AF Anatomy & Physiology Fundamentals 2

Question 1

Which layer of the heart wall contains the specialized conduction tissue responsible for impulse propagation?

Accepted Answer

Myocardium

Answer

The myocardium contains both working cardiomyocytes and the specialized conduction fibers (Purkinje fibers) that propagate electrical impulses.

Question 2

The coronary sinus drains deoxygenated blood from the myocardium into which cardiac chamber?

Accepted Answer

Right atrium

Answer

The coronary sinus empties deoxygenated blood from the coronary circulation directly into the right atrium.

Question 3

Which autonomic receptor type, when stimulated, slows the heart rate by increasing potassium conductance in SA nodal cells?

Accepted Answer

M2 muscarinic

Answer

M2 muscarinic receptors activate GIRK channels, increasing K+ outflow and hyperpolarizing SA nodal cells to slow the heart rate.

Question 4

The fibrous skeleton of the heart serves what primary function relevant to atrial fibrillation?

Accepted Answer

Electrically insulates the atria from the ventricles

Answer

The fibrous skeleton acts as an electrical barrier, ensuring atrial impulses can only reach the ventricles through the AV node.

Question 5

Stretch of atrial myocytes due to increased filling pressure promotes AF through which mechanism?

Accepted Answer

Shortening of atrial effective refractory period

Answer

Mechanical stretch activates stretch-sensitive ion channels that shorten the atrial effective refractory period, promoting reentrant circuits.

(AF) Atrial Fibrillation Certification Practice Test