Week 1 (Test 1) Flashcards
pro(s)-
in front
tel(e)-
far
di(a)-
across or through
mes-
in the middle
rhomb-
in the for of a diamond (shape of the 4th ventricle)
met(a)-
after
myel-
marrow
rostral=
toward the nose
caudal=
toward the tail
dorsal=
toward the back
ventral=
toward the belly
-fugal
leaving from
-petal
arriving to
funiculus
a bundle of axons, like a cord
column
a funiculus directed ventrally
soma
cell body
the gray matter consisting of abundant somata at the surface of the cerebrum and cerebellum as opposed to white matter that is located deeper and consists of abundant fibers
cortex
net like, a loose arrangement of somata and dendrites intermingled with passing fibers
reticular
a fiber bundle which connects homtopic (same) regions across the midline
commissure
a crossing of the midline by fibers usually in the shape of an X
decussation
a deep sulcus
fissure
a convolution (coil or twist), especially of the brain
gyrus
somata in cerebral cortex
upper motor neurons
somata in the brainstem motor nuclei and spinal cord ventral horns; send their axons out of the central nervous system in peripheral nerves to innervate skeletal muscle
lower motor neurons
a term applied to the structure composed of the medula, pons, and midbrain
brain stem
hind brain
medulla
the part of the brainstem that bridges between the midbrain and the medulla
pons
What is Broca’s area?
the motor region for speech formulation and defines the dominant hemisphere
What is Wernicke’s area?
region concerning the sense of hearing, which functions in the interpretation of speech
What two important sets of arteries supply the entire brain?
internal carotid arteries and vertebral arteries
What is an ischemic stroke?
caused by a blood clot that blocks or plugs a blood vessel in the brain
What is a hemorrhagic stroke?
caused by a blood vessel that breaks and bleeds into the brain
the receptor itself is an ion channel
ionotropic
The receptor is linked to an ion channel with the help of a G-protein
metabotropic
directly coupled (fast)
ionotropic
second messenger mediated (slow)
metabotropic
Remember: excitation or inhibition is determined by the _____________ involved and NOT by _______
receptor NOT the neurotransmitter being released
What does an excitatory neurotransmitter cause?
depolarization of the membrane towards firing threshold
What does an inhibitory neurotransmitter cause?
hyperpolarization of the membrane away from firing threshold
What is unique about peptide neurotransmitters?
1) Synthesis directed by mRNA 2) Usually exist as inactive precursor proteins first 3) Made in the cell body and transported to the axonal terminal (instead of made in the terminal) 4) During the transport, they are cut into smaller pieces because of peptidase activity. They become active after this process.
What are the common catecholamine neurotransmitters?
dopamine, norepinephrine, and epinephrine
What are catecholamines derived from?
tyrosine
What is the rate limiting enzyme for catecholamine synthesis and what does it do?
tyrosine hydroxylase; puts the 2nd -OH onto the benzene ring of the tyrosine molecule
What is the precursor for serotonin?
tryptophan
What is the precursor for histamine?
histidine
What is the precursor for acetylcholine?
choline; it is not an amino acid or derived from an amino acid
What is the rate limiting step for synthesis of acetylcholine?
uptake of choline
The nicotinic receptor for Acetylcholine is ____.
ionotropic
The muscarinic receptor for acetylcholine is ____.
metabotropic
What is the degradative enzyme for acetylcholine?
acetylcholine esterase (AChE)
____ is considered an excitatory neurotransmitter because all of its receptors lead to depolarization.
glutamate
What is the precursor for glutamate?
glutamine
What happens to glutamate after its function is completed?
taken up by axon terminal and recycled
What is the ionotropic receptor for glutamate?
NMDA receptor Non-NMDA receptor
What is the metabotropic receptor for glutamate?
IP3, diacylglycerides are released after the receptor is activated
This receptor is important for learning and memory.
