Session 2 - The Heart As A Pump

Question 1

Which Valve separates the Right Atria and Ventricle?

Answer 1

The Tricuspid Valve

Question 2

Which valve seperates the Left Atrium and Ventricle?

Answer 2

The Mitral Valve

Question 3

Which valve prevents back flow into the Left Ventricle?

Answer 3

The Aortic Valve

Question 4

Which valve prevents back flow into the Right Ventricle?

Answer 4

The Pulmonary Valve

Question 5

Name some histological features of cardiac muscle?

Answer 5

• Striated
• Branching fibres
• Centrally positioned nuclei
• Intercalated discs and Gap Junctions
• T-tubules in line with Z-line

Question 6

What is Systole?

Answer 6

The period of the cardiac cycle in which ventricles contract to eject blood

Question 7

What is Diastole?

Answer 7

The period of the cardiac cycle in which the ventricles are filled

Question 8

Describe the spread of electrical excitation through the heart in Systole?

Answer 8

• SA nodes fires an AP which spreads over the Atari causing contraction, AP then delayed at the AVN for 120ms
• AP then spreads down septum between ventricles and spreads from endocardial surface to epicardial
• Ventricles contract from apex out

Question 9

How is the ventricular muscle organised? And why is this important?

Answer 9

Figure of eight bands

Squeezes the ventricular chamber forcefully in a way most effective for ejection

Question 10

Name two differences between the Left and Right heart muscle

Answer 10

1 - LHS has thicker myocardium (has to pump blood to whole body not just lungs)
2 - RHS has the Sino-atrial node within it

Question 11

What happens in Phase 1 - Atrial Contraction of the cardiac cycle?

Answer 11

• Atrial contraction fills last 10% of ventricles
• The Mitral and Tricuspid valves open

Responsible for P-wave of ECG

Question 12

What happens in Phase 2 - Isovolumetric Contraction of the cardiac cycle?

Answer 12

• Closure of Mitral and Tricuspid valves (First heart sound)
• No valves now open
• Ventricular pressure greatly increases

Responsible for QRS complex of ECG

Question 13

What happens in Phase 3 - Rapid Ejection of the cardiac cycle?

Answer 13

• Intraventricular pressure > aorta and pulmonary arteries
• Valves open
• Rapid ejection occurs
• Atria also fill

Question 14

Whic blood vessel supplies blood to the Right Atrium?

Answer 14

The Vena Cavae - Both the Superior and Inferior

Question 15

What happens in Phase 4 - Reduced Ejection of the cardiac cycle?

Answer 15

• Ventricles repolarize and hence pressure decreases
• Rate of ejection decreases
• Atrial pressure slowly increases

Question 16

What happens in Phase 5 - Isovolumetric relaxation of the cardiac cycle?

Answer 16

• Ventricular pressure

Question 17

What happens in Phase 6 - Rapid Filling of the cardiac cycle?

Answer 17

• Atrial pressure > Ventricular
• Mitral and Tricuspid valves open
• Rapid increase in ventricular volume

May cause a third sound in children or as a sign of pathology in adults

Question 18

What happens in Phase 7 - Reduced Filling of the cardiac cycle?

Answer 18

• Filling slows as ventricles reach maximum volume