Chronotropy

Question 1

What are the major determinants of cardiac output?

Answer 1

Heart rate
Preload
Myocardial contractility
Afterload

Question 2

Where is the Sinoatrial Node located?

Answer 2

Aka the primary pacemaker of the heart

Located in the wall of the right atrium near the entry of the cranial vena cave

Question 3

What is the name of the pacemaker with the second highest inherent rate?

Answer 3

Atrioventricular node

Question 4

Describe the normal order of conduction through the heart

Answer 4

SA Node
Atria
AV Node
Purkinje system 
Ventricular muscle

Question 5

What are the functions of the cardiac skeleton?

Answer 5

To help provide structural integrity to the heart

To break up the continuity between cardiac muscle cells of the atria from those of the ventricles

Question 6

What innervation does the vagus nerve provide?

Answer 6

Parasympathetic - innervates SA and AV nodes; small amount to atria

Question 7

What provides sympathetic innervation to the SA and AV nodes, atria and ventricles?

Answer 7

Adrenergic fibres

Question 8

What innervation is dominant at rest?

Answer 8

Parasympathetic (Vagus)

Question 9

How can heart rate be increased?

Answer 9

Decreasing vagal tone

Increasing sympathetic tone

Question 10

Draw a graph to illustrate a ventricular action potential

Answer 10

Phase 4: resting membrane potential
Phase 0: rapid depolarisation caused by the opening of fast sodium channels
Phase 1: known as the Notch; occurs as fast sodium channels close
Phase 2: plateau caused by the slow inward current of calcium and outward current of potassium
Phase 3: Repolarisation as the inward current of calcium inactivates and the outward current of potassium dominates