Neurons and Glia Flashcards
Type of neuron with single process with peripheral branch and central branch, found in sensory glia
Unipolar (pseudounipolar)
End feet of these wrap blood vessels as part of the BBB
Astrocytes
These cells are about .01-.05 mm in diameter and couldn’t be studied without microscope
Neurons
When environment, learning, drug exposure can change gene regulation with changes potentially being passed to offspring
Epigenetics
Shortest of the cytoskeleton components
Microfilaments
Unique cell part to neurons with little to no RER, but has ribosomes, microRNAs, and mRNAs
Axon
Study of axonal transport that use GFP or other labeled proteins in cultured neurons, some confocal imaging in vivo preps
Imaging
Used to “fix” the brain in 19th century
Formaldehyde
Type of neuron found in sensory structures like the retina and olfactory bulb
Bipolar
In adult brain are glial cells like astrocytes in SVZ (sub ventricular zone) or oligodendrocyte precursors
Stem cells
The brain has large diversity in this 3’ part of DNA
3’ untranslated regions
What do more dendrites correlate with?
More synaptic input
The most numerous glia
Astrocytes and oligodendrocytes
Composed of two thin strands of actin polymers
Microfilaments
What do mice neurons show that human neurons may not during development?
Less changes (less CNVs)
Many of these are embedded in the membrane
Proteins
How do organelles in neurons compare to those of other cells?
Same organelles but some differences in distribution
What percentage of our 20k genes are expressed in the nervous system
70%
All pyramidal cells and some stellate cells are this
Spiny
Most neurons are these
Interneurons
Multiple layers of this are often wrapped around an axon
Myelin
These are motor neurons
Muscles
Cytoskeleton component running longitudinally close to the membrane
Microfilaments
How much of our total body ATP does the brain use?
20%
Many genes are regulated by activity in the brain, activity examples include these two
Electrical and synaptic
Some stellate cells are this
Aspinous
Two ways neurons are classified based on axon length
Golgi type I and type II (projection and local circuit)
Could have implications for neural function and disease because neurons with different genomes may have different phenotypes. Addition of deletion of gene sections
CNVs
What can change in a cell during development leading to specific sets of transcripts?
Changes in cells transcriptome
Line the ventricles (secrete CSF), direct cell migration during development
Ependymal cells
This is mediated by chemical NTs
Synaptic transmission
A type of MAPS protein found in paired helical filaments seen in AD tangles
Tau
Cytoskeleton component running axially and radially and have a +/- polarity
Microfilaments
Cells that can already be in location of need or migrate in to location of need
Microglia
These cytoplasmic structures are often associated with other proteins (MAPS)
Microtubules
Some are covered with spines and can change structure depending on type and amount of synaptic input
Dendrites
What forms the tripartate synapse?
Axon, dendrite, and astrocytes
Glioma brain tumors often due to these and are hard to remove due to many projections
Astrocytes
Cytoskeleton component running 100um in length axially
Neurofilaments
These are primary sensory neurons
Skin and retina
This organelle is about 5-10 um in size and surrounded by its own membrane
Nucleus surrounded by nuclear membrane
Are a lot of neuron genes expressed in other cells as well?
Yes
The beginning of axons with no ribosomes and little organelles. Acts as gatekeeper
Axon hillock
Cytoskeleton component 10nm in diameter known as intermediate filaments in other cells
Neurofilaments
SLIDE 69
SLIDE 69
Believed that neurites were all connected like a big net
Golgi
Study of axonal transport that used ligature to block transport to discoed flow axoplasmic transport
Accumulation - Weiss
Why aren’t Nodes of Ranvier myelinated?
VG Na+ channels are there for saltatory conduction
Neurons that extend between brain regions, have long axons, and are many pyramidal cells
Golgi type I neurons (projection)
How does speed depend on axon diameter?
Thicker = faster
These are about 350nm in length, run axially, and have +/- polarity
Microtubules
The 5nm thickness of a neuronal membrane always ions to do what?