NMDA (N-methyl-D-aspartate) receptor
List the important properties of NMDA (N-methyl-D-aspartate) subtype of inotropic glutamate receptors. (5 things)
1) activated by endogenous release of glutamate 2) - requires co-activation of its glycine binding site 3) - requires partial depolarization of the membrane before it can be activated 4) - ligand binding causes the opening of a non-specific cation conducting channel (can release Ca2+ or Na+) 5) - second messenger effect of Ca2+ influx (calcium influx can lead to generation of NO)
____ is considered as an inhibitory neurotransmitter because all of its receptors lead to hyperpolarization.
GABA
What is the precursor for GABA?
glutamate
What is the ionotropic receptor for GABA?
GABAa receptor; leads to Cl- influx, thus hyperpolarization
What is the metabotropic receptor for GABA?
GABAb receptor; leads to K+ efflux, thus hyperpolarization
_____ is considered an inhibitory neurotransmitter because activation of its receptor leads to hyperpolarization.
glycine
What does glycine receptor activation result in?
leads to Cl- influx, thus hyperpolarization
What is the major inhibitory neurotransmitter in the spinal cord?
glycine
acts as a retrograde messenger (goes from postsynaptic cell to presynaptic cell)
nitric oxide
blocks binding of ACh to its nicotinic receptor in the neuromuscular junction
alpha-bungarotoxin
increases the frequency of GABAa Cl- channel opening
benzodiazepine (valium)
prevents the release of ACh from the nerve terminal
botox (botulinum toxin)
irreversibly inactivates acetylcholinesterase
organophosphates (insecticides)
blocks serotonin reuptake so that the neurotransmitter remains active longer
Zoloft (and other anti-anxiety agents)
muscarinic receptor blocker (used clinically to block postganglionic parasympathetics)
atropine
GABAb agonist (used clinically to treat spasticity and some forms of epilepsy)
Baclofen
increase the duration of GABAa Cl- channel opening
Barbiturate sedatives (Phenobarbital)
blocks monoamine re-uptake at synapse to prolong action of neurotransmitters
cocaine
blocks binding of acetylcholine to its nicotinic receptor on skeletal muscle
curare
-acts as an agonist at postsynaptic serotonin receptors
LSD
mimics binding of opioid peptides to their receptors to produce analgesia
morphine
- inhibit acetylcholinesterase activity, prolonging acetylcholine activity
Neostigmine
a NMDA glutamate receptor blocker
Phencyclidine (PCP, “angel dust”)
-glycine receptor blocker (ingredient in rat poison)
Strychnine
block monoamine uptake
tricyclic antidepressants
What brain structures are supplied by the internal carotid artery?
The carotid artery supplies the eye, frontal cortex, and portions of the temporal and parietal lobes.
Nissl bodies and ribosomes are found in all parts of a neuron with the exception of the ____.
axon
What is the function of oligodendrocytes?
myelination of CNS axons
Microglia are of ____ origin.
mesodermal; vs. ectodermal origin, like the rest of the CNS
What is the resting membrane potential for mammals?
-70mV
What causes the absolute refractory period?
In neurons, it is caused by the inactivation of the Na+ channels that originally opened to depolarize the membrane. These channels remain inactivated until the membrane hyperpolarizes. The channels then close, de-inactivate, and regain their ability to open in response to stimulus.
What causes the relative refractory period?
K+ channels remaining open lead to hyperpolarization. During this hyperpolarization, another action potential could be generated, but it would take a stimulus that is larger than normal since the membrane potential is not at its resting level
conduction of an action potential away from the soma (normal)
orthodromic conduction
conduction of an action potential towards the soma
antidromic conduction
Local anesthetics block what?
voltage gated Na+ channels
What is another name for the cell body of a neuron (besides soma)?
perikaryon
What type of neurons compose sensory ganglion?
pseudounipolar
What causes Myasthenia Gravis?
