Chapter 5 Pt.2 Flashcards
What is the first step to anterograde synaptic transmission
The neurotransmitters are synthesized (created) in the neuron
What are Transporters
protein molecules that move substances across cell membranes, and package some neurotransmitters into vesicles
What is the second step in anterograde synaptic transmission
The neurotransmitter is packaged and stored within vesicles at the axon terminal
What is step 3 for the Anterograde synaptic transmission
The neurotransmitter is transported to the presynaptic membrane and released into the synaptic cleft
How is the neurotransmitter released into the synaptic cleft? (step 3)
Through an action potential that opens the gate for calcium (Ca2+) to influx the axon terminal.
Because of the calcium influx, the presynaptic membrane empties their contents into the synaptic cleft (exocytosis)
What is step 4 of anterograde synaptic transmission
the neurotransmitter binds to and activates receptors on the postsynaptic membrane
What are Ionotropic receptors
a membrane protein that acts as a binding site for a neurotransmitter, and also regulates ion flow
What is a metabotropic receptor
A membrane protein that acts as a binding site for a neurotransmitter that can open ion channels
In addition to interacting with the postsynaptic membranes receptors, a neurotransmitter may interact with receptors on the ___________ membrane. By doing so, it may influence the _____ that just released it. Specifically, a neurotransmitter may activate presynaptic receptors called _____________.
Presynaptic, cell, auto receptors
What do Autoreceptors do
they provide information about whether adjustments to synaptic communication should be made
The smallest postsynaptic potential is produced by the release of the contents of just 1 synaptic vesicle. This number of neurotransmitter molecules is called a _________.
Quantum (pl.quanta)
Producing a postsynaptic potential large enough to initiate a postsynaptic action potential requires the simultaneous release of many quanta from the presynaptic cell
The number of quanta released from the presynaptic membrane in response to a single action potential depends on two factors, what are they?
1) the amount of Ca2+ that enters the axon terminal in response to the action potential
2) the number of vesicles ducked at the membrane, waiting to be released
What is the fifth step of anterograde synaptic transmission
The neurotransmitter is removed (or degraded) from the synaptic cleft so it won’t continue to interact with a receptor
What are the 4 ways inactivation of a neurotransmitter can happen?
Diffusion = the neurotransmitter simply
diffuses away
Degradation = enzymes break it down
Reuptake = membrane transporters specific to that transmitter bring it back to the presynaptic axon terminal to reuse it
Astrocyte uptake = some neurotransmitters are taken up by the neighbouring astrocytes
How do Axoextracellular synapses secrete transmitter chemicals
they secrete it into extracellular fluid
How do axosecretory synapses secrete its transmitter
it synapses with blood capillaries and secretes its transmitter directly into blood
Synapses are not limited to axon terminals, dendrites also may send messages to other dendrites through _________________ synapses
dendrodendritic synapses
Some neurons can influence each other electrically through an _________ _______ (gap junction), where intracellular fluids or cytoplasm can come into direct contact
electrical synapse
When is a “Gap Junction” formed
when connexin proteins in one cells membrane crease a hemichannel that connects to a hemichannel in another cells membrane, allowing ions to pass from one neuron to the other
What is the difference between Excitatory and Inhibitory synapses
Excitatory: increase the activity of a receiving neuron
Inhibitory: decrease the activity of a receiving neuron
When a synapse is sent between axon terminals and cell bodies, its called ______________.
Axo-somatic
When a synapse is sent between axon terminals and muscles, its called _____________.
Axo-muscular
When a synapse is sent between axon terminals and dendrites (not dendrites to dendrites) its called _____________.
Axo-dentritic
When a synapse tis sent between axon terminals and other axons, its called __________.
axo-axonic
When a synapse is sent between axon terminals and other “synapses”, its called
Axo-synaptic
A _____________ synapse releases chemical transmitters into extracellular fluid
Axo-extracellular
A ____________ synapse releases transmitters into the bloodstream as hormones
axo-secretory
Excitatory synapses are usually located on a(n) ___________, whereas inhibitory synapses are usually found on a(n) ___________.
Dendrite; cell body/soma
