CNS 2 Flashcards
1
Q
Neuroglia in CNS
A
- astrocytes
- oligodendroglia
- microglia (latent phagocytes)
- ependymal cells (line ventricles/CSF production)
2
Q
Neuroglia in PNS
A
- Schwann cells (cover/myelenate the axon)
- satellite cells (cover the cell body)
3
Q
pyramidal cells
A
- a type of multipolar neuron of cerebral cortex classified by dendrites
- makes up about 75% of neurons
- Primary excitation unit of frontal cortex
- Excited by: glutamate and aspartate
- Inhibited by: GABAA
4
Q
Stellate or granule cells
A
- neuron type in cerebral cortex
- makes up about 25%
- excitatory amino
- acid (glutamate or aspartate)
-
most are inhibitory
- y-aminobutyric acid (GABA) transmitter
5
Q
Myelination
A
- allows for faster conduction
- increases the effective membrane resistance (by decreasing the amt of Na that leaks out)
- decreases the capacitance
- restricts action potential generation to only the nodes of Ranvier
6
Q
capacitance
A
the ability of a system to store an electric charge
7
Q
functional benefits of myelination
A
- efficiency
- fast reflexes
- complex mental processing
- lower metabolic requirements
8
Q
Synaptic Signaling
A
- classic neuron-neuron junction
- electrical (gap junctions)
- chemical (neurotransmitter)
- Neuron- Glial
- Ligands to G protein receptors in glial cells
- Extra-synaptic
- Neurotransmitters sneak out and hit other axons
9
Q
electrical synapses/ gap junctions
A
- low resistance pathway that allows current to flow from one cell to another
- allows exchange of small molecules between cells
- bidirectional
- Gap junctions regulated by:
- voltage, intracellular pH, Ca, and G protein coupled receptors
10
Q
SNARE
A
- the protein that mediates vessicle fusion
- brings the vessicle to the terminal edge of the axon
11
Q
astrocytes
A
- BBB
- K+ uptake
- SVR of small vessels
- ACh recycling
- communication
12
Q
oligodendroglia
A
myelination of the CNS
(multiple different axons)
13
Q
microglia
A
- phagocytic cells of the CNS
- since Ab don’t cross BBB
14
Q
Ependymal
A
- CSF production
- line the ventricles
15
Q
bipolar neurons
A
- type of neuron classified by number of neurites
- two processes
- axon and dendrite
- retina/olfactory epithelium only–not common
16
Q
pseudo unipolar neurons
A
- type of neuron classified by number of neurites
- sensory only
- One axon, two branches
- branches serve the function of both axon and dendrite
- one branch in CNS, one in PNS
- cell body in the dorsal root ganglion
17
Q
multipolar neurons
A
- Type of neuron classified by number of neurites
- by far most common
- one axon and multiple dendrite
18
Q
stellate cells
A
- type of neuron classified by dendrites
- star shaped
- 25% of CNS
- Ex: inhibitory, GABA or some excitatory, aspartate or glutamate
19
Q
v-SNARES
A
are incorporated into the membrane of the transport vesicles
20
Q
t-SNARES
A
associated with the nerve terminal membrane
21
Q
types of SNARE proteins
A
synaptobrevin
syntaxin
SNAP-25
22
Q
synaptotagmin
A
- binds to the Ca++ and SNARE complex and allows for exocytosis to occur
23
Q
4 mechanisms of Ca++ entry and exit
A
- Ca++ pump
- Ligand gated Ca++ channel
- Voltage gated Ca++ channel
- Na+/Ca++ exchanger
***remember Ca++ concentration gradients are HUGE!!
24
Q
criteria for a neurotransmitter
A
- must be present in presynaptic terminal
- cell must be able to synthesize the substance
- must be released upon depolarization of presynaptic membrane
- there must be a specific receptor on the postsynaptic membrane (some go to extrasynaptic locations)
***over 100 neurotransmitters currently identified
25
Class 1 Neurotransmitter
Acetylcholine
26
Class II Neurotransmitters
Biogenic Amines
1. Norepinephrine
2. Epinephrine
3. Dopamine
4. Serotonin
5. Histamine
27
Class III Neuro transmitters
Amino Acids
1. Gamma-aminobutyric acid (GABA)
2. Glycine
3. Glutamate
4. Aspartate
28
Class IV Neurotransmitters
1. Neuropeptides/Peptide transmitters
1. i.e. hormones, Angiotensin II, Insulin, Oxytosin
29
Gaseous Neurotransmitters
* Are not released from "vesicles"
* able to diffuse out at any point and may travel far before encountering receptor
* Ex: NO, CO
30
Glutamine-Glutimate cycle
aka
Glutamate Recycling
1. Axon terminal is depolarized and glutamate is released by vesical out of axon terminal
2. Glutamate hits receptors on other side of synaptic cleft. Once it is released or if it never bound, glutamate gets taken up by glial cells and converted back into glutamine.
3. Glutamine gets released by the glial cells and it goes back into the axon.
4. Glutaminase turns the glutamine into glutamate and it gets repackaged into vesicle and ready for next release.
31
Acetylcholine Recycling
1. Acetylcholine is made from choline and Acetyl CoA
2. after being released from Axon terminal, acetylcholine is quickly broken down by acetylcholinesterase.
3. Choline is transported back into the axon terminal and is used to make more ACh.
32
Ion current equation
Ix = gx\*(Vm-Ex)
Ix = total current
gx = conductance of individual ion channel
Vm = resting membrane potential
Ex = Nerst potential for that ion
\*\*Ion current flow direction depends on electrochemical gradients of permeant ions
33
MEPP
* Miniature end plate and potential
* small \<0.5 mV depolarizations of postsynaptic membrane
* reflect spontaneous release of a single synaptic vesicle
* too small to reach threshold so no action potential occurs
34
EPSP
* Excitatory response
* increased Na+ influx
* decreased Cl- influx or K+ efflux
* change in receptor expression or enzymatic/metabolic activity
* lasts about 15 milliseconds, must have multiple within this time for an AP to occur
35
IPSP
* Inhibitory response
* Increased Cl- influx or K+ efflux
* pre synaptic
* post synaptic
* change in receptor expression or enzymatic metabolic activity
36
changes in pH affect on synaptic transmission
* alkalosis- greatly increases neuronal excitability
* acidosis- greatly depresses neuronal activity
* hypoxia- severely decreases neuronal excitability
37
A alpha sensory
* large, myelinated, fast
* primary golgi
