Conduction System of the Heart and Electrocardiography Exercise 31
NAME ____________________________________ LAB TIME/DATE _______________________
R E V I E W
S H E E T
EXERCISE
31
→
Conduction System of the Heart and Electrocardiography
The Intrinsic Conduction System
1. List the elements of the intrinsic conduction system in order, starting from the SA node. SA node → ATRIOVENTRICULAR (AV) NODE → → ATRIOVENTRICULAR (AV) BUNDLE
BUNDLE BRANCHES
PURKINJE FIBERS ATRIOVENTRICULAR (AV) NODE
At what structure in the transmission sequence is the impulse temporarily delayed? Why?
THIS DELAY IS IMPORTANT BECAUSE IT ENSURES THAT THE ATRIA HAVE
EJECTED THEIR BLOOD INTO THE VENTRICLES FIRST BEFORE THE VENTRICLES CONTRACT. 2. Even though cardiac muscle has an inherent ability to beat, the nodal system plays a critical role in heart physiology. What is that role? GENERATE ACTION POTENTIALS AT A GREATER FREQUENCY THAN OTHER CARDIAC MUS
THEY ARE THE PACEMAKER OF THE HEARTTHEREFORE, IT SETS THE HEARTRATE UNDER NORMAL
Electrocardiography
3. Define ECG. THE GRAPHIC RECORDING OF THE ELECTRICAL CHANGES (DEPOLARIZATION FOLLOWED DURING THE CARDIAC CYCLE REPOLARIZATION) OCCURING DURING THE CARDIAC CYCLE. 4. Draw an ECG wave form representing one heartbeat. Label the P, QRS, and T waves; the P–R interval; the S–T segment, and the Q–T interval. R S T P T
Q PR INTERVAL S QT INTERVAL 5. Why does heart rate increase during running? IN GREATER DEMAND WHEN OUR BODY IS UNDER THAT KIND
OF STRAIN. THE HEART MUST BEAT FASTER AND HARDER IN ORDER TO DELIVER THE LARGER AMOUNT OF BLOOD TO MUSCLES BEING USED WHEN RUNNING
207
6. Describe what happens in the cardiac cycle in the following situations. 1. 2. 3. 4. 5. 6. immediately before the P wave: during the P wave: HEART IS IN DIASTOLE
DEPOLARIZATION OF ATRIA CONTRACTION OF ATRIA
immediately after the P wave (P–R segment): during the QRS wave:
DEPOLARIZATION OF VENTRICLES CONTRACTION OF VENTRICLES
immediately after the QRS wave (S–T interval): during
R E V I E W
S H E E T
EXERCISE
31
→
Conduction System of the Heart and Electrocardiography
The Intrinsic Conduction System
1. List the elements of the intrinsic conduction system in order, starting from the SA node. SA node → ATRIOVENTRICULAR (AV) NODE → → ATRIOVENTRICULAR (AV) BUNDLE
BUNDLE BRANCHES
PURKINJE FIBERS ATRIOVENTRICULAR (AV) NODE
At what structure in the transmission sequence is the impulse temporarily delayed? Why?
THIS DELAY IS IMPORTANT BECAUSE IT ENSURES THAT THE ATRIA HAVE
EJECTED THEIR BLOOD INTO THE VENTRICLES FIRST BEFORE THE VENTRICLES CONTRACT. 2. Even though cardiac muscle has an inherent ability to beat, the nodal system plays a critical role in heart physiology. What is that role? GENERATE ACTION POTENTIALS AT A GREATER FREQUENCY THAN OTHER CARDIAC MUS
THEY ARE THE PACEMAKER OF THE HEARTTHEREFORE, IT SETS THE HEARTRATE UNDER NORMAL
Electrocardiography
3. Define ECG. THE GRAPHIC RECORDING OF THE ELECTRICAL CHANGES (DEPOLARIZATION FOLLOWED DURING THE CARDIAC CYCLE REPOLARIZATION) OCCURING DURING THE CARDIAC CYCLE. 4. Draw an ECG wave form representing one heartbeat. Label the P, QRS, and T waves; the P–R interval; the S–T segment, and the Q–T interval. R S T P T
Q PR INTERVAL S QT INTERVAL 5. Why does heart rate increase during running? IN GREATER DEMAND WHEN OUR BODY IS UNDER THAT KIND
OF STRAIN. THE HEART MUST BEAT FASTER AND HARDER IN ORDER TO DELIVER THE LARGER AMOUNT OF BLOOD TO MUSCLES BEING USED WHEN RUNNING
207
6. Describe what happens in the cardiac cycle in the following situations. 1. 2. 3. 4. 5. 6. immediately before the P wave: during the P wave: HEART IS IN DIASTOLE
DEPOLARIZATION OF ATRIA CONTRACTION OF ATRIA
immediately after the P wave (P–R segment): during the QRS wave:
DEPOLARIZATION OF VENTRICLES CONTRACTION OF VENTRICLES
immediately after the QRS wave (S–T interval): during