ATI RN
Cardiovascular System Questions Questions
Question 1 of 5
Effect on force of contraction of heart is:
Correct Answer: D
Rationale: Inotropic effect (D) alters contraction force (e.g., via calcium). Chronotropic (A) is rate, dromotropic (B) conduction, bathmotropic (C) excitability.
Question 2 of 5
Which structure in the heart initiates action potentials that stimulate contraction of the heart at constant rate of about 100 beats per minute?
Correct Answer: D
Rationale: The SA node (D) initiates action potentials at ~100 bpm, though vagal tone slows it to 60-80 bpm in vivo. AV node (B) is slower (~40-60 bpm), nerves (A) and center (C) modulate.
Question 3 of 5
All of the following will increase heart rate except:
Correct Answer: C
Rationale: Parasympathetic stimulation (C) (vagus nerve) slows heart rate; others increase it via sympathetic or reflex mechanisms.
Question 4 of 5
The tough, loose-fitting outer layer of the sac covering the heart
Correct Answer: C
Rationale: The parietal pericardium (C) is the tough outer layer of the pericardial sac. Epicardium (A) and visceral pericardium (B) are on the heart, myocardium (D) is muscle.
Question 5 of 5
The amount of blood that flows out of a ventricle per unit of time
Correct Answer: B
Rationale: Cardiac output (B) is the total blood volume ejected from a ventricle per minute (stroke volume × heart rate). Stroke volume (A) is per beat, heart rate (C) is beats, afterload (D) is resistance.