| Question |
Answer |
| What are the three layers of the heart? |
|
Endocardium (innermost layer), Myocardium (middle, muscular layer), and the Epicardium (outermost layer)
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| Which part of the pericardium is in direct contact with the epicardium, the visceral layer or the parietal layer? |
|
Visceral layer
|
| Which part of the pericardium is in direct contact with the mediastinum, the visceral layer or the parietal layer? |
|
The parietal layer
|
| What is the normal amount of fluid in between the visceral and parietal layers of the pericardium? |
|
10-30 ml
|
| Which ventricular wall is the thickest, the right or the left? |
|
The left ventricular wall is 2-3 times thicker than the right.
|
| The thickness of the ______ ventricle is necessary to generate the force needed to pump the body's blood into systemic circulation. |
|
Left
|
| The _____ atrium of the heart receives blood from the inferior and superior venae cavae and the coronary sinus. |
|
Right atrium
|
| Describe the flow of blood through the right side of the heart, starting from the right atrium: |
|
Blood enters the right atrium. As the atrium pressure increases the tricuspid valves open allowing blood to flow into the right ventricle. When the heart contracts, the pulmonic valves open and blood flows from the right ventricle into the pulmonary circulation via the pulmonary artery.
|
| Describe the flow of blood from the left side of the heart, starting with the left atrium: |
|
Pulmonary veins bring blood from the lungs and fills the left atrium. As the pressure builds, the mitral valve opens allowing blood to enter the ventricle. When the heart contracts, the aortic valve opens and blood is pushed out to the aorta
|
| At what point is blood flow due to high pressure? |
|
When it enters the aorta and flows into systemic circulation
|
|
|
| What are the thin, fibrous tissues called that attach the mitral and tricuspid valves to the papillary muscles of the ventricles? |
|
The chordae tendineae (heart strings)
|
| Which of the heart's valves are called the semilunar valves? |
|
The Pulmonic and Aortic
|
| When does the heart receive most of its blood, during systole or diastole? |
|
During diastole, when the heart is relaxed
|
| What arteries supply blood to the left atrium, left ventricle, intraventricular septum and part of the right ventricle? |
|
The left coronary artery (which arises from the aorta) and its two main branches: the left anterior descending artery and the left circumflex artery.
|
| Which artery(ies) supplies blood to the right atrium, right ventricle, and a portion of the posterior wall of the left ventricle? |
|
The right coronary artery (arising from the aorta)
|
| In 90% of the population, the ______ artery supplies blood to the Bundle of His and the atrioventricular node (AV node). |
|
Right coronary artery (arising from the aorta)
|
| Why does obstruction of the right coronary artery often lead to serious defects in the coronary conduction system? |
|
It supplies blood to the bundle of His and the AV nodes (both part of the conduction system)
|
| The electrical impulse conducted through the heart is called the... |
|
Action Potential
|
| The electrical impulse of the heart is initiated in the ______, also called the pacemaker of the heart. |
|
SA Node
|
| Describe the general pathway of the electrical current in the heart, starting with the SA Node... |
|
SA Node-beginning
Travels through the atria to the AV node
Bundle of His
Left and Right Bundle Branches (splits along the septum into each of the ventricles)
Purkinje Fibers (along the ventricle walls)
Ventricles contract
|
| What event signifies the beginning of the cardiac conduction cycle? |
|
The SA node depolarizing
|
| What event signifies the end of the cardiac conduction cycle? |
|
The contraction of the ventricles causing blood ejection into the pulmonary and systemic circulations (repolarization)
|
| When is the cardiac muscle in the absolute refractory period (meaning it will not respond to any stimuli), during systole or diastole? |
|
Systole
|
| When is the cardiac muscle in the relative refractory period (meaning it is regaining excitability), during systole or diastole? |
|
Diastole
|
| The P wave on the electrocardiogram signifies what cardiac event? |
|
The firing of the SA node (atrial depolarization)
|
| QRS on the electrocardiogram signifies what cardiac event? |
|
The firing of the AV node (depolarization of the AV node, roughly represents depolarization of the ventricles)
|
| What does the T wave on an electrocardiogram represent? |
|
Repolarization of the ventricles
|
| What does the U wave on an electrocardiogram represent? |
|
Can represent polarization of the Purkinje fibers (if seen) or it can be indicative of hypokalemia
|
| What does the intervals between the P, QRS, T and U waves indicate? |
|
The amount of time it takes an action potential to travel from one place in the heart to another.
|
| ________ results in the ejection of blood from the ventricles. |
|
Systole
|
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