Lab 3 - Heart Physiology & Sheep Heart Dissection

What is 1 of the cardiac conduction system?

Sinoatrial (SA) node

What is 2 of the cardiac conduction system?

Internodal pathways

What is 3 of the cardiac conduction system?

Atrioventricular (AV) node

What is 4 of the cardiac conduction system?

Bundle of His

What is 5 of the cardiac conduction system?

Right and left bundle branches

What is 6 of the cardiac conduction system?

Purkinje fibers

electro =

electrical

cardio =

heart

gram =

drawing

What does an ECG measure?

All of the electrical activity generated by heart at a given time (sum of all action potentials)

Where is the P Wave and what happens during this?

Atrial depolarization

Where is the QRS complex and what happens during this?

Ventricular depolarization and atrial repolarization

Where is the T Wave and what happens during this?

Ventricular repolarization

Contraction follows _______.

Depolarization

Relaxation follows ________.

Repolarization

Where is the P-R Interval and what happens during this?

Time required for atrial depolarization and contraction

Where is the P-R Segment and what happens during this?

Atrial contraction

Where is the Q-T Interval and what happens during this?

The combined time required for ventricular depolarization and repolarization

Where is the S-T Segment and what happens during this?

Ventricular contraction

Where is the T-P Segment and what happens during this?

Marks the end of ventricular repolarization and beginning of next cardiac cycle

What is the effects of exercise via the T-P segment?

The segment is shorter so less time between cardiac cycles

What is the effects of exercise via the R-R Interval?

Less time between QRS complexes

systole =

contraction

diastole =

relaxation

What causes heart sounds?

Pressure changes resulting in valves opening and closing

What causes the S1 “lub” sound?

AV valves closing (tricuspid and bicuspid)

What causes the S2 “dub” sound?

Semilunar valves closing

What is S3?

Not a primary heart sound, can hear it in children

Where does the first heart sound occur?

After the QRS complex

Where does the second heart sound occur?

After the T wave

True or False: The SA Node is the natural pacemaker of the heart.

True

What does the AV node do?

Creates a short delay in conduction

What does the Bundle of His do?

Conducts action potentials through the interventricular septum

What does the Purkinje fibers do?

Conducts electrical signals directly to contractile myocytes in ventricle