Unit 2 Nervous Flashcards by Rochelle Guía

neural tube gives rise to

CNS

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which germ layer gives rise to the nervous system?

ectoderm

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NS function

master controlling/communicating system of the body

cells communicate via electrical and chemical signals

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NS cycle

sensory input
integration
motor output

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sensory input

information gathered by sensory receptors about internal and external changes

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integration

processing and interpretation of sensory input

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motor output

activation of effector organs (muscles and glands) produces a response

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NS characteristics

tissue almost entirely cellular, little ECM
cells chemically linked to form circuits
includes excitable cells; able to conduct stimulus

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NS cell types

neuroglia (glial cells)

neurons (nerve cells)

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neuroglia

small cells that surround and wrap delicate neurons

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neurons

excitable cells that transmit electric signals

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neurons

structural cells
large, highly specialized that conduct impulses
have cell body and process(es)

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neuron characteristics

post mitotic
irritable
high metabolic rate

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neuron components

prominent nucleolus
abundant RER and polyribosomes
axon
dendrite

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axon

single process
constant diameter
conduct action potential away from body
axon hillock
axolemma
axoplasm

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dendrites

vary in number
tapers away
conducts graded potentials toward cell body

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anatomical classification of neurons

bipolar
pseudounipolar
unipolar
multipolar

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bipolar neuron

one dendrite
one axon
mostly sensory
e.g. cochlear, vestibular ganglia, olfactory mucosa, retina of eye

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pseudounipolar

one branched process
found in dorsal root ganglia
contain central and peripheral process

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synapse

site of contact between neurons and other cells

maintains unidirectional transmission of nerve impulse

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synapse types

electrical

chemical

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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