BPK 407 Final Exam correctly answered
already passed
Define the term "electrode" with respect to human physiological recordings. - correct answer
✔✔- An electrode is a type of transducer which changes ionic current into electric current
- They generate their own Direct Current (DC) voltage on which cardiac electrical signals are
superimposed and transmitted to the electrocardiogram (ECG)
- Must be able to adhere to and remain in contact on all types of skin under a variety of
conditions
- Contains a gel component which hydrates the skin which lowers electrode-skin impedence
- Different types: flat plate, suction cups, disposable floating. All used to create direct contact;
almost become part of the skin
What is the purpose of shaving hair, abrading, and applying ethanol at the skin where an
electrode is to be placed? - correct answer ✔✔The purpose of preparing the skin is to increase
electrical conductivity.
Rubbing the skin with liquid solvents such as ethanol or ether remove skin oil
Shaving hair exposes skin. Prevents skin hair from preventing direct contact between the
electrode and the skin surface
Explain the Difference between "wire" or "patient cable" and "lead" with respect to
electrocardiography. - correct answer ✔✔The electrodes which measure the electrical activity
are attached to a "patient cable" which are made up of a bundle of wires
These wires transmit the electric signal from the electrode to the electrocardiograph.
The patient cable is connected to the electrocardiograph, the machine used to detect, amplify,
and display electrical potentials from depolarization and repolarization in the heart which can
be detected at the surface of the skin
,A "lead" is a specific configuration, or combination, of electrodes. Leads can be placed at
various locations and measure the electrical signal being transmitted to the skin at that
particular location.
Each lead has a positive and negative pole attached to the surface of the skin, which can then be
used to measure the spread of electrical activity within the heart. Upward deflection on the
ECG- is produced when electrical impulses travel towards a positive electrode.
Difference between the three: wire is a component of the patient cable. The patient cable is
attached to electrodes on the skin measuring electrical signals. A lead is the configuration of
electrodes which can measure movement of current to determine electrical activity and
direction in the heart
How can one record a 12 lead ECG with only 10 electrodes? - correct answer ✔✔A lead is a view
of the electrical activity of the heart from a particular angle across the body. Think of a lead as a
picture of the heart and the 10 electrodes give you 12 pictures. In other words, a lead is a
picture that is captured by a group of electrodes
12-lead ECG, there are 10 electrodes providing 12 perspectives of the heart's activity using
different angles through two electrical planes — vertical and horizontal planes.
When the positive electrode and the negative electrode are at the same electrical potential (ex.
voltage), does the ECG stylus deflect up, down, or remain unchanged? Explain. - correct answer
✔✔When current flows towards the positive electrode, the needle on the ECG will deflect
upwards. When current flows away from the positive electrode, the needle deflects downwards.
If the positive and negative electrodes are at the same electrical potential, no current will be
created and therefore there will be no current movement relative to the positive electrode. The
ECG stylus will remain unchanged?
When current flows toward the positive electrode, does the EKG stylus deflect up, down, or
remain unchanged? - correct answer ✔✔When current flows towards the positive electrode,
the needle on the ECG will deflect upwards. When current flows away from the positive
electrode, the needle deflects downwards.
,On which of the following - Lead I, Lead II or Lead III - would you expect the QRS complex to
have the highest positive amplitude? Explain. - correct answer ✔✔The mean electrical axis of
the heart is generally on an angle from the right shoulder down towards the left hip?
