Nerve Flashcards
neurons
networks of specialized cells that communicate with each other and to other parts of the body
functions of nervous system
-generate movement
-learn and remember
-comprehend and generate language
-make decisions based on goals
-etc
2 divisions of the nervous system
CNS and PNS
CNS
spinal cord and brain
PNS
sensory elements conducting info to CNS, motor elements that conduct signals from CNS to effector cells
PNS is divided into which 2 groups
autonomic and somatic
somatic nervous system
skeletal movement
autonomic nervous system
involuntary movement
2 divisions of the autonomic nervous system
sympathetic and parasympathetic
sympathetic nervous system
fight or flight
parasympathetic nervous system
rest and digest
main parts of a neuron
axon, dendrite, cell body
axon
sends signals out
dendrite
receives signals into cell body
3 different neuron morphologies
multipolar, bipolar, pseudounipolar
multipolar neuron
-most common neuron
-1 axon, 2 or more dendrites
bipolar neuron
-1 axon, 1 dendrite
-visual, olfactory systems
pseudounipolar
-1 axon that divides into 2 branches
-sensory ganglia of cranial and spinal nerves
pseudounipolar neurons have what kind of projections
peripheral projection (extends into peripheral tissue) and central projection (extends into CNS)
synapse
where neurons meet and communication occurs
what is found in a pre-synaptic terminal
vesicles with neurotransmitter (large dense core vesicles)
-mitochondria for ATP
what characterizes a post-synaptic terminal on a TEM
postsynaptic density, dendritic spine
where does the axon and skeletal muscle fiber connect
neuromuscular junction
the presynaptic terminal is also referred to as the
active zone
important neurotransmitters
acetylcholine, glutamate (excitatory), GABA (inhibitory)
what is used to load up neurotransmitters into a vesicle
Proton gradient
4 steps in vesicle transport
1) budding
2) movement
3) tethering/docking
4) fusion
which 2 proteins are involved in fusion
v-SNARE (synaptobrevin) and T-SNARE (syntaxin)
What do the SNARE proteins do
the binding of the 2 proteins binds the 2 membranes so that the neurotransmitter gets released
what protein is involved in docking
Rab effector (tethering protein)
steps involved for SNARE proteins controlling membrane fusion
zipping, hemifusion, fusion, fusion pore (porocytosis)
what is SNARE-dependent fusion dependent on
calcium
what happens at the synapse after depolarization
-voltage gated ca 2+ channels allow ca 2+ to flood in, cause vesicles to fuse to pre-synaptic terminal, exocytosis of vesicles
dendritic spines are the sites of what?
post-synaptic input
how does a voltage potential exist
because nervous systems have the ability actively distribute ions non-uniformly across the membrane
graded voltage change
spreads passively and declines with distance from site of input
glutamate input does what
graded potential depolarization
GABA input does what
graded potential hyperpolarization
what happens if excitatory inputs win
the axonal initial segment is has voltage gates Na+ channels that open when voltage goes above a threshold
action potential
all-or-none response that propagates to the end of the axon
-triggered when threshold is reached
what is very prevalent in neurons
cytoskeleton
nissl material
consists of RNA and free ribosomes
-basophilic (likes basic dyes)
-where protein synthesis occurs
where are most neuronal proteins made
cell body
axon initial segments contain high levels of what 2 things
Na+ and K+ channels
axonal transport is _____ dependent
energy
anterograde
cell body to axon tip direction
retrograde
axon to cell body direction
axonal transport relies on what
microtubules, kinesin and dynein motors
kinesin goes in which direction
anterograde
dynein goes in which direction
retrograde
dysfunction in axonal transport can lead to which diseases
diabetes, neuropathy, Huntington Disease, Alzheimer’s
how does rabies get into the brain and then to the body
virus travels up nerves retrograde to spinal cord and then brain
-leaves via anterograde down cranial nerves
where are myelin sheaths made in each type of NS
CNS= oligodendrocytes
PNS= Schwann cells
functions of astrocytes
-help form blood-brain barrier
-secrete neurotropic factors
-take up K+ neurotransmitters
in the PNS, Schwann cells myelinate……
1 region of one axon
myelin sheath is made of up what
mostly lipids, some proteins
2 roles of proteins in myelin sheath
extrusion of cytoplasm with a single wrap of myelin (myelin compaction)
-adhesive contacts between adjacent membrane layers
myelinated axons are more _____ and _____ than unmyelinated axons
faster and energy-efficient
why can’t you myelinate the entire axon?
because theres a limit on how much insulation myelin can provide while still allowing space for enough axons
Nodes of Ranvier
gaps between myelin that have Na+ channels and re-boost the action potential
saltatory conduction
hopping from node to node, causing propagation of the action potential
how many axons can a oligodendrocyte myelinate
more than 1, multiple axons
immune-mediated demyelinating diseases
MS ( Multiple Sclerosis) and Guillain-Barre syndrome
inherited demyelinating diseases
adrenoleukodystrophy, failure to generate plasmalogens
metabolic demyelinating diseases
Central Pontine Myelinosis
virus-induces demyelinating diseases
progressive multifocal encephalopathy
what is the most abundant glial cell
astrocytes
Blood Brain Barrier
helps determine brain interstitial fluid by restricting ionic and fluid movements
-protects brain from fluctuations in ionic compositions (can occur after a meal or exercise)
cells involved in BBB
tight junctions, capillary endothelial cell, basement membrane
types of transport in BBB
-paracellular
-lipid-soluble through diffusion
-active transport with proteins
-receptor-mediated transcytosis
-adsorptive transcytosis
astrocytes provide the neuron with what
neurotransmitters and energy
astrocytes mobilize ______ to produce ______
glucose, lactate
-allows glucose to be used for metabolism or to protect neurons from low glucose
which transporters do astrocytes express
glutamate, they take up excess glutamate and recycle it to glutamine
microglia
major immune cell in CNS
-embryonically derived, self-renewing tissue macrophage
-don’t differentiate
how are microglia activated
by physical injury, inflammation, infection
-changes from ramified to amoeboid
ependymal cells
epithelial layer that lines the ventricles of the brain and central canal of spinal cord
ventricular system
-produces CSF, which buffers and cushions spinal cord
what kind of epithelium are ependymal cells
simple cuboidal-columnar
-have microvilli and cilia
white matter
bundles of myelinated axons (has oligodendrocytes)
gray matter
collections of neuron cell bodies, and astrocytes
spinal ganglion
aka dorsal root ganglion
-cell bodies of sensory neurons, whose axons project into spinal cord via dorsal root
ventral root
projection of motor axons from spinal cord to innervate muscle
satellite cells
In PNS, surround nerve cell bodies
-provide trophic support to neurons
epineurium
encloses entire nerve
-dense irregular CT
perineurium
encloses each fascicle of nerve fibers
-makes up blood brain barrier
endoneurium
surrounds individual nerve fibers
-CT
schwann cells can also ensheath ______
nonmyelinated PNS axons
which axons can regenerate
PNS axons after injury
which axons can regenerate
PNS axons after injury
how do CNS axons regenerate
they do not regenerate
which part of the brain is shaped like a c and how is it best stained
hippocampus, Nissl stain
