pt 2 Flashcards
What do nerve cells generate to encode, process, and transfer information?
Electrical signals
These signals are essential for neuronal communication.
How can electrical signals in nerve cells be measured?
As changes in membrane potential via microelectrodes connected to a voltmeter
This technique allows for the observation of neuronal activity.
What is the resting membrane potential (Vrest)?
The constant voltage across the membrane at rest, ranging from -40 to -90 mV
This reflects the electrical gradient established across the neuronal membrane.
What is the charge distribution of a neuron at rest?
Negative inside and positive outside
This polarization is crucial for the generation of action potentials.
What are the primary components responsible for ion movements across neuronal membranes?
Active transporters and ion channels
What causes the resting membrane potential?
Electrochemical gradients of ions and differences in ion permeability
What is the role of the Na+/K+ pump in resting membrane potential?
3 Na+ out and 2 K+ in per ATP
What contributes to the resting membrane potential apart from the Na+/K+ pump?
- K+ leak channels (higher K+ permeability)
- Repulsion of Cl- by negatively charged proteins within the cytoplasm
What is electrochemical equilibrium (Ex)?
Balance of chemical and electrical forces until dynamic equilibrium is reached (no net movement)
What does the Nernst Equation predict?
The electrochemical potential generated across the membrane at electrochemical equilibrium for a single permeant ion
What is the Goldman equation used for?
Calculating equilibrium potential for multiple permeant ions
What is a receptor potential?
A change in potential when sensory neurons are stimulated
What is a synaptic potential?
A change in potential when one neuron stimulates another across a synapse
What is an action potential?
A nerve impulse or spike that travels along an axon
What characterizes a passive response?
Subthreshold; graded based on stimulus intensity and distance from the stimulus
What is the nature of an active response?
All-or-none; amplitude does not change with distance, stimulus intensity encoded in frequency
What phases are present in all action potentials?
- Rising/overshoot phase (depolarization)
- Falling phase (repolarization)
- Undershoot phase (hyperpolarization)
How do action potentials differ among neurons?
In amplitude, duration, and/or speed
What is the resting membrane potential value?
-70 mV
What primarily determines the resting membrane potential?
[K+] gradient across the membrane
What happens to the resting membrane potential when external [K+] concentration increases?
Depolarizes the resting membrane potential
Why is the membrane more permeable to K+ at rest?
Due to leak K+ channels
What is the role of Na+ in generating action potentials?
Important for generation of action potentials; magnitude and rise speed depend on [Na+] gradient across the membrane
