The heart and blood vessels

The heart

Components of the heart

• Valves - Bicuspid, tricuspid, semi-lunar
• Tendinous chords and papillary muscles to keep valves closed/open
• Aorta, Pulmonary artery - Away from the heart
• Pulmonary vein, vena cava - to the heart
• Atria- top chambers, thin
• Ventricles - Bottom chambers, thicker, left is thickest.

The cardiac cycle

Diastole:

The heart is relaxed, AV valves are open and blood is trickling through the atria into the ventricles.

Atrial systole:

Atria begin to contract, pushing all the blood out of the atria into the ventricles, the walls of the ventricles stretch to ensure they are full of blood. Blood fills the av valve flaps causing them to shut.

Ventricular systole:

For a brief moment all of the valves are shut, then the ventricles begin to contract starting from the apex, the pressure raises in the ventricles and blood is pushed up towards the arteries…