Cardiac Physiology

Here are simplified flashcard-style notes based on your “Cardiac Physiology” PDF. You can use them for quick review or as a physical/online flashcard set:

MUSCLE TISSUE

Q: What are the 3 types of muscle tissue?
A: Cardiac, Skeletal, Smooth

Q: What are the 4 traits all muscle tissues share?
A: Irritability, Contractility, Extensibility, Elasticity

CARDIAC VS SKELETAL MUSCLE

Q: What connects cardiac muscle cells?
A: Intercalated discs

Q: Why don’t cardiac muscles get fatigued like skeletal muscles?
A: They contract longer and don’t go into tetanus.

Q: Why is calcium important in cardiac muscle?
A: It triggers contractions.

Q: Are cardiac cells electrically linked?
A: Yes, for synchronized contraction.

CONDUCTION SYSTEM BASICS

Q: Is the heart myogenic or neurogenic?
A: Myogenic – it beats on its own.

Q: What is the SA Node?
A: Natural pacemaker of the heart; sets rhythm (~70–80 bpm).

Q: What makes the heart beat without nerves?
A: Autorhythmic cells leak ions and depolarize on their own.

ELECTRICAL PATHWAY

Q: Trace the electrical path through the heart.
A: SA Node → AV Node → Bundle of His → R/L Bundle Branches → Purkinje Fibers

Q: What does the AV Node do?
A: Delays the impulse to let atria contract before ventricles.

Q: What do Purkinje fibers do?
A: Spread signal through ventricles for synchronized contraction.

PACEMAKER BACKUPS

Q: What happens if the SA node fails?
A: AV node or Purkinje fibers take over (ectopic pacemakers), but slower.

NERVOUS INFLUENCE

Q: What does the sympathetic nervous system do to HR?
A: Speeds it up.

Q: What does the parasympathetic nervous system do to HR?
A: Slows it down (mainly via vagus nerve).

ECG BASICS

Q: What does an ECG measure?
A: Electrical activity (not contraction)

Q: What do these ECG waves represent?

• P Wave = Atrial depolarization

• QRS Complex = Ventricular depolarization

• T Wave = Ventricular repolarization

ELECTRICAL CELL TYPES

Q: What are the 3 electrical cell types in the heart?
A: Nodal (starts signal), Conductile (spreads it), Contractile (contracts)

Q: What’s special about nodal cells?
A: Unstable RMP, self-depolarizing

Q: What’s special about contractile cells?
A: Stable RMP, sharp AP spike, long plateau for strong contraction

DYSRHYTHMIAS

Q: Where do supraventricular arrhythmias start?
A: SA node, AV node, or atria

Q: Where do ventricular arrhythmias start?
A: Bundle of His, bundle branches, Purkinje fibers, or ventricles

Q: Which is more dangerous: supraventricular or ventricular arrhythmias?
A: Ventricular (e.g., ventricular fibrillation)

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