures that separate gyri
cerebral cortex
thin layer that covers entire cerebrum
Cerebellum
second largest structure of the brain
all functions involve movement
aids in maintaining equilibrium and balance
diencephalon (interbrain)
composed of many smaller structures including the thalamus and hypothalamus
thalamus
receives all sensory stimuli except olfactory and relays them to cerebral cortex
receives impulses from cerebrum and relays them to effernt nerves
hypothalamus
regulates activities of autonomic nervous system (ANS) including heartbeat, body temp, fluid balance; also endocrine functions
brainstem
consists of:
midbrain (mesencephalon)
medulla
pons
pathway for impulse conduction between the brain and spinal cord
controls the beginning of life and the end of life
origin of 10 of 12 cranial nerves
meninges
coverings of brain and spinal chord:
dura mater (pachymenengis)
arachnoid
pia mater
cerebrospinal fluid
colorless fluid that contains proteins, glucose, urea, salts, and some white blood cells
circulates around the spinal cord and brain and through ventricles in brain
provides nutrients
acts as a shock absorber
hydrpocephalus
fluid in the brain
pia matter
innermost meninx
directly adheres to brain and spinal cord
follows contours of gyri and sulci
leptomeninges
collective name for arachnoid and pia mater
peripheral nervous system
12 pairs of cranial nerves
31 pairs of spinal nerves
ANS and CNS
ANS
autonomic nervous system
sympathetic: fight or flight (immediate action)
parasympathetic: rest and digest
sensory nerves
afferent; receive impulses from sense organs
motor nerves
conduct impulses to muscles and glands
mixed nerves
composed of sensory and motor fibers; all spinal nerves are mixed
spinal nerves
two points of attachment to spinal cord: anterior (ventral) root and posterior (dorsal) root. the two roots unite to form mixed nerve
