neurologic system part 1 Flashcards
what does the PNS consist of?
cranial and spinal nerves
tell me about an afferent pathway
ascending; sensory to spinal column
tell me about an efferent pathway
descending; innervate effector organs
what does the somatic NS consist of and what does it control
motor and sensory pathways that regulate voluntary motor control of skeletal muscle
what does the autonomic NS consist of and what does it control
motor and sensory pathways that control the bodys internal environment through involuntary control of organ systems
what NS are the sympathetic and parasympathetic NS from
autonomic
how big are neurons
variable size and structure throughout the NS
what neurons continue to divide
olfactory
what are the cellular components of a neuron
microtubules, neurofibrils, and nissl substances
what do neurons do
receive, integrate, and transmit information to other cells throughout the body
what are the 3 main components of a neuron
dendrites, cell body, and axon
dendrites?
elongated processes that receive information from other neurons or the environment
where do axons conduct impulses
away from cell body
where is the cell body/soma located
mainly CNS
what are densely packed cell bodies in the CNS
nuclei
what are densely packed cell bodies in the PNS
ganglia
where do dendrites send impulses
cell body
axon hillock?
cone shaped, nissl free area where the axon leaves the cell body
axon initial segment?
area of axon with lowest threshold for stimulation so action potentials begin here
myelin?
segmented layer of lipid material that insulates the axon
what is myelin formed and maintained by
schwaan cells
endoneurium?
layer of CT around each axon
neurilemma?
thin membrane btwn myelin sheath and endoneurium
nodes of ranvier?
interruptions in the myelin sheath
saltatory conduction?
flow of ions btwn segments of myelin rather than along the entire length of the axon; skips over area of demyelination
are nodes of ranvier myelinated or unmyelinated
unmyelinated
what is divergence
ability of branching axons to influence many neurons; 1 cell body and many axons
what is convergence
branching of numerous neurons converging on one or a few neurons
what happens in MS
myelin sheath is destroyed with scarring and inflammtion; autoimmune disease
can cells grow back their myelin
yes
how are nuerons classified
structural; based on the number of processes extending from the cell body
3 types of neurons?
bipolar, multipolar, pseudounipolar
what type of neurons are motor neurons
multipolar
what type of neurons are sensory neurons
pseudounipolar
what neurons have 2 processes attached to an oval shaped cell body
bipolar
what does one process of the bipolar neuron function as? what does the other do?
1: dendrite which carries information from the periphery of the organism
2: axon carrying information towards the CNS
where are bipolar neurons found
retina of the eye and olfactory epithelium of the nose
which neurons are specialized?
bipolar because they are in the retina of the eye and olfactory epithelium of the nose
what neuron type is the main one in the mammalian CNS
multipolar
what does a multipolar neuron look like
single axon and multiple dendrites emerging from the cell body; vary in size, number, and length of processes depending on number of synaptic contacts they make with other neurons
what NS are pseudounipolar neurons located in
peripheral
where are pseudounipolar neurons located
cranial and spinal nerves
what does a pseudounipolar neuron look like
dendritic portion extends away from the CNS and axon portion projecting into the CNS
which cells in the NS are the nerve glue
neuroglia
what do neuroglia do?
support neurons of CNS and PNS
types of neuroglia?
astrocytes, oligodendroglia, microglia, and ependymal cells
which type of neuroglia has “end feet”
astrocytes
what do “end feet” connect to
BV in brain
what do “end feet” do?
regulate local blood flow to provide oxygen and nutrients to neurons in need
besides having end feet that regulate blood flow, what else do astrocytes do
release NT to neighboring neurons
who do astrocytes interact with?
several neurons and hundreds of thousands of synapses to properly integrate info
which neuroglia have metabolic, immunologic, structural, and nutritional functions?
astrocytes
what are microglia derived from
bone marrow precursors of monocytic lineage
what is the main effector cell in the CNS
microglia
what are microglia activated by
brain injury, infection, neuronal degeneration
where do microglia reside
brain
when microglia are activated what do they do
produce cytokines, upregulate MHC, proteinase production, and ROS
what do ROS do
remove dead tissue and destroy invading organisms and contribute to CNS damage
what are synapses
regions btwn adjacent neurons or a neuron and a muscle that allow them to communicate with one another
how are impulses transmitted across synapse
chemical and electrical conduction
what type of synapse deals with action potentials
electrical synapses
what type of synapse deals with NT
chemical synapses
what does an excitatory synapse do
increases probability the postsynaptic neuron will fire or that the muscle will move
what does an inhibitory synapse do
decreases probability the postsynaptic neuron will fire or inhibits motor function
where does the presynaptic neuron send information
postsynaptic
which synapses stop communication
inhibitory
what do NT act on
muscles
synaptic cleft
region btwn axon and motor end plate
what do vescicles do
pass NT from presynaptic membrane into synaptic cleft
how do vesicles release NT
exocytosis
where are Ach NT located?
neuromuscular junction, autonomic ganglia, parasympathetic neurons, motor nuclei of cranial nerves, caudate nucleus and putamen, basal nucleus of meynert, parts of lymbic system
where are NE NT located?
sympathetic NS, locus ceruleus, lateral tegmentum
where are dopamine (DA) NT located?
hypothalamuc and midbrain nigrostriatal system
where are serotonin (5-HT) NT located?
parasympathetic neurons in GUT, pineal gland, nucleus raphe magnus of pons
where are gamma-aminobutyric acid (GABA) NT located?
cerebellum, hippocampus, cerebral cortex, striatonigral system
where are glycine NT located?
spinal cord
where are glutamic acid NT located?
spinal cord, brain stem, cerebellum, hippocampus, cerebral
which hormone is the pleasure hormone
dopamine
which NT helps with GI issues
serotonin (5-HT)