Inside and outside ions can interact
These are stem cells that can produce other oligodendrocytes and some astrocytes
Polydendrocytes
Some of these are developed in brain development and adults over 70 have less of these
CNV postive neurons
Believed the nervous system was made up of individual cells which communicated by contact
Cajal
Stain that only allows us to count the number of neurons bc it stains cell bodies, it isn’t 3D
Nissil stain
Are all neuron genomes the same as each other?
No, they differ
Of the 70% of the 20k genes expressed in the nervous system, how many are in all cells and how many are just in the brain
8000 all and 6000 brain
Neurons that connect to neurons in the vicinity, have short axons, and are stellate neurons
Golgi type II neurons (local circuit)
Stain that labels axons, dendrites, somas, and provided a 3D structure
Golgi stain
Collection of all branches that extend from the soma
Dendritic tree
Dynein transports macromolecules in vesicles, pinocytotic, endocytotic, and old mitochondria from the end to the cell body along microtubules. 1 speed, fast 50-250mm/day
Retrograde transport
Motor proteins in anterograde and retrograde transport
Ant = kinesis Ret= dynein
Axonal transport 400-1000mm/day, carried in vesicles, membranous organelles and associated proteins
Fast axoplasmic transport
This method can be used to quantify expression of specific RNAs
Large scale RNA sequencing
Mutants of these have slower APs
Neurofilaments
Why is it difficult to quantify exact numbers of neurons and glia?
There are so many with so many connections
What type of neuron is a pyramidal cell?
Multipolar
Glia between neurons (20nm between them and neuron)
Astrocytes
Two types of neurites on a neuron
One axon and many dendrites
Releases gliotransmitters (like glutamate) that modify neuronal signaling at the Tripartate Synapse
Astrocytes
How is the nervous system actually composed?
Individual cells that communicate at synapses without contact except electrical synapses
Large amounts of ER are in neurons, also known as what?
Nissil bodies
Study of axonal transport that followed movement of labelled molecules and discovered fast axoplasmic
Pulse labeling - Grafstein
Proposed cell theory (all tissues made of cells) but wasn’t sure if it applied to the nervous system
Schwann
This dendrite structure contains actin (microfilaments) and microtubules
Spines
Where are proteins sorted to in neurons and what does the sorting?
Sorted to axons, dendrites, or soma by the Golgi
Another name for the cell body of a neuron
Soma, perikaryon
What type of neuron is a dorsal root ganglion neuron?
Unipolar
Derived mostly from hematopoietic stem cells (in the blood) and act as an immune system. Could also arise from precursor cells
Microglia
Not the terminus of an axon, but a synapse in passing a dendrite
Boutons en passant
Ends of axons that can form arbors (many short branches) with no microtubules, many synaptic vesicles, many proteins and mitochondria
Axon terminal or terminal bouton
Is there more RER in neurons or glia or other cells of the body?
More in neurons by a lot
What are microtubules made of?
Tubulin protein (they are a polymer of tubulin)
The protein composition of these 4 neuron parts differ
Soma, axon, dendrite, membrane
In peripheral nervous system, myelinates single axons (every internode region by one)
Schwann cells
Myelinating these glial cells continue long after birth
Oligodnedrocytes and Schwann cells
What is wrong with the normal color of the brain for studying it?
Cream colored, cant see cells
Walked down cell body to end on microtubules by kinesis that uses ATP. Has 2 different speeds
Anterograde transport
These are 1 um to 25 um in diameter or 1mm in squid
Axons
These are often found under dendritic spines
Polyribosomes and mRNA
Cytoskeleton component often seen at synaptic terminals and dendritic spines (transport)
Microfilaments
Neurons contain many of these organelles
Mitochondria
In brain and spinal cord, myelinate several axons
Oligodendrocytes
One of several methods used to identify unique gene expression in different brains or in different regions of the same brain
DNA microarrays (well plate with green or red to represent more gene expression in one or yellow to represent equal)
What is tubulin?
