ELM 8 Transmission w/in neurons Flashcards
Why does current attenuate in dendrites?
Current attenuates in dendrites due to the leakiness of the cell membrane, analogous to a leaky hose where current leaks out through the membrane.
What are the two types of signals involved in neuronal transmission?
Neuronal transmission involves both electrical signals within neurons and chemical signals between neurons.
How does attenuation in dendrites compare to that in axons?
Attenuation in dendrites is not as significant as in axons because dendrites typically involve shorter distances and receive many inputs, generating a strong initial signal.
What is the length constant, and why is it important for efficient transmission?
The length constant is the distance over which the voltage drops to 37% of its original value. It is important for efficient transmission because it determines how far a signal can propagate without significant attenuation.
What factors affect the length constant in signal transmission?
The length constant depends on the leakiness (Rm) and conductivity (Ri) of the membrane, as well as the diameter of the conducting core. Increasing insulation (decreasing Rm) and improving conductivity (decreasing Ri) can enhance the length constant.
: How was attenuation addressed in the transatlantic telegraph cable system?
In the transatlantic telegraph cable system, efficient transmission was achieved by using cables with large length constants, achieved through better insulation to reduce leakiness and better conducting cores to improve conductivity.
What modern problem is affected by attenuation, and how is it addressed?
Attenuation affects broadband speed, causing it to drop off with distance from the exchange. Fiber optic cables show less attenuation compared to traditional cables, providing a solution to this modern problem.
What was a significant issue related to attenuation in the Victorian era?
Attenuation was a significant issue in the transatlantic telegraph cable system during the Victorian era, where copper conducting cores with rubber insulation were used, leading to significant signal loss over long distances.
Why don’t axons show attenuation like dendrites?
Axons have a higher density of sodium channels than dendrites, which allows for the generation of action potentials (APs) along the entire length of the axon without attenuation.
What is saltatory conduction?
Saltatory conduction is the rapid transmission of action potentials along myelinated axons, where the action potential “jumps” from one node of Ranvier to the next, resulting in faster conduction velocity.
How do we achieve fast transmission in axons?
: Fast transmission in axons depends on increasing the axon’s length constant, which can be achieved by increasing membrane resistance (Rm), increasing axon diameter, or decreasing internal resistance (Ri).
What strategy is used by primitive animals to increase conduction velocity in axons?
: Primitive animals, such as squids, increase axon diameter to achieve rapid conduction velocity, allowing for rapid escape responses.
What technique is used to measure and manipulate the voltage in axons during experiments?
The voltage clamp technique is used in experiments involving axons. It involves inserting electrodes to measure the voltage (V) and “inject” current, allowing the voltage to be clamped at a particular value while measuring the current needed to maintain that voltage.
What is myelination?
: Myelination is the process by which axons are insulated by myelin sheaths, which are produced by oligodendrocytes in the central nervous system and Schwann cells in the peripheral nervous system.
: How does myelination affect the transmission of action potentials?
Myelination decreases the leak of current and increases the speed of transmission of action potentials along axons. It achieves this by allowing for saltatory conduction, where action potentials “jump” from one node of Ranvier to the next, resulting in faster conduction velocity.
