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CELL 302 > Lecture C5 + C6 + C7 > Flashcards

Lecture C5 + C6 + C7 Flashcards

1
Q

Neurons have three main parts : ______

A

-cell body (soma): has nucleus and most of the organelles
-dendrites: many process that receive stimuli at synapses
-axon: single long process that generate and conduct nerve impulses to other cells

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2
Q

Most cell bodies are in contact with many nerve endings conveying _____ stimuli from other neurons.

A

-excitatory or inhibitory

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3
Q

Due to concentrated rough ER and polysomes, cell bodies of neurons are _____ and are distinguished as ______

A

-basophilic (purple colour)
-Nissl substance/Nissl bodies

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4
Q

basophilic dye is ____ & stains ____

A

-purple/basic (cationic)
-anionic stuff

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5
Q

dendrites are the main _____ on neurons

A

-signal reception and processing sites

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6
Q

In the CNS most synapses on dendrites occur on ______, which are dynamic ______ along the small dendritic branches. Changes in them are important for _____

A

-dendritic spines
-membrane protrusions
-neural plasticity

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7
Q

neurons are classified based on _____

A

morphology

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8
Q

Multipolar neurons descr

A

one axon and two or more dendrites. They are the most common.

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9
Q

Bipolar neurons descr. + example

A

-one dendrite and one axon
-the sensory neurons of the retina, the olfactory epithelium, and the inner ear

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10
Q

Unipolar/pseudounipolar neurons descr. + example

A

-a single process that bifurcates close to the soma, with the longer
branch extending to a peripheral ending and the other toward the CNS (1 axon)
-These include all other sensory neurons

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11
Q

Anaxonic neurons descr. + function

A

-many dendrites but no axon
-do not produce action potentials but regulate electrical changes of adjacent neurons

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12
Q

Sensory neurons are _____, receiving stimuli from receptors throughout the body. Most sensory neurons are _____

A

-afferent
-pseudounipolar

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13
Q

Motor neurons are _____, sending impulses to effector organs such as muscle fibers and glands.

A

-efferent

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14
Q

Interneurons are the ones in between _______. They connect ______

A

-motor and sensory neurons
-spinal motor and sensory neurons.

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15
Q

In ALS, there is degeneration of ______

A

motor neurons

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16
Q

Neurons in your brain are classified based on ______ (2)

A

neurotransmitter and effect on target neurons

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17
Q

A neuron can be classified based on the neurotransmitter that it uses to send its messages (ex. ________ (3))

A

-glutamatergic neurons, GABAergic neurons, cholinergic neurons

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18
Q

Sometimes neurons are classified based on its effect on target neurons: excitatory neurons are mostly ______ and inhibitory
neurons are ______

A

-CNS glutamatergic neurons
-adult brain GABAergic neurons

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19
Q

CNS glutamatergic neurons are excitatory by ______

A

releasing glutamate which stimulates Na+ entry into post-synaptic neuron leading to depolarization

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20
Q

Adult brain GABAergic neurons are inhibitory by ______

A

releasing GABA which stimulates Cl- entry into post-synaptic neuron leading to hyperpolarization

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21
Q

The plasma membrane of the axon is often called the _____ and its contents are known as _____. Axons originate from the _____

A

-axolemma
-axoplasm
-axon hillock

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22
Q

Beyond the axon hillock is the _____, where ______ that generate the action potential are located.

A

-axon initial segment
-concentrated ion channels

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23
Q

Membrane potential: Cells at rest normally have excess _____ on the outside and _____ on the inside of the cell. The resulting electrical potential is called the _____

A

-positive charge (Na+ ions)
-negative charge (K+ ions)
-resting membrane potential (-70mV)

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24
Q

Action potential steps

A

1) synaptic input from dendrites -> local changes in membrane potential of varying magnitude (stimulus opens Na+ channels, depolarizing membrane)
2) If threshold is reached (-50mV), it triggers action potential
3) most of Na+ channels are open but K+ is closed, Na+ influx makes inside more positive than outside (happens in AIS first
4) Na+ channel close, K+ channels open and K+ flux in (cell becomes more negative) - happens in AIS first
5) K+ remain open -> hyperpolarization; K+ channel close -> membrane returns to resting state - happens in AIS first
6) depolarization spreads to regions adjacent to AIS until they depolarize too and action potential propagates (in nodes of ranvier if myelinated)