Antibodies to ACh Receptors on Skeletal Muscle Cell Membrane (i.e., on postsynaptic membrane)
sense light touch
Messner’s Corpuscle
sense deep touch and vibration
Pacinian Corpuscle
What is Wallerian Degeneration?
is a process that results when a nerve fiber is cut or crushed, in which the part of the axon separated from the neuron’s cell body degenerates distal to the injury.[1] This is also known as anterograde or orthograde degeneration
What is Central chromatolysis?
retrograde degeneration
weakness is distal and asymmetrical
neuropathies
Weakness is proximal and symmetrical
myopathies
Purkinje motor neurons are found where?
cerebellum
Pyramidal motor neurons are found where?
cerebrum (upper motor neurons)
Alpha motor neurons are found where?
brainstem & spinal cord (lower motor neurons)
If something is wrong with purkinje motor neurons, what would you see?
you would see ataxia or tremors
If something is wrong with pyramidal motor neurons, what would you see?
You would get spasticity (muscles contracting really hard)
If something is wrong with alpha motor neurons, what would you see?
you would see muscle twitching
What neurotransmitters are used in the parasympathetic branch of ANS?
ACh exclusively
For the autonomic nervous system, what is the location of preganglionic cell bodies?
CNS
For the autonomic nervous system, what is the location of postganglionic cell bodies?
peripheral nervous system
What neurotransmitters are typically used in the sympathetic branch of ANS? What are the exceptions to this?
typically ACh at the ganglion and norepinephrine at the target cells; Exception: Sweat glands and chromatin cells in the adrenal medulla use ACh exclusively
Sympathetic neurons exit via the lateral horns of the spinal cord at what vertebral level?
T1-L2
of bone marrow origin (mesodermal origin)
microglia
Stain positive for glial fibrillary acidic protein (GFAP)
astrocytes
Have MHC-I and MHC-II and are infected by HIV
microglia
What forms the blood - CSF barrier?
tight junctions between choroid epithelial cells
What composes the choroid plexus and what does it do?
pia, ependyma, and blood vessel it makes CSF (~20ml/h)
This ion causes the majority of inhibitory potentials
chloride
What is the rate limiting step for dopamine/NE?
tyrosine hydroxylase
What is the rate limiting step for serotonin?
Tryptophan hydroxylase
What is the rate limiting step for ACh?
choline transport uptake
The type of astrocytes found in white matter
fibrous
the type of astrocytes found in gray matter
protoplasmic
What intercellular connections are responsible for Blood-Brain barrier?
Endothelial cell tight junctions-Zona occludens Supported by astrocytes. Nurturing role
a dense network of neurons and glia in the central nervous system
neuropil
All CSF made in the brain has to find its way out through these two foramen.
Foramen Magenie and Foramen Luschka
What is the earliest sign of irreversible neuron death?
eosinophilic neuronal necrosis (red neurons)
What causes axonal spheroids?
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occurs when an axon is transected and all the axonal transport material traveling from the cell body towards the synapse starts accumulating at the site of the injury, since it can’t move any further
What is this? What is it diagnostic of?
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Lewy body; Parkinsons
What is this? What is it diagnostic of?
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Pick body; Pick’s disease/frontotemporal lobar degeneration
What is this? What is it diagnostic of?
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neurofibrillary tangle; Alzheimer’s
•Secondary degeneration of a neuron connected to a dying neuron
trans-synaptic degneration
What is this?
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Creutzfeldt astrocyte
What is this? What is it diagnostic of?
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This one shows peculiar circular multilayered proliferations of Schwann cells (the myelin-producing cells in the PNS), forming a structure called “onion bulb”. This appearance is diagnostic of a genetic disease called Charcot-Marie-Tooth disease, but it can also be seen in CIDP (chronic inflammatory demyelinating polyneuropathy), with some differences.
What are the key functions of astrocytes?
- Scavenge for IONS & Neurotransmitters
(K+, GABA, Glutamate)
- • Glycogen Storage and Release
- •VIP & NE = Release
- Tell Endothelial cells to form Blood Brain Barrier (ZO)
- GLIAL SCAR Formation (Prevents CNS Axon Regeneration)
- Cytokines = Produced & Secreted (e.g. S-100b)