Bio 219: Lab 15 - Electrocardiogram (Ecg)

Front 1

Define ECG

Back 1

an external recording of the electrical activity of the heart

provides information on the speed of electrical conduction through the cardiac conduction system used to diagnose abnormalities and diseases of the heart, measures electrical activity of the heart

Front 2

Define electrode

Back 2

conductor through which electricity enters of leaves an oject, substance, or region

Front 3

Define automaticity

Back 3

development of an action potential in pacemaker cells of the heart

Front 4

Define gap junctions

Back 4

in cardiac muscle allow action potentials to spread between cardiac cells by permitting the passage of ions between cells, producing depolarization of the heart muscle

Front 5

Locate the SA node and state the function

Back 5

SA node generates impulse; atrial excitation begins

Front 6

Locate the AV node and state the function

Back 6

Impulse delayed at AV node

Front 7

Locate the AV bundle and state the function

Back 7

Impulse passes to heart apex; ventricular excitation begins

Front 8

Locate the R/L bundle branches and state the function

Back 8

impulse passes to heart apex, ventricular excitation begins

Front 9

Locate the Purkinje fibers and state the function

Back 9

ventricular excitation complete

Front 10

What is the P wave?

Back 10

corresponds to the depolarization of the atria

Front 11

What is the QRS complex?

Back 11

corresponds to the initial depolarization of the ventricles

Front 12

What is the T wave?

Back 12

corresponds to the repolarization of the ventricles

Front 13

The time between each ECG cycle (measured as the R-R interval) is used to calculate ______.

Back 13

heart rate

Front 14

The ECG trace gives information on the speed of electrical conduction through the cardiac conduction system and can be used to .....

Back 14

diagnose a variety of abnormalities and diseases of the heart.

Front 15

What is the P-Q interval?

Back 15

the time in seconds from the beginning of the P wave to the beginning of the Q portion (first downward deflection) of the QRS complex.
• The P-Q interval corresponds to the time of atrial depolarization plus the conduction delay at the AV node

Front 16

What is the QRS interval?

Back 16

the beginning of the Q wave (downward deflection) to the end of the S component of the QRS complex. This corresponds to the initial rapid depolarization of the ventricles.

Front 17

What is the Q-T interval?

Back 17

The beginning of the Q wave to the end of the T wave. This corresponds to the entire period of ventricular excitation, and is an estimate of the time the ventricle are contracting (systole)

Front 18

What is the S-T interval?

Back 18

the end of the S wave to the beginning of the T wave. This corresponds approximately to the plateau phase of the ventricular action potential

Front 19

What is the T-Q interval?

Back 19

the end of the T wave to the beginning of the Q wave. This corresponds to the time the ventricular cells are back at their resting potential and is an estimate of the time the ventricles are relaxed (diastole).

Front 20

During exercise cardiac output,

Back 20

increases to meet the increased blood flow requirements of exercising muscles.
• Controlled by SNS division
• ANS sympathetic neurons innervate the heart to release norepinephrine
• Norepinephrine and Epinephrine bind to beta adrenergic receptors on cardiac cells at the SA node, AV node, and ventricular myocardium

Front 21

Diving reflex

Back 21

when underwater our bodies need to conserve oxygen in the blood by decreasing heart rate which decreases the cardiac output, which reduces he work load and oxygen requirement of the heart so that you can survive longer underwater.

Front 22

total change

Back 22

(Diving HR - Resting HR)

Front 23

percent change

Back 23

100 x (diving HR - Resting HR)/Resting HR

Front 24

Suppose a patient displays an extended P-Q interval on their ECG. What electrical events occur during the P-Q interval, and what can you conclude specifically about the cardiac conduction system in a patient with a longer than normal P-Q interval?

Back 24

During the P-Q interval is the time of atrial depolarization and the conduction delay at the AV node. With this you can conclude that the cardiac conduction system in a patient with a longer than normal P-Q interval has an abnormally in the right atrium which causes the elongated delay.

Front 25

Explain the physiological basis for the observed differences in heart rate and other ECG intervals (such as the P-Q, Q-T, and T-Q intervals) between the resting and exercise ECG. Describe the specific physiological control mechanisms that effect these changes in heart rate and other ECG intervals.

Back 25

P-Q interval: time in seconds from the beginning of the P wave to the beginning of the Q portion. First downward deflection of the QRS complex corresponds to the time of atrial depolarization plus the conduction delay at the AV node.
QT interval: corresponds to the entire period of ventricular excitation and is an estimate of the time the ventricles are contracting (systole)
T-Q interval: time the ventricular cells are back at their resting potential and is an estimate of the time the ventricles are relaxed (diastole)

During exercise, cardiac output increases to meet the increased blood flow requirements of the exercising muscles. Sympathetic neurons innervate the heart and release epinephrine and norepinephrine which bind to beta adrenergic receptors on cardiac cells at the SA node, AV node and ventricular myocardium