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25
Nerve cells communicate with each other and other cells through two types of synapses: ______
-electrical synapse: one neuron (presynaptic) is connected to second neuron (postsynaptic) via gap junctions -> ions move through gap junctions (connexon made from connexin proteins) -> no delay in transmission -chemical synapse: presynaptic and postsynaptic neurons are not connected by gap junctions but separated by synaptic cleft; signal is sent from pre to postsynaptic neuron by chemical messanger/neurotransmitter
26
Bacteriorhodopsin is a ______ in the plasma membrane of archaea. It uses energy from ______ to drive active transport of protons and create an ________
-small integral membrane protein -photons -electrochemical proton gradient that powers an ATP synthase
27
Channelrhodopsins are ______
rhodopsins that have molecule retinal and under light, depolarize (moves K+ out and Na+ in)
28
Optogenetics is a method that uses light to ______
- modulate molecular events in a targeted manner in living cells or organisms
29
Optogenetics relies on the use of genetically-encoded proteins that ______
change conformation in the presence of light to alter cell behaviour, (ex. by changing the membrane voltage potential of excitable cells) -uses channelrhodopsins
30
Types of functions of Glia (6)
-Astrocyte (Astroglia): physical and nutritional support for neurons -Oligodendrocyte: insulation (myelin) of neurons in the central nervous system -Microglia: digest parts of dead neurons -Ependymal cells: Aid production and movement of CSF -Satellite cells: Physical support to neurons in the peripheral nervous system -Schwann Cells: insulation (myelin) of neurons in the peripheral nervous system
31
Myelin is ____ and does what?
-compacted layers of cell membrane that wraps around axons -electrically insulates the axon and facilitates rapid transmission of nerve impulses
32
Oligodendrocytes are the predominant glial cells in _____, which is white because of the ______ in myelin sheaths
-white matter -lipid concentrated
33
Gaps in the myelin sheath are called _____, which contain clustered ______. Action potential is regenerated at ______
-nodes of Ranvier -voltage gated Na+ and K+ channels -nodes of Ranvier
34
Saltatory conduction (def.)
action potential jumps from node to node along the axon
35
Saltatory conduction mechanism
1) influx of Na+ associated with action potential results in depolarization at one node 2) depoloraization moves rapidly down axon because of excess Na+ ions, cannot move out across myelinated surface; build up of Na+ at next node = depolarization 3) depolarization -> action potential at next node; action potential jumps from node to node = faster
36
Multiple sclerosis is defined as ____
an autoimmune demyelinating neurodegenrative disease; demyelination leads to neuronal damage/neuron death
37
Astrocytes have a large number of ______. Proximal regions of the astrocytic processes are reinforced with ______
-long radiating, branching processes -bundles of intermediate filaments made of glial fibrillary acid protein (GFAP)
38
Astrocytes form part of the _____ and help regulate _____
-blood-brain barrier (BBB) -entry of molecules and ions from blood into CNS tissue
39
General functions of astrocytes (5)
1) regulating formation, function and plasticity of synapses 2) part of BBB 3) metabolic support to neurons 4) guiding and physically supporting movement and location of differentiating neurons during CNS development 5) proliferation after CNS injury to form astrocytic glial scar
40
The glutamate-glutamine cycle refers to the ______
-compartmentation of glutamate and glutamine between neurons and astrocytes
41
During glutamatergic neurotransmission, neurons release ____ into the extracellular space; the astrocyte glial cells do what?
-glutamate -their glutamate transporters rapidly remove the released glutamate (return to neuron)
42
____ is the main source of energy for the brain. Its use correlates with ______
-Glucose -neuronal activity
43
Astrocytes store glucose in the form of ____ and contribute to fueling neurons by supplying ____ in certain situations such as _____. This process is called _____
-glycogen -lactate -hypoglycemia and ischemia (restricted blood flow) -Astrocyte-neuron lactate shuttle
44
Astrocytes prune neuronal synapses by ______
recognizing eat-me signals in silent synapses and phagocytosing them through MEGF10 and MERTK phagocytic pathways
45
Astrocytes surround the BBB with their ______.
-astrocytic perivascular endfeet
46
Astrocytes can upregulate many BBB features, leading to ______, the expression and ______, and ______
-tighter tight junctions (physical barrier) -polarized localization of transporters (transport barrier) -specialized enzyme systems (metabolic barrier)
47
Schwann cells are the counterparts to _______. They form the myelin sheath of the ____. Unlike an oligodendrocyte, a Schwann cell forms myelin around a ______
-oligodendrocytes of the CNS -PNS -portion of only one axon.
48
Schwann cells form myelin on axons of _____ in the PNS (still saltatory conduction). Schwann cells do not form myelin wrappings around _____. Their impulse conduction is not ______
-large diameter -small axons but simply encloses them -saltatory and is much slower than that of myelinated axons
49
Guillain–Barré syndrome (GBS) is an ______ presenting typically with _____
-acute inflammatory immunemediated polyneuropathy -tingling, progressive weakness, autonomic dysfunction and pain
50
In some GBS cases, ______ specifically takes place at the myelin sheath and related Schwann-cell components. Outbreaks of GBS have been linked to certain ______
-immune injury -bacterial and viral infections
51
Early neural development summary
