Unit 2.6 The Strcuture And Function Of The Heart

Question 1

What is diastole?

Answer 1

• blood enters the atria via the vena cavae and pulmanory veins
• the heart is relaxed, all valves are closed
• until the blood pressure in the atria exceeds the bp in the ventricles
• then the AV valves open, allowing blood to enter the ventricles

Question 2

What is artial systole?

Answer 2

• Left & Right atria contract to force blood from the atria into the ventricles
• the ventricles, still relaxed, fill up with blood and pressure increases
• the AV valves then close to prevent backflow of blood from the ventricles to the atria

Question 3

What is ventricular systole?

Answer 3

• ventricles then contract, the pressure exerted opens the SL valves
• This allows blood to be pushed into the aorta and pulmanory artery
• Once the ventricle empties, SL vlaves close and the heart relaxes

Question 4

What creates the “lubb” noise

Answer 4

The closing of the AV vlaves

Question 5

What causes the “dupp” sound

Answer 5

Closing of the SL valves

Question 6

What is the SAN node

Answer 6

The pacemaker of the heart

Question 7

What is the function of the SAN node?

Answer 7

It initates electrical impulses which spread across the atria to make cardiac muscle contract , stimulating atrial systole

Question 8

What is the function of the AV node?

Answer 8

The AV node passes the signal from the SAN down conducting fibres which stimuates ventricular systole