Topic 33

Question 1

Give four examples of body surface biopotentials

Answer 1

Electromyogram (Muscle Movement) (EMG)

Heart Operation (Electrocardiogram) (ECG)

Brain Operation (Electroencephalogram) (EEG)

Question 2

Describe the depolarisation in the heart

Answer 2

SA Node (Pacemaker) - Contracts both atria

To

AV Node - Contracts the ventricles

Repolarisation and repetition

Question 3

Describe the Eithoven Triangle

Answer 3

Positioning of electrodes:

Right Arm

Left Arm

Left Leg

Question 4

Describe a typical II Lead ECG Signal

Answer 4

1. 0.25 Seconds: Small increase, Atrial depolarisation (P)
2. 0.5 Seconds: High peak, Ventricals Depolarise (QRS)
3. Small increase, Ventricals Repolarise (T)
4. 1 Second: Cycle Repeats

Question 5

What is a wilson-type arrangement?

Answer 5

Where a unipolar lead is aded to the bipolar lead.

(Indifferent Electrode)

Question 6

Describe EEG

Answer 6

Electrodes placed on scalp (4-16)

Different waes are classified according to their frequencies

Question 7

Alpha waves

Answer 7

=20µV - Resting Phase (Sleeping)

Question 8

Beta Waves

Answer 8

<20 µV - Brain activity from counting or listening

Question 9

Delta Waves

Answer 9

50 - 100 µV - Rarely observed

Question 10

Theta Waves

Answer 10

Appears among ill conditions