Chapter 13 - Synapses Flashcards
A specialized site of contact of one neuron with another neuron (or effector) is known as a
A. neuron.
B. receptor–neurotransmitter complex.
C. membrane.
D. synapse.
D. synapse.
Which of the following transmits information the fastest?
A. Ionotropic EPSP
B. Metabotropic IPSP
C. Electrical synapse
D. Fast EPSP
C. Electrical synapse
In an electrical synapse, the main structure responsible for transmission of an impulse from one cell to the next is ___________.
the gap junction
Ultimately, it is the _______ that determines whether the postsynaptic membrane produces an inhibitory postsynaptic potential (IPSP) or an excitatory postsynaptic potential (EPSP).
A. frequency of action potentials
B. movement of ions
C. neurotransmitter
D. receptor’s affinity for the neurotransmitter
B. movement of ions
Two sets of axons carry stimuli near the axonal hillock. One set produces an IPSP and the other set produces an EPSP. If both sets produce action potentials at the same time, what is the likely effect at the axonal hillock?
A. There will be a hyperpolarization.
B. There will be a depolarization.
C. An action potential will be produced.
D. The potentials created will cancel each other out.
D. The potentials created will cancel each other out.
The _______ is the flow of ions through all the channels that open in response to release of a neurotransmitter.
A. postsynaptic potential
B. synaptic current
C. action potential
D. voltage
B. synaptic current
Once acetylcholine is released into the synapse it
A. is actively pumped back into the presynaptic neuron.
B. crosses the postsynaptic membrane and then is broken down inside that cell.
C. is inactivated by calcium.
D. is broken down by acetylcholinesterase.
D. is broken down by acetylcholinesterase.
Which neurotransmitter elicits responses of both ionotropic and metabotropic receptors?
A. Acetylcholine
B. Dopamine
C. Glutamate
D. Both acetylcholine and glutamate
D. Both acetylcholine and glutamate
What are the steps in an action potential?
- Resting Membrane Potential
The membrane is most permeable to K+ at rest, there are leakage channels present and always open. - Rising Phase
The voltage-gated Na+ channels open, and high permeability to Na+ ions dominates, driving the membrane potential to E(Na). - Falling Phase
The Na+ channels inactivated shortly after they open, the voltage-gated K+ channels open, driving the Vm to E(K). - Recovery
The K+ channels remain open for a short time after the action potential, Na+ channels recover from their inactivation and open when depolarization occurs.
TRUE or FALSE? Synaptic transmission can be fast and inhibitory and exciatory.
TRUE
What are the two kinds of synapses?
- Electrical
Low resistance pathways that allow currents to flow DIRECTLY between neurons, changing the membrane potential. - Chemical
Currents escape between neurons and do not enter postsynaptic cell, a neurotransmitter carries signal across the synaptic cleft.
What is the difference between Iontropic receptor and Metabotropic receptor?
Iontropic: Fast excitation, inhibitory. Directly alters the permeability to ions
Metabotropic: Slow excitation, inhibitory. Triggers signaling cascade to secondary messengers.
What are advantages to chemical synapses?
- Amplify current flow
- Either be excitatory or inhibitory
- One-way, presynaptic neuron excites or inhibits the postsynaptic cell
- More modifiable, plasticity is important for development in the nervous system.
Differences between action potential and synaptic potential.
Action potential
- all or nothing
- same amplitude and duration as it travels through the axon
- travels long distances
Synaptic potential
- considerably smaller
- hyperpolarize with IPSP or depolarize with EPSP
- travels short distances
How do you measure quanta release?
Quanta
-neurotransmitters are released in multimolecular vesicles, about 5000 in each quantum
Measure through vesicle exocytosis.