Lead II had a negative electrode at the right wrist and a positive electrode on the left ankle,
creating a similar path as the mean electrical axis (which can also change)
As the wave of depolarization moves down the interventricular septum and spreads through the
myocardium on the ventricles during ventricular systole, the QRS complex of the ECG should be
largest for Lead II as it is more in line with the wave of depolarization
What is the purpose of the reference electrode in electrocardiography (and other electrical
recordings from the body)? - correct answer ✔✔A reference electrode improves the quality of
the tracing
Allows the ECG to identify and eliminate "noise" found over a large region of the body
Once the noise is eliminated, the small electrical potential between two sites can be detected
much more clearly
Also important for reducing electrical signals from the muscles
Often called the ground electrode
Helps prevent electrical shock to the subject or operator
Provides low resistance pathway to earth for current which might reach the outer case of the
ECG machine due to a fault
Procedures where nerves or muscles are electrically stimulated from the surface, the current
from the stimulus travels not only into the tissues but also across the skin (stimulus artifact)
Stimulus artifact can distort or obliterate the much smaller signal being recorded from the nerve
or muscle unless it is diverted into the lower-resistance pathway to earth
Give three reasons for exercise stress testing. - correct answer ✔✔1) to diagnose an abnormal
response to exercise denoting cardiovascular disease
2) to assess the physical tolerance of patients with known cardiovascular disease
3) to assess the physical fitness of individuals without known cardiovascular disease
, What is a PAR-Q, and what is it used for? - correct answer ✔✔Physical activity readiness
questionnaire
Minimal standard for entry into low to moderate intense exercise programs
Identifies the small number of adults for whom physical activity might be inappropriate or those
who should have medical advice concerning the most suitable type of activity
Seven multiple "yes/no" questions. Yes response indicates individual should consult physician
before engaging in vigorous physical activity
First level screening device to identify the percentage of those who should have some medical
evaluation or direction before starting an exercise program
In what units should P-R interval be reported? - correct answer ✔✔In electrocardiography, the
PR interval is the period, measured in milliseconds, that extends from the beginning of the P
wave (the onset of atrial depolarization) until the beginning of the QRScomplex (the onset of
ventricular depolarization); it is normally between 120 and 200ms in duration.
What would you do if you were trying to measure the P-R interval, and it was so small that it
was hard to measure accurately? - correct answer ✔✔Change the chart speed on the ECG from
25mm/s to 50mm/s to have recordings which are more spread out
Change the sensitivity/gain on the ECG to a larger amplitude to have larger wave recordings.
PR interval < 120 ms suggests pre-excitation syndromes (the presence of an accessory pathway
between the atria and ventricles) or AV nodal (junctional) rhythm.
In what units should P-wave amplitude be reported? - correct answer ✔✔The combined
depolarisation wave, the P wave, is less than 120 ms wide and less than 2.5 mm high.
Amplitude
< 2.5 mm in the limb leads,
< 1.5 mm in the precordial leads
already passed
Define the term "electrode" with respect to human physiological recordings. - correct answer
✔✔- An electrode is a type of transducer which changes ionic current into electric current
- They generate their own Direct Current (DC) voltage on which cardiac electrical signals are
superimposed and transmitted to the electrocardiogram (ECG)
- Must be able to adhere to and remain in contact on all types of skin under a variety of
conditions
- Contains a gel component which hydrates the skin which lowers electrode-skin impedence
- Different types: flat plate, suction cups, disposable floating. All used to create direct contact;
almost become part of the skin
What is the purpose of shaving hair, abrading, and applying ethanol at the skin where an
electrode is to be placed? - correct answer ✔✔The purpose of preparing the skin is to increase
electrical conductivity.
Rubbing the skin with liquid solvents such as ethanol or ether remove skin oil
Shaving hair exposes skin. Prevents skin hair from preventing direct contact between the
electrode and the skin surface
Explain the Difference between "wire" or "patient cable" and "lead" with respect to
electrocardiography. - correct answer ✔✔The electrodes which measure the electrical activity
are attached to a "patient cable" which are made up of a bundle of wires
These wires transmit the electric signal from the electrode to the electrocardiograph.
The patient cable is connected to the electrocardiograph, the machine used to detect, amplify,
and display electrical potentials from depolarization and repolarization in the heart which can
be detected at the surface of the skin
,A "lead" is a specific configuration, or combination, of electrodes. Leads can be placed at
various locations and measure the electrical signal being transmitted to the skin at that
particular location.
Each lead has a positive and negative pole attached to the surface of the skin, which can then be
used to measure the spread of electrical activity within the heart. Upward deflection on the
ECG- is produced when electrical impulses travel towards a positive electrode.
Difference between the three: wire is a component of the patient cable. The patient cable is
attached to electrodes on the skin measuring electrical signals. A lead is the configuration of
electrodes which can measure movement of current to determine electrical activity and
direction in the heart
How can one record a 12 lead ECG with only 10 electrodes? - correct answer ✔✔A lead is a view
of the electrical activity of the heart from a particular angle across the body. Think of a lead as a
picture of the heart and the 10 electrodes give you 12 pictures. In other words, a lead is a
picture that is captured by a group of electrodes
12-lead ECG, there are 10 electrodes providing 12 perspectives of the heart's activity using
different angles through two electrical planes — vertical and horizontal planes.
