Transmission Within Neurons Flashcards

1
Q

What is the ability to relay signals within or between neurones called?

A

Transmission

Transmission involves electrical signals within neurones and chemical signals between neurones.

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2
Q

What type of current is recorded in dendrites?

A

Dendrites: current attenuated

Dendrites exhibit attenuation of current due to their structural properties.

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3
Q

What analogy is used to explain why dendritic current attenuates?

A

Leaky hose analogy

This analogy compares the current flow in dendrites to water leaking from a garden hose.

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4
Q

What does the length constant (λ) represent?

A

The distance over which the voltage drops to 37% of its original value

The length constant is a crucial concept in cable theory related to signal transmission.

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5
Q

How can a cable engineer improve transmission efficiency?

A

By increasing Rm, decreasing Ri, or increasing diameter

These adjustments enhance the signal transmission properties of the cables.

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6
Q

True or False: Attenuation is a significant problem for dendrites.

A

False

Dendrites do not face significant attenuation issues due to short distances and multiple inputs.

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7
Q

What enables axons to transmit signals without attenuation?

A

Higher density of sodium channels

Axons have significantly more sodium channels compared to dendrites, allowing for effective action potential propagation.

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8
Q

What is the role of myelination in neuronal transmission?

A

To decrease current leak and increase conduction velocity

Myelination acts like insulation, improving the efficiency of signal transmission in axons.

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9
Q

What is saltatory conduction?

A

A wave of action potentials interspersed by segments of rapid cable conduction

This process allows for faster signal transmission along myelinated axons.

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10
Q

Fill in the blank: Intervals of myelination are called _______.

A

Internodes

Internodes are segments of the axon that are covered by myelin sheath.

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11
Q

What are the two types of cells that form myelin sheaths?

A

Oligodendrocytes and Schwann cells

Oligodendrocytes myelinate axons in the central nervous system, while Schwann cells do so in the peripheral nervous system.

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12
Q

How does myelination affect the density of sodium channels in axons?

A

High density of Na+ channels at nodes of Ranvier

The nodes of Ranvier have a significantly higher concentration of sodium channels compared to the internodes.

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13
Q

What is the maximum speed of action potential conduction in myelinated axons?

A

Up to 150 m/s

Myelinated axons can conduct action potentials much faster than unmyelinated axons.

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