travers- neuronal structure & signalling Flashcards by asw asw

what is the only region of the brain where neurons have been shown to divide?

hippocampus

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______ are the major input processes of neurons (respond w/graded potentials)

dendrites

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the ______ of a neuron is the trigger zone for action potentials

axon hillock

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where in the neuron are vesicles stored?

axon terminal (for release into the synaptic cleft)

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which type of neuron has cell bodies outside the CNS?

afferent neurons (CBO in ganglia)

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what type of cell makes up 90% of the CNS?

glial cells

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_______ are the myelinating glia cells in the PNS

________ are the myelinating glia cells in the CNS

PNS- schwann cells

CNS- oligodendrocytes

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list the functions of Astrocytes:

Regulate extracellular fluid, e.g. remove K+ and neurotransmitters: buffering role

Provide neurons metabolically (e.g. glucose)

Surround brain capillaries: form blood brain barrier

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which myelinating glial cell can serve multiple neurons?

oligodendrocytes

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what facilitates the Movement of proteins & other material from one part of neuron to another

Microtubules (structural components of axon)

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what are the 2 forms of transport through a neuron?

Anterograde transport

Retrograde transport

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_________ transport occurs from the cell body toward the terminal

anterograde

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what type of motor protein does anterograde transport use?

kinesins

similar to myosin contractile proteins

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what motor protein does retrograde transport use?

dynein

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what is the downside to retrograde transport in neurons?

it can carry viruses (herpes, rabies, polio) toward the neuron body

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what virus remains latent in trigeminal ganglion?

Herpes simplex virus type 1

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During latency, the herpes simplex virus (type 1) is transcriptionally quiet except for a _________

latency associated transcript (LAT)

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characteristics of CNS damage and nerve regeneration:

Damaged CNS neurons do not regenerate

Axons “sprout” but axons do not reach targets

Scar formation prevents surviving axons from reaching targets

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when a CNS neuron is damaged, what substance do the astrocytes produce? what does this cause?

Astrocytes make chondroitin sulfate proteoglycans that inhibit neuron growth

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what determines the recovery of a PNS injury?

severity of the injury

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anterograde degeneration due to severe trauma is also known as “________” degeneration. What does this do to the neuron?

Wallerian degeneration

leads to neuron cell death, transganglionic degradation, and transynaptic degradation

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what is the nerve response to a less severe injury?

terminal degradation and Chromatolysis

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what is Chromatolysis?

the degradation of nissl bodies (granular bodies of rough ER)

associated with protein synthesis
cell body swells, eccentric nucleus

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after injury, schwann cells proliferate and produce _______ for substrate for regenerating axons

laminin

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schwann cells produce ________ which is transported to the ganglion cell body

NGF (neural growth factors)

what is the role of NGF in neuron regeneration?

NGF regulates gene expression and promotes sprouting

the release of NGF will ultimately lead to ________ sprouting

collateral

what explains Increased Crossed-midline Sensitivity after the removal of the trigeminal nerve?

collateral sprouting

there is a negative correlation between ______ and the recovery and function of nerve damage

age

what is a synapse?

An anatomically specialized junction between a neuron and another cell at which the electrical activity of the presynaptic neuron influences the electrical activity in the postsynaptic cell

what are the types of synapses?

- Chemical vs electrical (also called gap junctions, rare in CNS) - Excitatory vs inhibitory

name the 3 types of chemical synapses

Axo-somatic Axodendritic Axo-axonic

what is the difference between temporal summation and spatial summation?

Temporal summation: adding together of PSP’s from one synaptic contact (over time) Spatial summation: adding together of PSP’s produced by different synapses

a classical neurotransmitter can:

Functions in rapid communication (msec) Act on postsynaptic cell to produce EPSP or IPSP

____________ are often co-released with neurotransmitters

neuromodulators

what is the role of neuromodulators?

May act postsynaptically to amplify or dampen on-going synaptic activity May act on pre-synaptic cell to alter synthesis, release, uptake or metabolism of neurotransmitters Actions can involve changes in DNA/protein synthesis or enzyme activity: can thus be much slower in action (min – days)

how is acetylcholine synthesized?

Synthesized from choline and acetyl Co-enzyme A by choline acetyltransferase in synaptic terminal

examples of neurons that release ACh:

Motor neurons Neurons in nucleus basalis and pons All preganglionic neurons (sympathetic & parasympathetic) All postganglionic parasympathetic neurons

what are the 2 main regions of the CNS that release ACh? what is the role of these 2 regions?

- Basal forebrain (cognitive function) | - Pontine nuclei (sleep regulation)

what are the types of ACh receptors? where are they found?

- Muscarinic receptors: Mostly found in CNS | - Nicotinic receptors: Relatively few in central nervous system

which ACh receptor triggers G protein that open or close ion channels?