A protein that can add or remove tubulins from itself to lengthen or shorten and makes up microtubules
These can be regenerated if injured bc some act as stem cells
Myelinating glia (oligo and Schwann)
These structures of the cytoskeleton are involved in long range axoplasmic transport
Microtubules
Machine that makes thin slices of the brain so it can be studied
Microtone
Many drugs and chemicals act here and malfunctions are responsible for many mental disorders
Synapse
More of these glia are in humans than rats and they are larger and more ramified (more projections)
Astrocytes
How many NTs are there?
More than 100
After axons cut, death distal to injury was an early clue that transport occurs (anterograde degeneration)
Wallerian degeneration
Is actin static?
No, they can lengthen or shorten
Remove debris (phagocytosis), release cytokines, may be activated in response to stroke or brain trauma, may also be involved in pruning or reigning circuits
Microglia
Contain microtubules, microfilaments, and some neurofilaments
Dendrites
Has less of the brain mass but the majority of neurons
Cerebellum
What do different type so neurons express?
Specific sets of transcripts
This organelle is widespread in the cytoplasm and presynaptic region (ends of axons)
Mitochondria
These can be 1mm or over a meter long
Axons
Contain NT receptors and use NTs (glia)
Astrocytes
Stain that stains all parts of a neuron but not all neurons
Golgi stain
What may account for why some transport is slower than others?
Fast = stays on whole time slow = hopping on and off
What are two types of CNVs?
Aneuploid (rare) and subchromosomal
Their size allows them to interact with around 2 million neurons
Astrocytes
This is the same in neurons as many cells and about 20 um in size
Soma
13-41% of neurons have at least one of these
Megabase-scale de novo CNV
Cytoskeleton component that is space filling but needed for fast APs
Neurofilaments
This cytoskeleton component can go to the end of an axon while this one cant
Microfilaments can and microtubules cant
Neuron with a pyramid shape of dendrites
Pyramidal neuron
Relatively large structure (20nm diameter) in the cytoskeleton
Microtubules
Axonal transport 1-10mm/day for proteins of the cytoplasm (cytosolic proteins)
Slow axoplasmic transport
This transport can be used to trace synaptic connections
Retrograde
Three ways neurons are classified based on connectivity
Primary sensory, motor, and interneurons
What are Nissil bodies also known as?
Endoplasmic reticulum
What do gliotransmitters do and what releases them?
Released by astrocytes in response to NTs and signal back to neurons and influence signaling at one or sometimes many synapses
Where are there more neurons?
More in cerebellum than cortex
Type of neuron with many dendrites, a single axon, and most neurons are this type
Multipolar
Stain that labels nuclei of all cells and also RER of neurons
Nissil stain
Does translation occur in axons?
Yes, in mature and developing axons
Two classes of dendritic structure in the cerebral cortex
Pyramidal and stellate
This type of transcriptional control is frequent in neurons which leads to lots of proteins from the same gene
Alternative splicing
Regulate contents of extracellular space, remove NTs from synaptic cleft, regulate extracellular ion levels, can divide and are the source of the majority of brain tumors
Astrocytes
These form branches or collaterals (some can be recurrent - synapsing on own dendrite)
Axons
Covered with 1000s of synapses coming in all shapes and sizes
Dendrites
Cytoskeleton component that helps to maintain neuronal shape, as a result tangles in AD
Neurofilaments
This type of control is more complex in neurons than other cells
Transcriptional control
Cytoskeleton component with no polarity and are not transport tracks
Neurofilaments
What type of neuron is a retinal bipolar cell?
Bipolar cell
How did we discover the existence of synapses?
Electron microscopes
What are features of neuron cells that allow them to have more complex transcriptional control?
Complex 5’ and 3’ ends and lots of untranslated regions allowing for alternative splicing
Are there more neurons or glia?
About equal. 85 billion each
Cytoskeleton component 5nm thick and numerous in neurites
Microfilaments
Gap between axon and dendrite
Synaptic cleft
States the nervous system is made up of individual cells, as is the rest of the body
The neuron doctrine
What are the long range and short range transport tracks?
Long - microtubules
short - microfilaments
Cytoskeleton component involved in short range transport
Microfilaments
