| Term | Definition |
|---|
| electrical synaptic transmission: | carried through gap junctions |
| Chemical synaptic transmission: | carried through neurotransmitters |
| Kinesin transport | from soma to terminal, negative to positive |
| Dynein transport | from terminal to soma, positive to negative |
| Dendrites: | extend from the soma, are covered with thousands of synapses and membrane contains receptors to detect neurotransmitters |
| Ions are driven across the membrane at a rate proportional to what? | the difference between the membrane potential and the equilibrium potential |
| The resting membrane potential is maintained by what? | The flow of K+ current |
| Equilibrium potential is a balance between __ and __ | electrical difference, ionic concentration |
| The rising phase (depolarization) of an action potential is caused by what? | opening of voltage-gated sodium channels |
| The falling phase (hyperpolarization) of the action potential is caused by what? | opening of voltage-gated potassium channels |
| The gates that control the action potential are inactivated, closed and locked when? | the membrane acquires a positive membrane potential |
| The action potential gates are opened when? | depolarization above threshold occurs |
| Conduction velocity is influenced by what? | axon diameter |
| What does myelin not cover on an axon? | it breaks where the ions cross the membrane to generate an action potential |
| Nodes of Ranvier contains what? | voltage-gated sodium channels |
| Saltatory conduction refers to what? | the action potentials ability to "skip" down the axon |
| What are the two main types of synapses? | Electrical and chemical |
| What is a chemical synapse? | communication in which chemical neurotransmitters carry the signal from one cell to the next |
| Electrical synapses are specialized channels that occur where? | at gap junctions |
| Six connexins (proteins) combine to form what? | a connexon (channel) |
| Two connexons (one from each cell) combine to form what? | a gap junction channel |
| Gap junctions are found between __ and __ neurons of many invertebrates | sensory and motor (allows for quick escape reflex) |
| Chemical synapses are? | two cells that touch with 20-25 nm wide cleft between them containing matrix of fibrous extracellular protein |
| Presynaptic vesicles contain what? | neurotransmitters (chemicals used to communicate with the postsynaptic neuron |
| Neuromuscular junctions contain what kind of synapses? | chemical synapses |
| In neuromuscular junctions the postsynaptic membrane is called what? | the motor endplate (contains a series of shallow folds with receptors) |
| What is synaptic integration? | the process by which multiple synaptic potentials combine within one synaptic neuron |
| The amplitude of EPSP is dependent on the number of __ that are released. | vesicles |
| What is quantum referring to? | the same number of transmitter molecules that are in each vesicle released for depolarization |
| What is the "mini" or baseline of exocytosis referring to? | The miniature postsynaptic potential generated by the contents of one vesicle released without presynaptic stimulation |
| Action potential generation depends on placement of synapse and the dendrite itself because depolarization does what? | it decreases exponentially with increasing dendrite cable distance |
| IPSPs contribute to what? | shunting inhibition of action potential propagation |
| PSPs are modulated by what? | G-protein coupled receptors |
| Neurotransmitters fall into what three classes? | amino acids, amines and peptides |
| Amino acids and Amines are released from where? Peptides are released from___ | from synaptic vesicles. from secretory granules |
| Action potentials stimulate neurotransmitter release. The resulting elevation in Ca in causes what? | neurotransmitter release via exocytosis |
| Secretory granules are not released at active zones, but by ______ | exocytosis in Ca dependent manner because of build up of Ca throughout the terminal |
| Postsynaptic neurotransmitter receptors fall into what two categories? | transmitter-gated ion channels and G-protein-coupled receptors |
| What are transmitter-gated ion channels? | Pore that is open in response to neurotransmitter binding. Fast transmission |
| What are G-protein-coupled receptors? | receptor activates a G-protein that subsequently activates effector proteins. Slow, longer-lasing transmission |
| What is a postsynaptic potential (PSP)? | when the change in a membrane potential of the postsynaptic neuron (both electrical and chemical synapses) |
| What are excitatory postsynaptic potential (EPSP)? | is a depolarization- likley to stimulate an action potential (potential becomes less negative) |
| What is inhibitory postsynaptic potential? | is a hyperpolarization - unlikely to stimulate an action potential (potential becomes more negative) |
| Transmitter-gated ion channels create what when opened? | postsynaptic potentials |
| Depolarization of the postsynaptic membrane is ___ and hyperpolarization of the postsynaptic membrane is __ | excitatory, inhibitory |
| What are autoreceptors? | typically G-protein-coupled receptors that stimulate second messengers and usually inhibit neurotransmitter synthesis and release |
| What is desensitization? | this occurs when high concentrations of neurotransmitter-gated channels close (neurotransmission fails as a result) |
| What do receptor antagonists do? | they are inhibitors, bind to the receptor and block normal action of the transmitter |
| Receptor agonists do what? | Mimic the action of the transmitter |
| Immunocytochemistry can show if the molecule is stored in neurons by ___ | anatomically localize particular molecules to particular cells using antibodies for visualization |
| In situ hybridization is used for what? | to identify cells expressing a particular gene (localize mRNA using probe) |
| Studying synaptic mimicry uses microionophoresis to__ | stimulate neurotransmitter and examine microelectrode records of the effect |
