Exam 1 pt 2 Flashcards
Which of the following evolutionary adaptations result in increasing the speed of
conduction of action potentials by decreasing the longitudinal resistance of the
axon?
Increasing the diameter of the axon
Which of the following events is associated with depolarization of a neuronal
membrane?
Flow of cations into the cell
During the depolarizing phase of the action potential, the voltage-gated Na+
channel is in which conformation?
Open/activated
Voltage-gated Na+ channels can be blocked by treating neurons with…
Tetrodotoxin (TTX)
During the absolute refractory period for a neuron, most voltage-gated Na+
channels are in which conformation?
Closed and not capable of opening
An action potential’s velocity depends upon…
Answers A and B are both correct (Membrane resistance, longitudinal resistance, magnitude of depolarization)
The axons with the fastest action potential velocities would have…
both A and B are correct (myelination and thick axon diameters)
If a membrane is at its Reversal Potential (Erev) then…
Its emf = 0
An inhibitory neurotransmitter may…
Answers A, B, and C are all correct (increase gk , allowing K+to leave cell, thereby hyperpolarizing it, . increase gCl , allowing Clto
enter cell, thereby hyperpolarizing it, inhibit Ca2+ channels, which are required for neurotransmitter release)
Which of the following proteins (or protein complexes) is required for the
FUSION (not docking) of synaptic vesicles with the plasma membrane?
Synaptotagmin
What is the primary neurotransmitter released by postganglionic cells of
vertebrate sympathetic neurons?
norepinephrine
Stimulus intensity, or strength, is encoded in…
frequency of action potentials with stronger stimuli eliciting higher
frequencies.
The purpose of acetylcholinesterase is to…
break down acetylcholine at synapses to limit its availability for
activating its receptor
When a single synaptic input fires repeatedly, generating a cumulative effect
on postsynaptic membrane potential, that phenomenon is known as…
temporal
Which of the following is (are) true regarding PEPTIDE neurotransmitters?
Both answers A and B are correct ( Many may act as neurotransmitters and as hormones, Some are released from multiple tissues, such as sensory neurons, autonomic neurons, CNS neurons, and intestinal endocrine cells)
What is the effect of heterosynaptic facilitation on SENSORY neurons?
action potential is prolonged
Voltage-gated K+ channels can be blocked by treating neurons with
TEA
Which part of a neuron has the highest density of voltage-gated Na+ channels?
the axon hillock
What experiments did Galvoni conduct?
He crushed muscle and saw that the nerve was stimulated when unlike metals completed the circuit to stimulate uncrushed muscle.
What does the intercellular electrode measure?
Action potential: if you inject neg current, it polarizes the cell. If you inject enough current you reach the threshold potential and cause a conformational change.
Capacitors store ___
charge
What effect does more leak channels have on resistance?
It lowers resistance (shortens response)
Nernst eq:
58*log([I]out/[I]in)
What does the patch clamp technique do?
Helps understand channel density, refractory periods and single channels
What effect to ion channels have on membrane capacitance?
They create resistance
What is Tau?
The time it takes to reach 63% of the amplitude
What is lambda?
The length to drop 63% of from the max. Show axial resistance
What is needed for action potential to occur?
Open the voltage gated Na+ channels, open the K+ channels –> Na+ channels inactivate and K+ channels go back to resting. Action potential moves down the axon doing this
What is the myelin sheath made of?
Glial cell membrane
What is the effect of the myelin sheath?
Insulates. “Seperates the plates” to lower the capacitance, which means it does not have the neutralize the Na+, and can quickly jump to the next node
Compounded action potential…
Distinct humps on a graph: groups alpha, beta and gamma add up. Some groups are fast (tall hump) while some are much slower (short hump)
How does the vessicle containing neurotransmitter enter the synapse?
Ca2+ pulls the vessicle (binds to proteins that are docking it to the membrane) through.
What vesicle proteins allow neurotransmitter to dock to the membrane?
Synapsin (re-docking), synaptotagnin (fusion)
Action potential humps represent ____ vesicular events…
Single
What is the difference between stimulated and spontaneous vessicular events?
Stimulated = taller and has threshold
Spontaneous=shorter
What is the quantal hypothesis?
Transmitters are released in packets (shown by studying spontaneous vesicular events using Ca blockers)
What are metabitrophic receptors?
Open/close the channel when the transmitter binds