Cardiovascular System

Question 1

Stage 1 of cardiac conduction system

Answer 1

1) The heart is myogenic, generating its own electrical impulses making it contract by a group of cells in the walls of the atria called the sinoatrial node (SAN)

Question 2

Stage 2 of the cardiac conduction system:

Answer 2

2) Impulses generated from the sinoatrial node spread across both atria, causing contraction

Question 3

Stage 3 of the cardiac conduction system

Answer 3

The impulse reaches the atrioventricular node (AVN) which delays the contraction for 0.1s allowing Atria to contract fully (atrial systole)

Question 4

Stage 4 of the cardiac conduction system

Answer 4

Once atrial systole occurred, impulse passes down the septum of the heart to the bundle of his, which pass contraction into the bundle of his, into the Purkinje fibres. These spread the impulse in the myocardium surrounding the ventricles, causing contraction.

Question 5

Where is the medulla oblongata located

Answer 5

In the cardiac conduction centre

Question 6

Venous return

Answer 6

The return of blood to the right side of the vena cava.

Question 7

Mnemonic for cardiac conduction system

Answer 7

Sally, always, aims, balls, past, vicky
SAN, atrial systole, AVN, Bundle of His, Purkinje fibres, Ventricular systole

Question 8

Discuss how the cardiac conduction system works?

Answer 8

The heart is said to be myogenic because it has the ability to generate its own electrical impulses which originate in the heart muscle itself with an electrical signal in the SAN. This impulse spreads across the heart like a wave of excitation, causing atrial systole or the atria to contract. The impulse them passes to the AVN and is delayed for 0.1s while atrial systole occurs and filling of atria. The impulse then travels down the bundle of His which then divides into 2 branches and then again into the purkinje fibres. This allows the impulse to spread throughout the ventricles causing them to contract- this is ventricular systole.

Question 9

SV in untrained individual, trained and elite endurance

Answer 9

Untrained= 112ml
Trained= 130ml
Elite= 180ml

Question 10

Long term effects of exercise on the heart

Answer 10

-cardiac hypertrophy (heart muscles get bigger and more blood ejected per beat increased SV/CO, decreased RHR)
-bradycardia (resting hr below 60bpm)