| One neurotransmitter can bind to many different receptors. Each of the different receptors is called what? | a receptor subtype |
| Neuropharmacological analysis classifies receptor subtypes by what? | the receptors response to drugs |
| Exocytosis of synaptic vesicles from the active zone of presynaptic memebrane is dependent on what? | opening of voltage-gated calcium channels |
| Opening of transmitter-gated sodium channels in the postsynaptic membrane generates what? | excitatory postsynaptic potential or EPSP |
| Opening of transmitter -gated chloride channels in the postsynaptic memebrane generates what? | inhibitory postsynaptic potential or IPSP |
| Transmitter release requires what to occur? | the entry of Ca2+ into the axon terminal |
| What is unusual about endocannabinoids or endogenous cannabinoids? | they are retrograde messengers by which postsynaptic neurons act on presynaptic terminals |
| What was Dale's principle? | neurons release only one class of neurotransmitter |
| What is the "off switch" for acetylcholine stimulation of postsynaptic neurons? | Acetylchoine is degraded by acetylcholinesterase in the synaptic cleft. |
| How are peptide neurotransmitters synthesized? | the long polypeptide synthesized in rER and cleaved into an active neurotransmitter in the Glogi apparatus |
| Secretory granules containing neurotransmitter peptides are released from where? | the golgi apparatus and transported to the axon terminal by kinesin along microtubules |
| Depolarization of terminal membrane causes voltage-gated ___ channels in the active zone to open. The resulting elevation causes what? | Ca2+, it causes neurotransmitter release via exocytosis |
| Transmitter-gated ion channels create what when opened? | postsynaptic potentials |
| Autoreceptors are what? and do what? | typically G-protein-coupled receptors that stimulate second messengers and usually inhibit neurotransmitter synthesis and release |
| Depolarization ___ ___ with increasing dendrite cable distance | decreases exponentially |
| What are GABA and glycine? | they are inhibitory neurotransmitters |
| G-protein coupled receptors in the postsynaptic membrane do not directly generate EPSPs or IPSPs, but can do what? | modulate the PSPs of transmitter-gated ion channels and second messengers open/ close ion channels |
| Norepinephrine modulates the response of what? | excitatory transmitters |
| What criteria qualifies a chemical as a neurotransmitter? | it must be synthesized and stored in presynaptic neurons, it must be released from presynaptic axon terminal upon stimulation and must produce a postsynaptic response |
| What are the three approaches used to identify the different receptor subtypes for a neurotransmitter system? | Neuropharmacological analysis, ligand-binding methods and molecular analysis |
| What violates Dale's principle? | peptide-containing neurons, co-transmitters |
| What is ChAT? | It is choline acetyltransferase, the enzyme that synthesizes ACh. made in the soma and transported to the axon terminal |
| How are actions of catecholamines terminated? | by selective uptake into presynaptic terminals by Na+ dependent transporters, reloaded into synaptic vesicles or degraded by MAO |
| What is serotonin derived from? and what is it aka? | trytophan and 5-HT |
| How is serotonin removed from the synaptic cleft? | taken up by presynaptic neurons via specific transporters, reloaded into synaptic vesicles or degraded by MAO |
| Amino acidergic neurons use amino acid transmitters such as __, ___ and ___. | glutamate, glycine and GABA these are all found in most CNS neurons |
| What is found in all neurons because they are used to make proteins? | glutamate and glycine |
| What kind of neurotransmitter is glutamate? | it is a major excitatory neurotransmitter |
| What kind of neurotransmitter is GABA? | It is a major inhibitory neurotransmitter |
| What are some of the unusual qualities about endocannabinoids? | they are not packaged in vesicles like other neurotransmitters, they are synthesized rapidly on demand, they are small and membrane permeable and bind selectively to CB1 receptor on certain presynaptic terminals |
| Nitric oxide and ATP may sometimes function as what? | a neurotransmitter |
| What are AMPA and NMDA? | receptors that are excitatory glutamte-gated channels |
| What are the characteristics of an AMPA-gated channel? | it is permeable to Na and K (but not Ca) and it depolarizes the membrane by allowing Na to enter the cell |
| What are the characteristics of NMDA-gated channels? | they are permeable to Na, K and Ca and the inward current is voltage dependent |
| What three steps are involved in the transmission of G-protein coupled receptors? | binding of neurotransmitter to receptor protein, activation of G-protein and activation of effector system |
| What do kinases do? | they add a phosphate group via transfer from ATP |
| What do protein phosphatases do? | they remove a phosphate groups |
| What do G-protein systems provide? | A signal amplification |
| Divergence: | neurotransmitter activates more than one subtype of receptor to get more than one response |
| Convergence: | several different transmitters activate their own receptor type to affect the same effector system |
| Plasma membrane transporters uses what kind of transport? | cotransport- Na and transmitter |
| Vesicular membrane transpoters use what kind of transport? | counterport - carry H out and transmitter in |
| What is released from presynaptic neuron in response to Ca and binds to purinergic receptors such as transmitter-gated cation channels and G-protein coupled receptors? | ATP acting as a neurotransmitter |
| What do endogenous cannabinoids do? | they act on presynaptic terminals (retrograde messenger) feedback system to regulate synaptic transmission (release stimulated by Ca) |
| What can G-proteins stimulate? | they can stimulate adenylyl cyclase to convert ATP to cAMP |
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