PE- Heart Structure (DONUGHUE)

Question 1

Why is there an electrical impulse at the heart?

Answer 1

It’s myogenic, it can create its own electrical impulse

Question 2

State the 5 stages of the conduction system:

Answer 2

SA Node= generates electrical impulse and fires it through the atria walls to make them contract
AV Node= delays the impulse for 0.1 seconds to allow the atria to contract, it then sends the impulse to the Bundle of His
Bundle of His= splits the impulse into two, to be distributed into separate ventricles
Bundle Branches= carry the impulse to the ventricles
Purkyne Fibres= distribute the impulse through the ventricular walls causing them to contract

Question 3

What happens at the diastole phase?

Answer 3

Relaxation phase (0.5 seconds)
Atria + ventricles relax, they expand and absorb blood into the atria 
Pressure increases and opens AV valves 
Blood enters the ventricles 
SL valves are closed to prevent backflow

Question 4

What happens at the systole phase?

Answer 4

Contraction phase (0.3 seconds)
Atrial contract, forces remaining blood into ventricles

Question 5

What happens at ventricular systole?

Answer 5

Ventricles contract, increases pressure
Closed AV valves to prevent backflow into the atria
SL forced open as blood is ejected from the ventricles into the aorta and pulmonary artery

Question 6

What is hypertrophy?

Answer 6

When the heart gets bigger and can pump more blood

Question 7

What is bradycardia?

Answer 7

Resting HR is below 60BPM