Neurophys 2- Action potentials and Synaptic transmission

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38 Questions

Which neurotransmitter binds to the ionotropic receptor resulting in ion channel opening for sodium and calcium?


Which neurotransmitter is most important for inhibitory functions in the spinal cord?


Which neurotransmitter is associated with excitatory functions in the autonomic nervous system?


Which neurotransmitter binds to the nicotinic receptor resulting in sodium channel opening?


Which neurotransmitter is the most common excitatory neurotransmitter of the CNS?


Which neurotransmitter is associated with the neuromuscular junction and widely expressed throughout the brain as an excitatory neurotransmitter?


What determines the membrane potential of a cell?

The relative permeability of the membrane to each ion and the concentration of the ion on either side of the membrane

Why is the membrane potential of a neuron close to, but not the same, as the equilibrium (Nernst) potential for K+?

The permeability of the membrane to each ion has to be taken into account, which affects the overall membrane potential

What can cause channels to open or close?

Voltage, stretch, intracellular and extracellular messengers

What is required for the production of an action potential?

Presence of sodium voltage-gated channels

Where do action potentials occur?

The axon, axon hillock, and the synaptic terminal

What is the threshold membrane potential for the opening of Na+ voltage-gated channels?

-55 mV

During the depolarization phase, what drives Na+ into the cell?

Negative electrical force inside membrane

What happens during the absolute refractory period of the neuronal action potential?

When the inactivation gate of Na+ VGC is closed

What determines the conduction velocity of action potentials along a fiber?

Size of the axon diameter

What type of channels are mainly involved in generating graded potentials?

Ligand-gated or mechanically gated ion channels

What is the main characteristic of the conduction of graded potentials?

Decremental; permit communication over short distances, degrade over long distances

What determines the size of graded potentials?

Strength of stimulus

What is the role of EPSPs and IPSPs in the integration of graded potentials at the axon hillock?

EPSPs depolarize, while IPSPs hyperpolarize the membrane potential, affecting the likelihood of an action potential

Where do action potentials mainly arise and propagate?

Arise at trigger zones and propagate along the axon

What is the main difference between the conduction of graded potentials and action potentials?

Graded potentials exhibit decremental conduction, while action potentials propagate and permit communication over longer distances

Which type of axons exhibit saltatory conduction?

Myelinated axons

What is the speed of impulse conduction for C fibers?

0.5-2 m/sec

What is the role of v-SNAREs and t-SNAREs in vesicle release?

The regulate release of neurotransmitter into the synapse

What mediates calcium entry for vesicle release in chemical synapses?

Voltage-gated calcium channels in the presynaptic terminal

Both graded potentials and action potentials can summate


Both graded potentials and action potentials have refractory periods


Graded potentials are longer in duration than Action potentials


If graded potentials add up in a staircase fashion over time, they are known to participate in....

Temporal summation

The whole point of the action potential is to open ____ voltage gated channels in the presynaptic terminal


Which of the following prevents pre-mature release of the pre-synaptic vesicle?


Syntaxin and SNAP-25 are examples of ______

Which of the following is a v-SNARE?


Synaptotagmin acts on which of the following proteins to release the vesicle?


Acetylcholinesterase is an enzyme that....

Degrades acetylcholine

Botox treats migranes, wrinkles and muscle spasticity by impairing......


Graded potentials, like action potentials, always depolarize a neuron first


Graded potentials arise in:

Dendrites and cell body

Study Notes

Neural Conduction and Chemical Synapse

  • In non-myelinated axons, continuous conduction occurs as action potentials are reproduced along the length of the axon.
  • Myelinated axons exhibit saltatory conduction, where the electrical field "jumps" from one node of Ranvier to the next, allowing for faster impulse transmission.
  • A fibers are the largest, myelinated fibers conducting impulses at 12-130 m/sec, while C fibers are the smallest, non-myelinated fibers conducting impulses at 0.5-2 m/sec.
  • Chemical synapses involve the release of neurotransmitters from the presynaptic neuron, which then bind to receptors on the postsynaptic cell membrane.
  • Neurotransmitter vesicles are synthesized, packaged, and transported down the axon via microtubules to the presynaptic terminal.
  • The basic steps of neurotransmitter release involve the arrival of an action potential, opening of voltage-gated calcium channels, calcium entry, and release of neurotransmitter into the synaptic cleft.
  • Calcium entry for vesicle release is mediated by the opening of voltage-gated calcium channels in the presynaptic terminal, not from intracellular store release.
  • Vesicle release is regulated by v-SNAREs and t-SNAREs, which "zipper" together and disengage upon calcium binding, leading to the release of neurotransmitter into the synapse.
  • The release of neurotransmitter from vesicles is quick, taking 1-5 msec post-action potential.
  • Synaptic transmission is essential for communication between neurons and involves the precise release and binding of neurotransmitters.
  • The speed of impulse conduction varies based on fiber size, myelination, and the type of impulse being conducted.
  • The myelin insulation in myelinated axons allows for faster impulse transmission due to the jumping of the electrical field, compared to non-myelinated axons.

Test your knowledge of neural conduction and chemical synapse with this quiz. Explore topics such as continuous and saltatory conduction, neurotransmitter release, synaptic transmission, and the factors influencing impulse conduction speed.

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