Action Potential and Synapse

Post-tetanic facilitation is thought to be the result of which of the following? A) Opening of voltage-gated sodium channels B) Opening of transmitter-gated potassium channels C) A buildup of calcium in the presynaptic terminal D) Electrotonic conduction

C

Prolonged changes in neuronal activity are usually achieved through the activation of which of the following? A) Voltage-gated chloride channels B) Transmitter-gated sodium channels C) G-protein-coupled channels D) Voltage-gated potassium channels

C

Which statement concerning synaptic transmission is correct? A) When a specific population of synaptic terminals is spread over the considerable surface of a neuron, their collective effects cannot spatially summate and lead to initiation of an action potential B) Even if the successive discharges of an excitatory synapse occur sufficiently close in time, they can- not temporally summate and initiate an action potential C) A neuron is "facilitated" when its membrane potential is moved in the less negative or depolarizing direction D) Even when rapidly stimulated by excitatory synaptic input for a prolonged period, neurons typically do not exhibit synaptic fatigue

C

What are two types of synaptic receptors (NT binds to one of the following):

1. Ligand gated ion channels 2. Metabotropic, second messenger (75% G reactive proteins)

In Metabotropic, after channel is opened what three things are activated

1. activates either adenyl cyclase or guanyl cyclase 2. enzymes 3. gene transcription

what are 4 characteristics of synapses

1. fatigue 2. post-tetanic facilitation (increase in Ca+ in presynaptic terminal) 3. Synaptic delay 4. Summate (increase freq. of firing; temporal & spatial summation)

An input neuron to a diverging circuit causes the membrane potential of a target neuron to change from −65 millivolts to −55 millivolts. Which of the following best describes this change in membrane potential (in millivolts)? A) Excitatory postsynaptic potential = +10 B) Excitatory postsynaptic potential = −10 C) Inhibitory postsynaptic potential = +10 D) Inhibitory postsynaptic potential = −10

A

The excitatory or inhibitory action of a neurotransmitter is determined by which of the following? A) The function of its postsynaptic receptor B) Its molecular composition C) The shape of the synaptic vesicle in which it is contained D) The distance between the pre- and postsynaptic membranes

A

Which electrical event is characteristic of inhibitory synaptic interactions? A) A neurotransmitter agent that selectively opens ligand-gated chloride channels is the basis for an inhibitory postsynaptic potential B) Because the Nernst potential for chloride is about −70 mV, chloride ions tend to move out of the cell along its electrochemical gradient C) A neurotransmitter that selectively opens potassium channels will allow potassium to move into the cell D) An increase in the extracellular sodium concentration usually leads directly to an inhibitory postsynaptic potential

A

A transmitter substance released from a presynaptic neuron activates a second messenger G-protein system in the postsynaptic neuron. Which one of the following postsynaptic responses to the transmitter substance is NOT a possible outcome? A) Activation of cyclic adenosine monophosphate (cAMP) B) Activation of cyclic guanosine monophosphate (cGMP) C) Activation of gene transcription D) Closing an ion channel E) Opening an ion channel

D

The release of neurotransmitter at a chemical synapse in the central nervous system is dependent upon which of the following? A) Synthesis of acetylcholinesterase B) Hyperpolarization of the synaptic terminal C) Opening of ligand-gated ion calcium channels D) Influx of calcium into the presynaptic terminal

D

The resting potential of a myelinated nerve fiber is primarily dependent on the concentration gradient of which of the following ions? A) Ca++ B) Cl− C) HCO3− D)K+ E) Na+

D

Which of the following is characteristic of the events occurring at an excitatory synapse? A) There is a massive efflux of calcium from the pre-synaptic terminal B) Synaptic vesicles bind to the postsynaptic membrane C) Voltage-gated potassium channels are closed D) Ligand-gated channels are opened to allow sodium entry into the postsynaptic neuron

D

How to calculate net driving force on ion

difference in millivolts between the membrane potential (Vm) and the equilibrium potential for that ion

In Ligand gated, what ions enter or leave in each scenario Excitatory = Inhibitory =

excite = either calcium or sodium ions enter inhibit = either potassium ions leave or chloride ions enter

Resting membrane potential is closest to the Nernst potential for ____ due to large number of those channels in the membrane

potassium

Nernst Equations: E K+ = E Na+ = E Cl- =

K = -61 log Ki/Ko Na = -61 log Ki/Ko Cl = +61 log Ki/Ko

A neurotransmitter activates its receptor on an ion channel of a neuron, which causes the water-filled channel to open. Once the channel is open, ions move through the channel down their respective electro- chemical gradients --> change in membrane potential Which of the following best describes the type of channel and mechanism of ion transport? Ligand gated vs. Voltage Gated Simple diffusion vs. facilitated diffusion vs. secondary active transport

Ligand gated Simple Diffusion

Resting membrane potential (resting state) is re-established and maintained by what

Na+/K+ ATPase Pump

What occurs in Pre-synaptic terminal: 1. AP stimulates what channels to open: 2. Influx of ____ causes:

Neurotransmitter is released 1. voltage activated calcium channels 2. Ca+ causes release of NT by regulated exocytosis

Falling phase (repolarization)

Potassium OUT

Rising Phase (depolarization)

Sodium IN