Muscarinic receptors

how do nicotinic receptors cause changes in the postsynaptic cell?

ACh binding opens ion channel within receptor | Channel permeable to Na+ and K+, therefore depolarizing

_________ is an autoimmune disorder in which individual makes antibodies to nicotinic receptors

Myasthenia gravis

how is myasthenia gravis treated?

Treated with acetylcholinisterase inhibitors

which ACh receptor disorder is the most common form of dementia?

Alzheimers disease

what are Biogenic Amines synthesized from?

amino acids

what are the 3 bionegic amines that are classified as Catecholamines? what amino acid are they produced from?

dopamine, norepinephrine, epinephrine -Synthesized from the amino acid tyrosine

describe the life cycle of catecholamines:

1) Synthesis- Presynaptic terminal - Stored in vesicles 2) Release- Ca++ dependent 3) Termination of action a. presynaptic neuron re-uptake b. degradation

______ is a common molecule that can breakdown catecholamines

Monoamine oxidase | MAO

T/F: Receptors for catecholamines are almost exclusively G-protein coupled receptors

true

Catecholamines are associated with what neurological diseases?

Parkinsons’s disease, depression, schizophrenia

what are the 2 structures of the CNS that produce dopamine?

Ventral tegmental area Substantia nigra

the ventral tegmental area associated with ________ and _________

reward and addiction

the substantia nigra is associated with the ______ system

motor

there are ______ dopamine receptor subtypes. All are G-protein coupled

five

what is the main effect from activation of D1 (dopamine 1) receptors? D2?

D1: activate adenylate cyclase D2: inhibit adenylate cyclase (leading to hyperpolarization)

what condition is often associated with the D2 receptors of patients receiving dopamine blocking drugs?

Tardive Dyskinesia

T/F: Norepinerphrine requires presence of additional enzymes for synthesis from Epinephrine

FALSE- Epinerphrine requires presence of additional enzymes for synthesis from norepinephrine

NE neurons include:

Sympathetic postganglionic neurons (and some CNS)

Epinephrin neurons include:

Adrenal gland (medulla) as circulating hormone (not much in CNS)

catacholamine and other biogenic amine receptors are almost all _________ coupled

g-protein

what are the 2 different types of alpha NE receptors? what is their function?

α1 (intracellular release Ca++): excitatory α2 inhibitory via opening K+ channels or blocking Ca

how do beta NE receptors function?

beta receptors: (ß1, ß2 ,ß3): open Ca++ channels

NE can have very different effect on tissue depending on what?

the receptor type (alpha 1 or 2, beta)

what regions of the CNS use Norepinephrin?

Locus ceruleus- attention/sleep Other brainstem groups- Autonomic & homeostatic functions

Serotonin is involved with which CNS structures? what is the role of these structures?

Rostal raphe nuclei -Sleep, mood, homeostatic function Caudal raphe nuclei -Sensori-motor function

T/F: serotonin is involved in many functions ranging from sensorimotor systems to cognitive function

true

Histamine is derived from amino acid ______

Histidine

histamine is involved in the control of _____________ cycles in the CNS

sleep-wakefulness

what are the "Excitatory Amino Acids"?

glutamate & aspartate Glutamate: most common excitatory neurotransmitter

Glutamate & aspartate bind to several classes of _________receptors

ionotropic

Amino acid neurotransmitter receptors are also a class of _________ receptors, which are g-protien coupled

metabotropic receptors

the N-methyl-D-aspartate (NMDA) receptors are the Synaptic mechanism of _______________

Long term potentiation -functions that last (memory formation, chronic pain)

what factors promote long term potentiation?

- Phosphorylation of NMDA receptor (removal of Mg+ block) | - Calcium entry into cell via NMDA receptor

what is the Major inhibitory neurotransmitter in CNS?

GABA (gamma-amminobutyric acid)

GABA is a modified form of what?

Glutamate

What type of receptor is GABAa? what effect does it have? what about GABAb?

GABAA : ionotropic receptor ----opens Cl- channel GABAB receptor: metabotropic receptor ----opens K+ channels

what disease is linked to a GABA deficiency?

Huntington chorea

characteristics of glycine:

Amino Acid neurotransmitter A) Inhibitory neurotransmitter (mostly spinal cord) B) Receptor opens Cl- channels C) Blocked by strychnine

________ function as neuromodulators | hint: they are formed by the linking of 2 base units

peptides

what is the only gaseous neurotransmitter? what are its effects?

Nitric oxide (NO) Can modulate neurotransmitter release, e.g. glutamate & GABA

the neurotransmitter ______ is usually excitatory, and is co-released with other classical neurotransmitters

ATP

how does calcium entry due to NDMA receptors lead to long term potentiation?

Phosphorylation of AMPA receptors Increase number of AMPA receptors Synthesis of retrograde messenger nitric oxide (NO)