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2.4 Heart Regulation & ECG — Test 1
Q1. Which agent stimulates the heart and reduces its ability to relax (positive inotropic and lusitropic-opposing)?✓ Sympathetic stimulation (noradrenaline)
Q2. Which of the following is NOT a unipolar lead in standard ECG recording?✓ Lead I (a bipolar limb lead)
Q3. The variation of heart rate with the breathing cycle (faster on inspiration, slower on expiration) is called:✓ Respiratory sinus arrhythmia
Q4. Baroreceptors in the carotid sinus and aortic arch respond to a rise in blood pressure by:✓ Increasing their firing, which reflexly slows the heart
Q5. The afferent (sensory) fibres from the carotid sinus baroreceptors travel in the:✓ Glossopharyngeal nerve (cranial nerve IX)
Q6. Administration of atropine (a muscarinic antagonist) to a resting person typically:✓ Increases the heart rate
Q7. The cardiovascular control centre that integrates reflex regulation of the heart is located in the:✓ Medulla oblongata
Q8. An ECG is a recording of the heart's:✓ Electrical activity
Q9. In the ECG, the PR interval mainly reflects the time for:✓ Impulse conduction from atria through the AV node to the ventricles
Q10. Sympathetic stimulation of the heart acts mainly through which receptors?✓ β₁-adrenergic receptors
Q11. Vagal (parasympathetic) stimulation of the heart causes:✓ Slowing of the heart rate (bradycardia)
Q12. A heart block (e.g. complete AV block) results from a failure of:✓ Impulse conduction between the atria and ventricles
Q13. Tachycardia refers to a heart rate that is:✓ Abnormally fast (above ~100/min in adults)
Q14. Bradycardia refers to a heart rate that is:✓ Abnormally slow (below ~60/min in adults)
Q15. A cardiac pacemaker device is used clinically to:✓ Provide regular electrical impulses when the natural conduction fails
Q16. During exercise, cardiac output is matched to demand mainly by:✓ Increased sympathetic drive raising rate and contractility
Q17. The chemoreceptors that influence heart and breathing in response to low oxygen are located in the:✓ Carotid and aortic bodies
Q18. An ECG showing absent P waves with an irregular rhythm typically indicates:✓ Atrial fibrillation
Q19. The intrinsic heart rate (with all nervous input blocked) is set by the:✓ SA node's own spontaneous firing rate