Synapses Flashcards
A specialized gap between neurons
Synapse
Automatic muscular responses to stimuli
Reflexes
The circuit from sensory neuron to muscle response
Reflex arc
What does the synapse do to the transmission of reflex impulses?
Delays neuron communication
Phenomenon: repeated stimuli within a brief time have a cumulative effect
Temporal summation
The neuron that delivers transmissions
Presynaptic neuron
The neuron that receives transmissions
Postsynaptic neuron
Rapid succession of weak stimuli is enough to produce _________
An action potential
Unlike action potentials, which are always depolarizations, graded potentials ________
May either be depolarizations or hyperpolarizations
Depolarization that results from a flow of sodium ions into the postsynaptic neuron
Excitatory postsynaptic period (EPSP)
Phenomenon: Synaptic inputs from separate locations combine their effects on a neuron
Spatial summation
Temporal summation and spatial summation ordinarily occur _______
Together/at the same time
Temporary hyperpolarization that results from potassium ions leaving the membrane or for chloride ions to leave the cell
Inhibitory postsynaptic potential (IPSP)
What ion gates open during an EPSP?
Sodium gate
What ion gates open during an IPSP?
Potassium or chloride gates
Can an inhibitory message flow along an axon?
No. Only action potentials propagate along an axon. Inhibitory messages—IPSPs—decay over time and distance
The summation of graded potentials from stimuli at different times
Temporal summation
The summation of potentials from different locations
Spatial summation
The balance between __________ increases are decreases the neuron’s frequency of action potentials
EPSPs and IPSPs
Set of nerves that accelerates the heartbeat, relaxes the stomach muscles, dilates the pupils of the eyes, and regulates other organs
Sympathetic nervous system
First sequence of chemical events at the synapse
Synthesize neurotransmitters
Second sequence of chemical events at the synapse
Action potential causes calcium to enter, releasing neurotransmitters
Third sequence of chemical events at the synapse
Neurotransmitter binds to receptor
Fourth sequence of chemical events at the synapse
Separation of neurotransmitters from the receptor
Fifth sequence of chemical events at the synapse
Reuptake of neurotransmitter by transporter protein for recycling or diffusion
Sixth sequence of chemical events at the synapse
Postsynaptic cells send reverse messages to control further release of neurotransmitters
Chemicals that affect another neuron
Neurotransmitters
Neurotransmitter that dilates nearby blood vessels, increasing blood flow to certain brain areas but are also poisonous large qualities
Nitric oxide
Neurons synthesize nearly all neurotransmitters from _______
Amino acids
Amino acid synthesized from choline which is abundant in milk, egg, and peanuts
Acetylcholine
Amino acids that are the precursors of dopamine, norepinephrine, and epinephrine
Phenylalanine and tyrosine
Amino acid that is the precursor to serotonin and can cross the blood-brain barrier by a special transport system. Found in foods like soy.
Tryptophan
What are three catecholamine neurotransmitters?
Epinephrine, norepinephrine, and dopamine
Tiny, nearly spherical packets that store high concentrations of neurotransmitter molecules
Vesicles
Enzyme that breaks down serotonin, dopamine, or norepinephrine into inactive chemicals to prevent harmful levels of accumulation
Monoamine oxidase (MAO)
What happens by blocking MAO?
Increases serotonin, dopamine, and norepinephrine levels in the brain
