Lecture 5 - Jan 30 Flashcards
What does the right vagus nerve typically handle in the heart?
SA node
What does the left vagus nerve typically handle in the heart?
AV node
How does sympathetic innervation compare to vagus nerve innervation in the heart?
Sympathetic innervation is widespread and covers more ventricular muscle.
What happens to heart rate if vagus nerve input is removed?
Heart rate increases significantly.
What is the typical heart rate at rest when sympathetic activity is removed?
About 60 beats per minute.
What is the innermost layer surrounding the heart called?
Serous pericardium
What is the function of the visceral layer of the serous pericardium?
Covers the outside of the heart and reduces friction.
What is the fibrous pericardium?
A thicker, less compliant layer surrounding the heart.
What are the two layers of the serous pericardium?
- Visceral layer
- Parietal layer
How do electrical signals move through the heart muscle?
Via gap junctions and electrical current through ions.
Which ion is most important for conducting action potentials in the heart?
Sodium
What is the orientation of muscle fibers in the ventricles?
Two thick muscle layers oriented at perpendicular angles.
What are the parts of the heart valves called?
Cusps or leaflets
How are the cusps of the AV valves attached to the ventricles?
Via chordae tendinae.
What role do papillary muscles play in heart valve function?
They reinforce AV valves to prevent backflow during ejection.
What is a normal ejection fraction (EF) for the heart?
58%
What distinguishes the bicuspid valve from the tricuspid valve?
Bicuspid has two cusps; tricuspid has three cusps.
What causes aortic stenosis?
Gum up of the aortic valve leading to difficulty in coronary perfusion.
What are the three cusps of the aortic valve?
- Left cusp
- Right cusp
- Posterior cusp
What is the function of the cardiac cartilaginous rings?
They insulate electrical activity between the atria and ventricles.
True or False: The anterior cusp of the pulmonary artery is located on the posterior side.
False
Fill in the blank: The left cusp of the pulmonary artery is located on the ______ side.
right
What happens to the heart if papillary muscles are damaged?
It can lead to valve problems.
What is the normal volume ejected from the ventricle during contraction?
70 mL