3.2 Chemical Events At The Synapse Flashcards
Sequence of chemical events. 2. action potentials travel down the axon. At the presynaptic terminal, an action potential enables calcium to enter the cell. Calcium releases neurotransmitters from the terminals and into the ____ ____, the space between the presynaptic and postsynaptic neurons.
synaptic cleft
Sequence of chemical events. 1. the neuron synthesises chemicals that serve as neurotransmitters. It synthesises the smaller ____ in the axon terminals and synthesises ____ in the cell body.
neurotransmitters : neuropeptides
Sequence of events. 3. The released ____ diffuse across the cleft, attach to receptors, and alter the activity of the postsynaptic neurons.
molecules
Sequence of events. 4. The neurotransmitter molecules ____ from their receptors.
separate
Sequence of events. 5. The neurotransmitter molecules may be taken back into the presynaptic neuron for ____ or they may ____ away.
recycling : diffuse
Sequence of events. 6. Some postsynaptic cells send ____ messages to control the further release of neurotransmitters by presynaptic cells.
reverse
At a synapse, a neuron releases chemicals that affect another neuron. Those chemicals are known as it ____.
neurotransmitters
One neurotransmitter are acids containing an amine group (NH2) called ____ ____.
Amino acids.
Another neurotransmitter are chemicals formed by a change in certain amino acids, these are called ____.
monoamines
Another neurotransmitter is a chemical similar to an amino acid called ____.
acetylcholine
Another neurotransmitter is chains of amino acids called ____.
neuropeptides
Another neurotransmitter is a category of chemicals including adenosine and several of its derivatives called ____.
purines
Another neurotransmitter are ____ including nitric oxide and possibly others.
gases
Neurons synthesise nearly all neurotransmitters from ____ ____, which the body obtains from proteins in the diet.
amino acids
____ is synthesised from choline, which is abundant milk, eggs, and peanuts.
Acetylcholine
The amino acids ____ and ____, present in proteins, are precursors of dopamine, norepinephrine, and epinephrine.
phenylalanine : tyrosine
The amino acid ____, the precursor to serotonin, crosses the blood-brain barrier by special transport system that it shares with other large amino acids. It is present in the foods such as soy and maize.
tryptophan
Most neurotransmitters are synthesised in the presynaptic terminal, near the point of release. The presynaptic terminal stores high concentrations of neurotransmitter molecules in ____, tiny near spherical packets.
vesicles
It is possible for a neuron to accumulate ____ levels of a neurotransmitter.
excess
Neurons that release serotonin, dopamine, or norepinephrine container an enzyme, MAO (____ ____), that breaks down these transmitters into inactive chemicals.
monoamine oxidase
At the end of the axon, the action potential itself does not release the neurotransmitter. Rather, the depolarisation opens at ____ ____ ____ in the presynaptic terminal.
voltage-dependent calcium gates
Within 1 or 2 milliseconds after calcium enters the presynaptic terminal, it causes ____ – release of neurotransmitter in bursts from the presynaptic neuron into the synaptic cleft that separates one neuron another.
exocytosis
After its release from the ____ cell, the neurotransmitter diffuses across the _____ cleft to the _____ membrane, where it attaches to a ____.
presynaptic : synaptic : postsynaptic : receptor
The neurotransmitter takes no more than ____ to diffuse across the cleft, which is only ____ wide.
0.01 ms : 20 to 30 nm
Although the brain as a whole uses many neurotransmitters, no ____ neuron releases them all.
single
Many, perhaps most, neurons release a combination of ___ or ____ transmitters.
two or more
