Synaptic Transmission Flashcards
Is Synaptic Transmission Chemical or Electrical?
Chemical
Lowei’s Critical Experiment
Frog Hearts and Vagas Nerves in a Solution He discovered the first neurotransmitter and named it Vagustoffe (now known as acetylcholine.
What was the first neurotransmitter?
Acetylcholine
Who discovered the first neurotransmitter?
Loewi
Where are Neurotransmitters synthesized?
in the presynaptic neuron
Where are thee molecules of neurotransmitters stored?
Synaptic vesicles in the cytoplasm of the presynaptic terminal
What is the role of synaptic vesicles?
Store neurotransmitter molecules until they are ready to be released.
What causes neurotransmitters to be released into the synaptic cleft?
Action potential caused by the influx of calcium ions.
Describe exocytosis
Calcium ion channels open causing an influx in calcium. The membranes of the vesicle and the cell fuse together allowing the neurotransmitters to diffuse out on their own. This is done through passive diffusion.
What does the neurotransmitter do once it is in the synaptic cleft?
Binds to a chemically gated protein receptor on the postsynaptic membrane.
What’s the difference between ionotropic and metabotropic?
Ionotropic are fast acting, short lived.
Metabotropic are slow acting, lasts longer and are more durable and persistent.
What are metabotropic receptors?
bind to a protein but they do not open a channel. An enzyme is activated and makes substance A into Substance B. Eventually a substance will be madee and bind to protein and open ion channel. It is much slower because it has to go through a cascade of metabolic changes called the second messenger system.
Excitatory postsynaptic potential (EPSP)
Depolarization usually through an influx of sodium or calcium ions.
Which ions cause an Excitatory Postsynaptic Potential?
Sodium and Calcium
What Ion is necessary for exocytosis?
Calcium
What happens when depolarization occurs?
Excitatory Postsynaptic Potential occurs
Inhibitory Postsynaptic Potential (IPSP)
Hyperpolarization through thee influx of chloride or potassium
What ions cause Inhibitory Postsynaptic Potential to occur?
Chloride and Potassium
What happens when hyperpolarization occurs?
Inhibitory Postsynaptic Potential
During hyperpolarization _______ leaves the cell leaving the inside more negative.
Potassium
During hyperpolarization ______ enters the cell causing the inside to be more negative.
Chloride
What are the three fates of a neurotransmitter?
Degradation by catabolic enzymes in the synapse
Re-uptake and degradation in cytoplasm of presynaptic terminal
Re-uptake and redepositing back into a synaptic vesicle.
Which neurotransmitters fall subject to all three fates? And which fate is most common for these neurotransmitters?
Dopamine and Norepinephrine
Re-uptake and redeposit
