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Assignment 2.2 Solution

The document describes the principle and process of remotely measuring action potentials in nerves and muscles. Electrodes placed on the skin detect the brief electrical signals generated when an action potential propagates along a nerve or muscle fiber. The signals are amplified and recorded, then analyzed to determine characteristics of the action potential like amplitude, duration, and propagation velocity. This information can be used to diagnose nerve and muscle disorders or study physiology.

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35 views2 pages

Assignment 2.2 Solution

The document describes the principle and process of remotely measuring action potentials in nerves and muscles. Electrodes placed on the skin detect the brief electrical signals generated when an action potential propagates along a nerve or muscle fiber. The signals are amplified and recorded, then analyzed to determine characteristics of the action potential like amplitude, duration, and propagation velocity. This information can be used to diagnose nerve and muscle disorders or study physiology.

Uploaded by

Han ho
Copyright
© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
Available Formats
Download as PDF, TXT or read online on Scribd
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Assignment 2.

2 Solution
1. (10’)

The principle behind remote measurement of propagating action potential along a nerve or muscle
fibre is based on the fact that when an action potential is generated in a nerve or muscle fibre, it
produces a brief but measurable electrical signal that can be detected on the skin surface. This
electrical signal is generated by the movement of ions across the cell membrane of the nerve or
muscle fibre, and it propagates along the length of the fibre.

The electrodes placed on the skin surface detect this electrical activity and convert it into a voltage
signal that can be amplified and recorded by an instrument. The recorded signal can then be
analysed to determine the characteristics of the action potential, such as its amplitude, duration, and
velocity of propagation.

Steps of measurement

(a) Electrodes are placed on the skin above the nerve or muscle being studied.

(b) A stimulus is applied to the nerve or muscle, which generates an action potential.

(c) The electrodes detect the electrical activity generated by the action potential.

(d) The electrical activity is amplified and recorded by an instrument, such as an oscilloscope or
electromyography (EMG) machine.

(e) The recorded electrical activity can be analysed to determine the characteristics of the action
potential, such as its amplitude, duration, and velocity of propagation.

(f) The results can be used to diagnose nerve or muscle disorders, monitor the progress of treatment,
or study the physiology of nerve and muscle function.

2. (20’)

(a) (5’)

The velocity of the traveling signal v=15m/s and rising time is Δt=0.5ms, then
b=15m/s*0.5ms=7.5mm, which represents the dipole distance between +q and –q.

(b) (15’)

Assuming b<<r, we can treat the model as a pair of dipole, and get the equation from class’s lecture
that:

Where we treat all constant parameters as C. In this case, r=10cm, ΔV=100mV, roughly we get

∆𝑉
Where 𝐶 ′ = 𝐶 𝑟2
Sketch is drawn below:

From the graph, we can see that the potential reaches zero value at θ=90°, and reaches the
maximum at 0° and 180°.

3. (20’)

I – II + III = 0 = I -1.0 + 0.5, from which I = 0.5

Therefore, the scalar magnitude on lead I is 0.5mV.

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