Neurons and Action Potentials quiz #2 Flashcards
Neurons and Action Potentials quiz #2
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What are synaptic vesicles?
Synaptic vesicles are membrane-bound sacs in the axon terminal that store neurotransmitters. What is the synaptic cleft?
The synaptic cleft is the small gap between the presynaptic and postsynaptic cells at a synapse. What are ionotropic receptors?
Ionotropic receptors are membrane receptors that act as ligand-gated ion channels, opening in response to neurotransmitter binding. What are metabotropic receptors?
Metabotropic receptors are membrane receptors that activate second messenger pathways, often through G-proteins, after neurotransmitter binding. What is an excitatory postsynaptic potential (EPSP)?
An EPSP is a depolarization of the postsynaptic membrane that increases the likelihood of an action potential. What is an inhibitory postsynaptic potential (IPSP)?
An IPSP is a hyperpolarization of the postsynaptic membrane that decreases the likelihood of an action potential. How do ionotropic receptors cause EPSPs or IPSPs?
If ionotropic receptors allow positive ions in, they cause EPSPs; if they allow negative ions in, they cause IPSPs. What is temporal summation?
Temporal summation is the addition of postsynaptic potentials that occur in quick succession at the same synapse. What is spatial summation?
Spatial summation is the addition of postsynaptic potentials from multiple synapses occurring simultaneously. Where are the sodium channels that trigger action potentials located?
The sodium channels that trigger action potentials are located at the axon hillock. How are neurotransmitters removed from the synapse?
Neurotransmitters are removed by reabsorption (often by glial cells) or by enzymatic degradation. What is acetylcholine and where is it used?
Acetylcholine is a neurotransmitter used in both the central and peripheral nervous systems, with various effects depending on the receptor. What effect does acetylcholine have at the neuromuscular junction?
At the neuromuscular junction, acetylcholine has an excitatory effect, causing muscle contraction. What effect does acetylcholine have in heart muscle?
In heart muscle, acetylcholine has an inhibitory effect, slowing the heart rate. How is acetylcholine removed from the synapse?
Acetylcholine is degraded by the enzyme acetylcholinesterase. What are the major amino acid neurotransmitters?
The major amino acid neurotransmitters are glutamate, glycine, and GABA. What is the main excitatory neurotransmitter in the central nervous system?
Glutamate is the main excitatory neurotransmitter in the central nervous system. What is the main inhibitory neurotransmitter in the central nervous system?
GABA is the main inhibitory neurotransmitter in the central nervous system. How do drugs like Xanax and ethanol affect GABA receptors?
Ethanol stimulates GABA receptors, while Xanax keeps the GABA-A receptor channel open longer, both enhancing inhibitory effects. What are monoamine neurotransmitters?
Monoamines are neurotransmitters derived from aromatic amino acids, including serotonin, dopamine, and norepinephrine. What is the role of serotonin in the nervous system?
Serotonin is involved in the enteric nervous system and in regulating mood and feelings of happiness in the central nervous system. What is the role of dopamine in the brain?
Dopamine is involved in reward pathways and is associated with addiction. What is the role of norepinephrine in the nervous system?
Norepinephrine acts as a neurotransmitter in the sympathetic nervous system and also functions as a hormone. What are neuropeptides and give an example?
Neuropeptides are peptide neurotransmitters; an example is endorphins, which suppress pain and induce euphoria. What are endorphins and their function?
Endorphins are endogenous opioids that suppress pain signals and induce a sense of euphoria. What is nitric oxide's role as a neurotransmitter?
Nitric oxide is a gaseous neurotransmitter that diffuses widely and is not restricted to pre- to postsynaptic transmission. What are neurotoxins?
Neurotoxins are poisons that damage nerve tissue, often by interfering with ion channels or neurotransmitter receptors. What is tetrodotoxin and how does it affect neurons?
Tetrodotoxin is a neurotoxin that blocks voltage-gated sodium channels, preventing action potentials and potentially causing death. What is the function of glial cells in neurotransmitter removal?
Glial cells often reabsorb neurotransmitters from the synapse, helping terminate the signal. What is the axon hillock and its significance?
The axon hillock is the region where the axon joins the cell body and is the site where action potentials are initiated. How do EPSPs and IPSPs influence action potential generation?
EPSPs depolarize the membrane and increase the chance of an action potential, while IPSPs hyperpolarize and decrease the chance. What is the role of calcium ions in neurotransmitter release?
Calcium ions enter the axon terminal through voltage-gated channels and trigger synaptic vesicles to release neurotransmitters. What is the difference between presynaptic and postsynaptic cells?
The presynaptic cell sends the signal (releases neurotransmitter), while the postsynaptic cell receives the signal. What is the function of the sodium-potassium pump in maintaining resting potential?
The sodium-potassium pump maintains resting potential by pumping sodium out and potassium into the cell, creating ion gradients. How do neurotransmitters exert different effects in different tissues?
The effect of a neurotransmitter depends on the type of receptor it binds to in the target tissue. What is the function of the myelin sheath in action potential propagation?
The myelin sheath insulates the axon, allowing action potentials to travel faster by jumping between nodes of Ranvier. What is the significance of the refractory period in action potential propagation?
The refractory period prevents the action potential from traveling backward and ensures one-way propagation. What is the main difference between chemical and electrical synapses?
Chemical synapses use neurotransmitters to transmit signals, while electrical synapses transmit signals directly through gap junctions. How does the frequency of action potentials encode information?
The frequency of action potentials encodes the intensity of a stimulus; higher frequency means stronger signal. What is the role of ligand-gated ion channels in synaptic transmission?
Ligand-gated ion channels open in response to neurotransmitter binding, allowing ions to flow and change the postsynaptic membrane potential.
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