Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
50 Cards in this Set
- Front
- Back
What are Electrical synapses |
Specialized modifications of the membrane between two adjacent cells that allow a direct transfer of small molecules. Most common in Glial sections |
|
What is a Jap junction |
Electrical Synapse Small regions closely apposed cell membranes containing channels. -Permeable to ions and Small Metabolites. -Short half life |
|
Where are typical gap junctions found? |
Astrocytes, oligodenrocytes, schwann cells, ependymal cells. |
|
What do gap junctiosn participate in? |
Control of capillary beds Pathological conditions (cerebral edema) Embryonic Development - Help to define synchronous division of cells |
|
What does coupling allow for? |
Very rapid transmission of information Seen in neurons and gap junctions Olfactory and Hypothalamus |
|
What is Charcot-Marie-Tooth Disease |
Mutation in the gene for gap junctions in schwann cells Results in demyelination and slowing of conduction in peripheral axons, muscle weakness, atrophy, and sensory loss |
|
What are Chemical Synapses |
Use of a chemical substance to convey electrical activity and sometiems other information between neurons. |
|
What is Transduction |
Action Potential converted to a chemical signal Slower, less reliable, more subject to toxins than electrical but allows a much more complex system of information processing |
|
What are the three elements of Chemical synapses |
Presynaptic elelment Synaptic cleft Postsynaptic element |
|
How are chemical synapses named? |
According to the source of the pre to postsynaptic element. Ex. Axodendritic, Axosomatic |
|
What are the steps of chemical transmission at the pre-synaptic bouton? |
1. Synthesis-Secretory vesicle synthesis and loading with transmitter and thetransport to the synaptic terminal (synthesis and packaging) 2.Depolarization of the terminal by an action potential. 3. Openingof Ca++channels which triggers 4. The release of neurotransmitter into thesynaptic cleft. |
|
What are the steps of chemical transmission at the post-synaptic bouton? |
5.Neurotransmitter diffuses across the cleftand binds to and activates of apostsynaptic cell receptor (changes shape) 6.Transduction of the signal by the postsynaptic cell. 7.Pre and Post synaptic inactivation of neurotransmitter that can includereuptakeor degradation of the neurotransmitter (termination). |
|
How are Large Neurotrasmitters synthesized? |
Synthesied in the Golgi apparatus and transported via fast axoplasmic transport to the nerve terminal Released but not recyled. |
|
How are small neurotransmitters synthesized |
Undergo extensive recycling and synthesis within the pre-synaptic terminal. Sensitive to agents which can interfere with synthetic or recycling enzymes (Aceytlcholine) |
|
Describe the Depol of the terminal |
Loaded Synpatic vesicles -Chemical synapse initiated by AP and depols the pre-terminal This opens voltage channels for calcium in the pre-terminal |
|
Effect of Ca increase on transmission? |
Initiates vesicle release Fusion of the vesicle membrane with active zone of pre-terminal Release of neurotransmisster to synaptic cleft |
|
Transmission and the synaptic cleft |
After releasem NT diffuse across the synapticcleft and contract receptors on the post synaptic membrane. |
|
Receptors and their reaction to NT will |
Define the nature of the transduction in the post synaptic membrane |
|
What is a typical transduction reponse |
Opening of ion channels such as sodium to produce a depol of the post synaptic membrane. |
|
|
|
|
|
|
|
Descibe NT Reuptake? |
Mostneurotransmitters or their inactivated products are directly taken up bytransporter proteins on the presynaptic membrane, and on adjacent neuroglialcells |
|
Describe Vesicle Recycling |
Synaptic vesicle membrane is reincorporated into new synaptic vesicles. Small molecule transmitters, vesicles are reloaded within the terminal reused |
|
What is Enzmatic Inactivation |
Molecule is destroyed or modified by membrane boundenzymesaround the synaptic cleft. May be in Pre or post membrane |
|
What is Neuromodulation? |
Release of NT directly into the extracellular space: Catecholamines and neuropeptides Often in Periperies in relation to smooth vessels. |
|
How are receptor activation classified? |
–Ligated channels- open or close transmembrane pores or channels –G-proteincoupled and other second messengerreceptors –Transmembrane receptors with modifiableenzymatic activity –Ligand -dependent regulators of nucleartranscription –Sequestrationof intracellular ions (calcium in particular). |
|
What is a NT receptor agonist? |
Agents which mimic or enhance the mornal action o a NT either through action on cell receptors or other mechanisms |
|
What is a NT receptor antagonist |
Block the normal action of a NT by direct or indirect effects on the receptos |
|
What is a Ionotropic Synapse? |
includes small moleculesynapses, fast synapses, singlemessenger synapses. Activate primarily ionotropicreceptors. postsynapticmembrane opens an ion channel to depolarize or hyperpolarize the postsynapticmembraneotection:0 |
|
What is Metabotropic Synapse |
includes larger neuropeptidesynapses, slow synapses, second messenger synapses. Activate primarily metabotropicreceptors. producea second messenger molecule that acts usually through a different mechanism toproduce signal transduction. |
|
What to metabotropic receptos most often act through?
|
Guansoine nucleotide-binding protein: G-protein |
|
Describe the G-Protein |
can act as a second messenger itself in function such as the opening of ionchannels. This process can generateeither stimulatory or inhibitory signals. |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
What is determined by number of active receptors on Post synaptic cells? |
How effectively the cell can be stimulated. |
|
How is Receptor regulation accomplished |
Through metabotropic mechanisms and can include both activation and deactivation |
|
What is Denervation supersesitivity |
Neuron loses some of its afferents then increases the numbers of its receptors and becomes more sensitive to the NT involved |
|
What is Glutamate |
Most prevalent excitatory transmitter in the CNS. Derived from a-ketoglutarate Recycled by a direct transporter into presynaptic terminals for reuse and indirectly through astrocytes where it is degraded to glutamine and reconverted |
|
Describe GABA |
Primary inhibitory NT in the brain.
Synthesized by Glutamic Acid Decarboxylase |
|
Describe Glycine
|
Inhibitory NT primarily in the brainstem and SC Primarily associated with mechanisms of recurrent inhibition Part off feedback inhibitory mechanism common to motor neuron pools to limit activity |
|
Describe Acetylcholine |
Importantneurotransmitter in both the central and peripheral nervous systems with bothexcitatory and inhibitory properties with both ionotropicand metabotropic receptors |
|
Describe Catcholamines |
Bothexcitatory and inhibitory. They are synthesized from tyrosine in successivesteps to create the neurotransmitters dopamine, norepinephrine, andepinephrine |
|
Describe Serotonin |
excitatory and inhibitory-synthesized from tryptophan |