Exam 1 Flashcards
What is a sodium voltage-gated ion channel made of?
six transmembrane (TM) regions that are repeated four times within a single SCN gene and 4 TM domains
What are the properties of chloride gated channels?
2 subunits that form a dimer, where each subunit has a pore
What is the effect of TTX blocking sodium channels?
Stops depolarization which stops APs and can no longer transmit signals
What is the effect of scorpion a/b toxins?
Sustained depolarization increasing excitability leading to muscle spasms
What are symporters?
Moves 2 different molecules in the SAME direction (ex. reabsorption in digestive tract)
What are antiporters?
Moves 2 different molecules in DIFFERENT directions (ex. sodium potassium pump)
What is an absolute refractory period?
The inactivation of the sodium channels prevents them from re-opening until Vm is back at resting
Why is there an absolute refractory period?
Prevents overexcitation and temporally separates successive action potentials
How does AP conduction work?
Initiation zone spikes which depolarizes PM and repeats down the axon until it reaches the terminal
What is shunting inhibition?
neural inhibition characterized by a chloride flows through activated GABAA receptors into neurons causing hyperpolarization
How does shunting inhibition occur?
Inhibitory transmitters open chloride channels until the membrane potential (Vm) is close to the chloride equilibrium potential
What affects conduction velocity?
axon diameter and leakiness of axon PM
What is saltatory conduction?
When the AP jumps from node of ranvier to the next
What is a tripartite synapse?
A pre-synaptic terminal and post-synaptic membrane encased by an astrocyte
Where are amino acids and amines synthesized?
axon terminals
What is an mEPP?
a type of postsynaptic response that occurs when a single quantum of neurotransmitter is spontaneously released from a presynaptic neuron
What is synapsin?
binds vesicles in the reserve pool
What is synaptobrevin (vSNARE)?
protein found on the membranes of synaptic vesicles that interacts with tSNARE
What is synataxin and SNAP-25 (tSNARE)?
These proteins are found on the presynaptic membrane in neurons stabilizing SNARE complex
What is a SNARE protein?
Together with v-SNAREs like synaptobrevin, syntaxin and SNAP-25 form the SNARE complex to allow for vesicle exocytosis
What is CaMKII?
Phosphorylates synapsin to release vesicles in reserve pool allowing them to move to PM for release
What are NSF/SNAPs?
Proteins that work together to disassemble SNARE complexes after membrane fusion
What is Synaptotagmin?
calcium-regulated fusion of synaptic vesicles with the presynaptic membrane and regulation of neurotransmitter release
How does botulism affect neurotransmitter release?
By cleaving SNAP proteins, it prevents fusion of synaptic vesicles to the presynaptic membrane and cannot release neurotransmitter
