The Cardiovascular System

Diastole

The period when the ventricles and atria are relaxed, allowing blood flow. The AV valves are open, allowing blood to flow from the atria into the ventricles.

Systole

The period when the ventricles are contracting, increasing pressure and forcing blood out of the heart through the semilunar valves.

Cardiac System

The pumping of the cardiac muscle allowing blood to flow. It is controlled by electrical impulses

5 parts of the conduction system (in order)

Sinoatrial node -- Atrioventricular node -- Bundle of His -- Left and right bundle branches -- Purkinje fibres

Stage 1 of the conduction system

The SA node sends an impulse across the atria which stimulates them to contract

Stage 2 of the conduction system

The impulse arrives at the AV node, where it is delayed, allowing the ventricles to fully fill with blood

Stage 3 of the conduction system

The impulse travels down the bundle of His located in the septum

Stage 4 of the conduction system

The impulse travels along the Purkinje fibres which branch along the base of the right and left ventricles and cause the ventricles to contract

Myogenic

The SA node generates its own impulse

Journey of electrical impulses

The impulse goes from the SA node to the left atrium and then to the AV node

Oxyhaemoglobin

one haemoglobin molecule carries 4 oxygen molecules, which is transported to the tissues where oxygen is released

Myoglobin

stores oxygen in muscle cells

Health benefits of sports and activity (3)

• Prevents heart disease by increased blood circulation
• Reduces high cholesterol by decreasing weight
• Prevents a stroke by decreasing blood pressure

FItness benefits of sport and activity (2)

• Cardiac output increases due to cardiac hypertrophy
• Improved components of fitness

How the heart rate is controlled by the Autonomic Nervous System (2 chains)

• Cardiac control centre (ANS) -> parasympathetic NS -> Via vagus nerve to -> SA node

• CCC (ANS) -> sympathetic NS -> VIa accelerator nerve to -> SA node

sympathetic nerves

autonomic nerves that increase heart rate and stroke volume

parasympathetic nerves

autonomic nerves that decrease heart rate and stroke volume