-invagination of ectoderm (outermost layer) -> neural tube -anterior part of the neural tube expands and forms forebrain (prosencephalon), midbrain (mesencephalon), hindbrain (rhombencephalon), and spinal cord -prosencephalon becomes telencephalon (future cerebral cortex and basal ganglia), diencephalon (future thalamus and hypothalamus),
52
Cortical excitatory projection neurons are generated in an _____. They arise from the _____ and migrate ______.
-inside-out manner -ventricular/subventricular zone -radially
53
Inhibitory interneurons arise from the _____ and migrate _____.
-ganglionic eminence -tangentially
54
The normal adult cortical plate is divided into layers _____, numbered from ______. Projection neurons in the cortical plate are layered with _______
- I through VI - outside (pial surface) to inside (ventricular surface) -oldest neurons below and youngest ones above
55
During the first trimester, neuroepithelium cells undergo ______
-symmetric division to expand the progenitor pool
56
Symmetric vs asymmetric cell division
-Symmetric: cell fate determining factors are divided evenly between daughter cells (identical cell fates) -Asymmetric: cell fate factors divided unequally between daughter cells (different cell fates)
57
Lateral expansion increases in _____ . Radial growth increases _____.
-surface area via symmetric, proliferative divisions -cortical thickness via asymmetric neurogenic/differentiative divisions
58
Neuroepithelial cells are ____ shape and anchored to _____ extracellular matrix. These cells have ____ cilium. _____ are localized near the cilium and ______ towards the pia (____). During interkinetic nuclear migration, the nucleus moves along the ______
-radial -pial and ventricular -ventricular (apical) -Centrosomes -microtubule plus end -top -apicobasal axis of the cell in concert with the cell cycle (G1,S moves to pial surface with KIF1A, G2 and mitosis to ventricular surface with dynein)
59
Centrosomes remain at the ______ throughout the cell cycle. Microtubules radiate from the _____ and with plus-ends towards the _____. Neuroepithelial cells migrate _____ during the G2 phase of the cell cycle and undergo mitosis only when the nucleus is at the ______
-ventricular surface -centrosome region -pial surface of the brain -apically -apical surface (ventricular)
60
Cytoplasmic dynein transports the nucleus along the microtubules ______. After cell division, the plus-end directed microtubule motor ____ acts to moves the nucleus slowly and uniformly toward the ____ until the cell enters ____
-apically toward the ventricular surface for cell division -KIF1A - pial surface of the brain (basal) -Sphase
61
NE cells elongate and convert into _____, a type of neural progenitor cell. ______ are generated from progenitors and they migrate radially along the radial glia scaffold. They establish the cortical plate in an inside out manner, with the earliest generated neurons forming the ______ while the youngest neurons ______
-radial glia cells -Excitatory cortical pyramidal neurons -deeper cortical layers -contribute to the superficial layers
62
Nucleokinesis describes the process by which ______. It involves first the extension of a ______. ______ then moves into the neurite. The nucleus follows through microtubule and ______.The cycle then repeats with neurite extension.
-neuronal cells migrate out of the neuroepithelium to populate the cortex -leading process or neurite -The microtubule organizing center (MTOC, aka. The centrosome) -dynein dependent nuclear movement
63
______ complexes function as outer nuclear membrane (ONM) adaptors for cytoplasmic dynein. KASH domain proteins are tethered in the _____. The SUN domain proteins in turn are thought to be anchored to the ______. Dynein engages with microtubules that have ______, and this results in directed nuclear migration.
-KASH domain proteins of LINC (linker of the nucleoskeleton and cytoskeleton) -ONM via interactions with SUN domain proteins of the inner nuclear membrane (INM) -nuclear lamina -minus ends orientated at the MTOC
64
neurogenesis (def.)
formation of new neurons; used to be thought that it only occurs before and immediately after birth
65
A chemical “trick” to study adult neurogenesis in rodents
-BrdU is incorporated in the DNA of proliferating neural stem and progenitor cells -The presence of BrdU or its derivatives can be detected using antibody staining or chemical reactions. -BrdU labels proliferating cells at the time of injection but it will also be “passed on” to their progenies such as neurons.
66
Adult neurogenesis mainly occur in the ______ in mice.
- hippocampus and the olfactory bulb
67
Nuclear bomb tests revealed active neurogenesis in adult human brain
-radioactive carbon 14C incorporated into new neurons during neurogenesis
68
Human hippocampus generate _____ at a fairly steady rate well into old age. A majority of dentate gyrus (______) neurons are subject to change. About _____ in the adult human dentate gyrus, similar to the levels found in middle aged rodents.
-new neurons -a special region in the hippocampus - 700 neurons are added daily
69
technical issues with studying neurogenesis in humans
-No unique marker for neurogenesis -Postmortem nature of the samples used -Incompatibility between the particular tissue processing methodologies required to perform certain studies
70
why adult neurogenesis is important to study?
-Strategies for brain repair -A major hypothesis claims that anti-depressants work through enhancing adult neurogenesis -deficits in adult neurogenesis contribute to Alzheimer’s disease pathogenesis
71
______ is impaired in patients with Alzheimer’s disease
-Adult hippocampal neurogenesis

CELL 302 (18 decks)

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