When the positive electrode and the negative electrode are at the same electrical potential (ex.
voltage), does the ECG stylus deflect up, down, or remain unchanged? Explain. - correct answer
✔✔When current flows towards the positive electrode, the needle on the ECG will deflect
upwards. When current flows away from the positive electrode, the needle deflects downwards.
If the positive and negative electrodes are at the same electrical potential, no current will be
created and therefore there will be no current movement relative to the positive electrode. The
ECG stylus will remain unchanged?
When current flows toward the positive electrode, does the EKG stylus deflect up, down, or
remain unchanged? - correct answer ✔✔When current flows towards the positive electrode,
the needle on the ECG will deflect upwards. When current flows away from the positive
electrode, the needle deflects downwards.
,On which of the following - Lead I, Lead II or Lead III - would you expect the QRS complex to
have the highest positive amplitude? Explain. - correct answer ✔✔The mean electrical axis of
the heart is generally on an angle from the right shoulder down towards the left hip?
Lead II had a negative electrode at the right wrist and a positive electrode on the left ankle,
creating a similar path as the mean electrical axis (which can also change)
As the wave of depolarization moves down the interventricular septum and spreads through the
myocardium on the ventricles during ventricular systole, the QRS complex of the ECG should be
largest for Lead II as it is more in line with the wave of depolarization
What is the purpose of the reference electrode in electrocardiography (and other electrical
recordings from the body)? - correct answer ✔✔A reference electrode improves the quality of
the tracing
Allows the ECG to identify and eliminate "noise" found over a large region of the body
Once the noise is eliminated, the small electrical potential between two sites can be detected
much more clearly
Also important for reducing electrical signals from the muscles
Often called the ground electrode
Helps prevent electrical shock to the subject or operator
Provides low resistance pathway to earth for current which might reach the outer case of the
ECG machine due to a fault
Procedures where nerves or muscles are electrically stimulated from the surface, the current
from the stimulus travels not only into the tissues but also across the skin (stimulus artifact)
Stimulus artifact can distort or obliterate the much smaller signal being recorded from the nerve
or muscle unless it is diverted into the lower-resistance pathway to earth
Give three reasons for exercise stress testing. - correct answer ✔✔1) to diagnose an abnormal
response to exercise denoting cardiovascular disease
2) to assess the physical tolerance of patients with known cardiovascular disease
3) to assess the physical fitness of individuals without known cardiovascular disease
, What is a PAR-Q, and what is it used for? - correct answer ✔✔Physical activity readiness
questionnaire
Minimal standard for entry into low to moderate intense exercise programs
Identifies the small number of adults for whom physical activity might be inappropriate or those
who should have medical advice concerning the most suitable type of activity
Seven multiple "yes/no" questions. Yes response indicates individual should consult physician
before engaging in vigorous physical activity
First level screening device to identify the percentage of those who should have some medical
evaluation or direction before starting an exercise program
In what units should P-R interval be reported? - correct answer ✔✔In electrocardiography, the
PR interval is the period, measured in milliseconds, that extends from the beginning of the P
wave (the onset of atrial depolarization) until the beginning of the QRScomplex (the onset of
ventricular depolarization); it is normally between 120 and 200ms in duration.
What would you do if you were trying to measure the P-R interval, and it was so small that it
was hard to measure accurately? - correct answer ✔✔Change the chart speed on the ECG from
25mm/s to 50mm/s to have recordings which are more spread out
Change the sensitivity/gain on the ECG to a larger amplitude to have larger wave recordings.
PR interval < 120 ms suggests pre-excitation syndromes (the presence of an accessory pathway
between the atria and ventricles) or AV nodal (junctional) rhythm.
In what units should P-wave amplitude be reported? - correct answer ✔✔The combined
depolarisation wave, the P wave, is less than 120 ms wide and less than 2.5 mm high.
Amplitude
< 2.5 mm in the limb leads,
< 1.5 mm in the precordial leads
