Unit 2 Nervous Flashcards
neural tube gives rise to
CNS
which germ layer gives rise to the nervous system?
ectoderm
NS function
master controlling/communicating system of the body
cells communicate via electrical and chemical signals
NS cycle
sensory input
integration
motor output
sensory input
information gathered by sensory receptors about internal and external changes
integration
processing and interpretation of sensory input
motor output
activation of effector organs (muscles and glands) produces a response
NS characteristics
tissue almost entirely cellular, little ECM
cells chemically linked to form circuits
includes excitable cells; able to conduct stimulus
NS cell types
neuroglia (glial cells)
neurons (nerve cells)
neuroglia
small cells that surround and wrap delicate neurons
neurons
excitable cells that transmit electric signals
neurons
structural cells
large, highly specialized that conduct impulses
have cell body and process(es)
neuron characteristics
post mitotic
irritable
high metabolic rate
neuron components
prominent nucleolus
abundant RER and polyribosomes
axon
dendrite
axon
single process constant diameter conduct action potential away from body axon hillock axolemma axoplasm
dendrites
vary in number
tapers away
conducts graded potentials toward cell body
anatomical classification of neurons
bipolar
pseudounipolar
unipolar
multipolar
bipolar neuron
one dendrite
one axon
mostly sensory
e.g. cochlear, vestibular ganglia, olfactory mucosa, retina of eye
pseudounipolar
one branched process
found in dorsal root ganglia
contain central and peripheral process
synapse
site of contact between neurons and other cells
maintains unidirectional transmission of nerve impulse
synapse types
electrical
chemical
synapse sites
axodendritic
axosomatic
axoaxonic
electrical synapse
gap junctions between 2 neurons that allow for direct flow of the electrical current form one neuron to the next
chemical synapse
involves the release of neurotransmitters from synaptic vesicles
neuroglia cells
supporting cells of CNS
most numerous
mesoderm, phagocytes
neuroglia cell types
astrocytes
oligodendrocytes
microglial cells
ependymal cells
astrocyte types
protoplasmic: grey matter
fibrous: white matter
astrocytes
most numerous, versatile glial cells
- neuron development, synapse formation
- injury response
mediating exchange between neurons and blood supply
- blood brain barrier
- maintain neuronal microenvironment e.g. ion/neurotransmitter uptake, regulation of neuron metabolism
microglia
immune cells derived from monocytes
transform into macrophages
line ventricles of CNS
ependymal cells
sheets of simple cuboidal/columnar ET, often ciliated
secretion, maintenance, circulation of CSF
component of choroid plexus
oligodendrocytes
produce myelin
one can cover numerous axons
PNS neuroglia cells
Schwann cells
satellite cells
satellite cells
maintain neural microenvironment in ganglia; structural metabolic support
form complete layer around cell bodies of neuron in ganglia
Schwann cells
neurolemmocytes
Schmidt-Lanterman clefts
nodes of Ranvier
internodal segment
covers unmyelinated axons
white matter
mostly myelinated and unmyelinated axons plus neuroglia cells
deep portion of brain
superficial portion of SC
gray matter
neuronal cell bodies, axons, dendrites plus glial cells
sites of synapse in CNS
superficial brain (cerebral and cerebellar cortex)
deep portion of SC
gray matter
neuronal cell bodies, axons, dendrites plus glial cells
sites of synapse in CNS
superficial brain (cerebral and cerebellar cortex)
deep portion of SC
brain stem
pons
midbrain
medulla oblongata
cerebellar cortex
molecular layer - dendritic processes
purkinje layer
granular layer - sm neurons
fine motor control, posture
spinal cord
dorsal horn
ventral horn
lateral horn
central canal
dorsal horn
central processes of sensory (pseudo unipolar) neurons and interneurons
ventral horn
motor neurons to skeletal muscle
lateral horn
thoracic/lumbar
motor neurons of the sympathetic division of the ANS
central canal
lines with ependymal cells
continuous with brain ventricles
peripheral NS
spinal and cranial nerves
bundles of nerve fibers held together by CT
contain motor and sensory
epineurium
dense CT surrounds entire nerve
perineurium
surrounds individual bundles (fascicle) of fibers
endoneurium
surrounds individual nerve fiver and Schwann cells
ganglia
collections of neuronal cell bodies (grey matter) outside CNS
also contain glial cells and CT
sensory ganglia
associated with CN and dorsal root ganglion of spinal nerves
motor ganglia
ANS
parasympathetic
sympathetic
parasympathetic ganglia
in walls of organs, no capsule
sympathetic ganglia
thing CT capsule, multipolar motor neuron cell bodies, fewer satellite cells
dorsal root ganglion
sensory
pseudounipolar
numerous satellite cells
thick CT capsule
