Week 2 - Communication Within The Neuron Flashcards
What is the resting membrane potential?
The difference in electrical charge across the cell membrane, typically around -70 mV.
What forces contribute to the resting membrane potential?
- Diffusion
- Electrostatic pressure
- Transporter activity
What is the role of the transporter in maintaining resting membrane potential?
Moves sodium cations out of the cell, using energy to maintain the potential.
What is the charge distribution inside and outside the cell at resting potential?
Outside is positive (+ve); inside is negative (-ve).
What is the importance of the action potential in neurons?
It reflects the fundamental concept of electrical excitability and triggers signal transmission.
True or False: The cell membrane is completely impermeable to ions.
False
Fill in the blank: The resting membrane potential is maintained at approximately _______.
-70 mV
What is the primary reason diffusion of chemicals is insufficient for signaling in neurons?
It would be too slow.
What happens to sodium cations at rest in a neuron?
They tend to move into the cell but are pushed back out by the transporter.
What type of charge do cations carry?
Positive charge (+ve)
What type of charge do anions carry?
Negative charge (-ve)
How does electrostatic pressure affect ion movement?
Ions with the same charge repel each other, while ions with different charges attract each other.
Which ion is more permeable across the cell membrane, sodium or potassium?
Potassium
What does the term ‘electrical excitability’ refer to?
The ability of neurons to generate action potentials.
What percentage of the brain’s energy is used to maintain the resting potential?
A substantial proportion.
What is the overall nature of communication within a neuron?
Electrical signaling
What is the resting membrane potential?
The electrical charge across the neuronal membrane when the neuron is not active
It is essential for the initiation of action potentials.
What triggers an action potential?
A change in the resting membrane potential that reaches the threshold of excitation
This involves the opening of voltage-gated sodium channels.
What is the threshold of excitation?
The critical level to which the membrane potential must be depolarized to initiate an action potential, typically around -55 mV
List the phases of an action potential.
- Resting state
- Depolarization
- Repolarization
- Hyperpolarization
- Return to resting state
How do signals transmit from one neuron to another?
Through the release of neurotransmitters across a synapse
This involves the presynaptic neuron releasing neurotransmitters that bind to receptors on the postsynaptic neuron.
What is the difference between an action potential and a post-synaptic potential?
An action potential is a large, all-or-nothing signal, while post-synaptic potentials are small changes in membrane potential that can be excitatory or inhibitory
Fill in the blank: The action potential follows the _______ law, meaning it either occurs or does not occur.
[all-or-none]
What is the role of the myelin sheath in neuronal communication?
It insulates the axon, allowing action potentials to jump between nodes, increasing speed and efficiency
This process is known as saltatory conduction.
What happens during the depolarization phase of an action potential?
Sodium channels open, allowing Na+ ions to flood into the neuron, making the membrane potential less negative
What occurs during the repolarization phase of an action potential?
Potassium channels open, allowing K+ ions to exit the neuron, restoring the negative charge inside
Sodium channels close at this stage.
What is hyperpolarization?
A phase where the membrane potential becomes more negative than the resting potential
This occurs after repolarization due to the continued exit of K+ ions.
What are excitatory post-synaptic potentials (EPSPs)?
Small depolarizations that make the postsynaptic neuron more likely to fire an action potential
They result from the opening of cation channels.
What are inhibitory post-synaptic potentials (IPSPs)?
Small hyperpolarizations that make the postsynaptic neuron less likely to fire an action potential
They result from the opening of anion channels.
True or False: Action potentials can vary in size and shape.
False
Action potentials are always the same size and shape.
What is the significance of neurotransmitter receptors in the postsynaptic neuron?
They bind released neurotransmitters, leading to changes in conductance and the generation of post-synaptic potentials
What is the function of the presynaptic neuron?
To bring information to the synapse and release neurotransmitters into the synaptic cleft
What is the synaptic cleft?
The physical gap between the presynaptic and postsynaptic neurons, approximately 20 nm wide
