43 Questions
What is the threshold for initiating neuronal action potentials?
-55 mV
When does the inactivation gate of Na+ voltage-gated channels (VGC) close?
After activation gate opens
What happens to potassium VGC when the cell repolarizes?
They close
During the absolute refractory period, what prevents another action potential?
Activation gate of Na+ VGC is closed
How is information coded in action potentials?
By frequency
What type of axons conduct action potentials faster?
Myelinated axons
Which type of fibers are myelinated and conduct impulses at 12-130 m/s?
A fibers
What type of conduction do myelinated axons use?
Saltatory conduction
What is the speed of impulse conduction in A fibers?
12-130 m/s
What gates do sodium voltage-gated channels (VGC) have?
Activation gate and inactivation gate
What type of period requires a larger stimulus to reach threshold?
Relative refractory period
What type of channels open when the cell depolarizes?
Sodium VGC
What predicts membrane potential when the membrane is permeable to multiple ions?
Goldman Field Equation
What is the resting membrane potential of a neuron?
-70 mV
What occurs when the axonal membrane becomes more positive and Na+ voltage-gated channels open?
Depolarization
What is involved in repolarization of the axonal membrane?
Rapid K+ exit
What is the approximate membrane potential during resting state?
-70 mV
What is the primary requirement for action potential generation?
Opening of Na+ voltage-gated channels
What are the two gates of the sodium voltage-gated channel?
Activation gate and inactivation gate
Where do action potentials occur in a neuron?
Axon hillock, axon, and synaptic terminals
What is the main factor determining ion movement across neuronal membranes?
Permeability of membranes to charged particles
What is the primary requirement for depolarization of the axonal membrane?
Opening of Na+ voltage-gated channels
What predicts the equilibrium potential for a specific ion across a membrane?
Nernst Equation
What population of channels is unique to the axon, axon hillock, and synaptic terminal for action potential production?
Voltage-gated sodium channels
What is the membrane potential typically close to at rest in neurons?
-75 mV
What is the Nernst potential for K+ given the intracellular and extracellular concentrations of K+ (120 mM and 4 mM, respectively)?
-94 mV
What does the Nernst potential describe?
The membrane voltage at which a particle moves into and out of the cell at the same rate
What does Ohm's law describe in the context of biology?
The relationship between current, voltage, and resistance in physiological compartments
What is the membrane potential at which the inward and outward movement of an ion through a channel is balanced and equal?
Nernst potential
What does the Nernst potential not include?
The flow of ions (current) or the resistance of the membrane to flow
What is the formula for Ohm's law in the context of biological membranes?
$I = V/R$
Which type of receptors are linked to G-protein signaling and have long-lasting effects, including protein synthesis and intracellular signals?
Metabotropic receptors
What are essential inhibitory neurotransmitters in the CNS, regulating membrane potential through ionotropic and metabotropic receptors?
GABA and glycine
Which neurotransmitter is the most common excitatory neurotransmitter in the CNS, with NMDA receptors being vital for learning and memory?
Glutamate
What are the distinct functions of norepinephrine and dopamine in the nervous system?
Norepinephrine is excitatory, dopamine is inhibitory
What do graded potentials influenced by neurotransmitter action summate to influence?
Axon hillock threshold
Where do action potentials mainly originate?
Cell bodies
What do graded potentials permit communication over?
Short distances
What are chemical synapses and graded potentials essential for?
Integrating inputs from multiple neurons
Where do graded potentials degrade over long distances?
Axon terminals
Which type of receptors are essential for regulating membrane potential through ionotropic and metabotropic actions?
G-protein coupled receptors
What are the roles of neurotransmitters and their receptors in the nervous system?
Controlling excitatory and inhibitory behaviors
Which type of receptors have long-lasting effects, including protein synthesis and intracellular signals?
Metabotropic receptors
Study Notes
Neurotransmitter Receptors and Graded Potentials Overview
- Metabotropic receptors are linked to G-protein signaling and have long-lasting effects, including protein synthesis and intracellular signals.
- Neurotransmitters and their receptors play crucial roles in excitatory and inhibitory behaviors in the nervous system.
- Acetylcholine acts on both excitatory and inhibitory muscarinic receptors, influencing cognitive function and autonomic nervous system activity.
- GABA and glycine are essential inhibitory neurotransmitters in the CNS, regulating membrane potential through ionotropic and metabotropic receptors.
- Glutamate is the most common excitatory neurotransmitter in the CNS, with NMDA receptors being vital for learning and memory.
- Norepinephrine and dopamine have distinct excitatory and inhibitory functions in the nervous system.
- Neurotransmitter binding to ionotropic receptors results in dendrite depolarization or hyperpolarization, affecting membrane potential.
- Graded potentials, influenced by neurotransmitter action, can be excitatory (EPSP) or inhibitory (IPSP) and can summate to influence membrane potential.
- Graded potentials are essential for integrating inputs from multiple neurons and determining whether the axon hillock reaches the threshold for an action potential.
- Chemical synapses and graded potentials add complexity to neuronal communication, allowing for varied and nuanced signaling.
- Action potentials mainly originate in dendrites and cell bodies, while graded potentials arise at trigger zones and propagate along the axon.
- Graded potentials permit communication over short distances and degrade over long distances, while action potentials propagate over longer distances.
Test your knowledge of neurotransmitter receptors and graded potentials with this comprehensive overview. Explore the roles of key neurotransmitters, such as acetylcholine, GABA, glutamate, norepinephrine, and dopamine, and their influence on excitatory and inhibitory behaviors in the nervous system. Gain insights into the mechanisms of metabotropic and ionotropic receptors, as well as the impact of graded potentials on membrane potential and neuronal communication.
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