Chapter 5: Communication Between Neurons
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53 terms
Terms | Definitions |
|---|---|
 acetylcholine | chemical that sends message to slow down heart rate |
| epinephrine | aka adrenaline, chemical that carries excitatory message to speed up heart rate |
| cholinergic neurons | names for neurons that release acetylcholine |
| norepinephrine | neurotransmitter that acts like epinephrine in animals |
| nonadrengic neurons | neuron that releases norepinephrine |
| structure of synapse | 1. axon terminal 2. membrane encasing dendritic spine 3. small space in between |
| synapticcleft | tiny space in between presynaptic and postsynaptic membranes |
| postsynaptic membrane | membrane on the tip of the dendritic spine that has receptor molecules |
| presynaptic membrane | membrane of axon terminal, composed of mostly protein molecules and serve as channels, pumps and receptor sites |
| synaptic vesicles | round granules that contain chemical transmitters, gives terminal button shape |
| storage granule | holds several synaptic vesicles |
| microtuble | transports neurotransmitters to axon terminal |
| steps in neurotransmission | 1. synthesis 2. release 3. receptor action 4. inactivation |
| synthesis | first step in neurotransmission when transmitters are created by cell's DNA or from food and imported and stored in axon terminal |
| release | second step in neurotransmission where transmitters are transported to presynaptic membrane and released in response to action potentials |
| receptor action | third step in neurotransmission when transmitter traverses the synaptic cleft and interacts with the receptors of the target cell. normally, presynaptic membrane has a lot of calcium ions, and during action potential, voltage sensitive calcium channels open and flow into axon terminal |
| inactivation | fourth step of neurotransmission when transmitters taken back up into the axon or breaks down in synaptic cleft or just works indefinitely |
| classes of neurotransmitters | slower acting ones come from proteins from the cell's body, which are created by DNA faster acting ones come from food where transporter proteins absorb chemicals and mitochondria gives energy |
| calmodium | calcium binds to this that releases vesicles bound to presynaptic membrane or chemicals bound to filaments in axon terminal |
| receptor | site that occupies receiving membrane, type of neurotransmitter determines type of reaction |
| autoreceptors | receptors on own presynaptic membrane that serve as feedback loop in signal transduction, sensitive only to neurotransmitters released by own neuron that it's sitting on |
| factors in receptor activation | amount of calcium ions and amount of receptors, change based on neuron's function |
| ways to deactivate | 1. diffuse away from synapse 2. enzymes degrade them in cleft 3. reuptake neurotransmitters back into axon terminal 4. neurotransmitters taken up by neighboring glial cells |
| axodendritic synapse | type of synapse where axon terminal meets dendrite/dendritic spine |
| axosomatic synapse | type of synapse where axon terminal ends on cell body |
| axosynaptic synapse | type of synapse where axon terminal ends at another terminal |
| axoextracellular synapse | type of synapse where axon terminal is without specific target and is transmitted into extracellular fluid |
| axosecretory synapse | type of synapse where axon terminal synapse connects directly with capillaries |
| dendrodendritic synapse | type of synapse where dendrites connected with other dendrites, don't need axon terminal |
| excitatory synapses | usually on dendritic spines, round vesicles, denser membrane, wider cleft, large active zone |
| inhibitory synapses | usually on cell body, less dense receptors, flattened vesicles |
| criteria for neurotransmitters | 1. chemicals must be synthesized in neuron or present already 2. when neuron active, chemical must be released and produce a response in target cell 3. receptor action must be obtained when chemical experimentally placed on target 4. mechanism must exist for deactivating or removing chemical |
| putative transmitter | chemical that's suspected of being a neurotransmitter but hasn't met all the criteria yet |
| glycine | inhibitory transmitter in Renshaw cell |
| types of neurotransmitters | 1. small molecule transmitters 2. neuropeptides 3. transmitter gases |
| small molecule transmitters | small organic molecules that are synthesized/packaged for use in axon terminals, act relatively quickly then replaced ex: amines, amino acids, acetylcholine |
| dopamine | amine that plays role in coordinating movement, attention and learning, small molecule transmitter |
| role limiting factor | when amount of enzyme 1 is limited so it affects rate at which later chemicals can be synthesized |
| serotonin | amine that regulates mood, aggression, pain, respiration. small molecule transmitter |
| glutamate | amino acid transmitter related to GABA, known as "workhorse of nervous system." small molecule transmitter |
| gamma-aminobutyric acid | formed by simple modification of glutamate, small molecule transmitter used a lot in nervous system |
| histamine | amino acid transmitter that constricts smooth muscles. present in allergies. small molecule transmitter |
| peptide transmitter | short chains of amino acids that are produced in axon terminals, but mostly created in ribosomes and transported through microtubules. transported slowly and not replaced quickly, but have huge range of functions in nervous system. can't be taken orally because degraded in digestion |
| transmitter gases | easily cross cell membrane when they become active, messenger for different parts of the body. activates metabolic processes and controls production of other neurotransmitters ex: nitric oxide, carbon monoxide |
| ionotropic receptors | movement of charged atoms across cell membrane when membrane charge fluctuates. has binding site AND pore brings about very rapid changes in membrane voltage because binding immediately changes channels |
| metabotropic receptor | one protein that spans cell membrane without own pore but does have transmitter binding receptor |
| G proteins | proteins that translate chemical message into biochemical activity. 3 subunits and alpha subunit detaches and binds to other proteins |
| second messenger | the chemical that the alpha subunit activates and carries message to other structures |
| activating system | coordinates wide areas of brain to act together, each system has different behaviors but they overlap |
| cholinergic system | controls waking behavior, maintains neuron excitability, loss leads to Alzheimer's disease |
| dopaminergic system | 2 pathways: 1. nigrostriatial from substantia nigra, which takes part in coordinating movement and loss leads to parkinson's disease 2. mesolimbic from midbrain nuclei, causes dopamine release for feelings of reward and pleasure, excessive activity leads to schizophrenia |
| nonadrenergic system | system that stimulates neurons to change structure, organizes movements, decrease leads to major depression while increase leads to mania |
| serotonergic system | plays role in wakefulness, learning, decrease leads to depression while increase leads to OCD |
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