Heart Structure and Valves

The double pump

The heart is really two pumps side by side. The right side sends deoxygenated blood to the lungs to collect oxygen; the left side pumps that oxygenated blood out to the whole body. Keeping blood flowing one way are the valves - and unlike some boards, Edexcel expects you to name them. This module builds the heart chamber by chamber, then follows the blood all the way round.

Inside the heart

Four structural terms come first - learn them exactly.

Match each valve to its position

What do the valves do?

What is the main job of the heart valves?

• They open one way to prevent blood flowing backwards
• They add oxygen directly to the blood
• They are the muscle that pumps the blood
• They clot the blood to stop bleeding

The pulmonary swap

A rule you half-know: arteries carry blood away from the heart, veins carry it back. Usually arteries carry oxygenated blood - but the lungs create ONE famous exception: - The pulmonary artery carries deoxygenated blood (heart to lungs).\n- The pulmonary vein carries oxygenated blood (lungs back to heart). So remember arteries by direction (away from the heart), not by oxygen. This swap is a classic exam trap.

Trace the blood

Put the journey of blood through the heart and lungs into the correct order, starting as it returns from the body.

• The vena cava brings deoxygenated blood into the right atrium
• It passes through the tricuspid valve into the right ventricle
• The pulmonary artery carries it to the lungs to collect oxygen
• The pulmonary vein returns oxygenated blood to the left atrium
• It passes through the bicuspid valve into the left ventricle
• The aorta carries oxygenated blood out to the body

The odd one out

Which vessel is unusual because it is an artery that carries deoxygenated blood?

• The pulmonary artery
• The aorta
• The pulmonary vein
• The vena cava

Arteries vs veins

The vessels are built for their jobs. Arteries handle high-pressure blood leaving the heart; veins return low-pressure blood to it.

True of arteries

Select the TWO statements that are true of arteries.

• They have thick, muscular, elastic walls
• They carry blood away from the heart
• They contain valves along their length
• They carry blood at low pressure

Match each blood component

The air path

Put the route air takes into the lungs into order, ending where gas exchange happens.

• Air passes down the trachea (the windpipe)
• It enters the two bronchi, one for each lung
• The bronchi branch into smaller bronchioles
• Air reaches the alveoli, where gas exchange happens

Blood under pressure

Three questions about blood flow in action. Pick the correct physiology each time.

• During hard exercise, how does the body deliver more blood to the working muscles (vascular shunting)?
• A heart valve becomes faulty and lets some blood leak backwards. What is the main consequence?
• Blood has just been pumped out of the right ventricle. Where does it go next?

Explain gas exchange

At the alveoli, oxygen moves into the blood and carbon dioxide moves out. Explain how gas exchange happens at the alveoli and describe the features that make them good at it.

• State which gas moves INTO the blood and which moves OUT, and name the process (diffusion)
• Explain how the large surface area of many alveoli helps
• Explain how the thin alveolar walls help
• Mention the good blood supply (capillaries) maintaining the concentration difference

Know where each valve sits

For Edexcel, two things separate top answers. First, know the valve names and where they sit - tricuspid on the right, bicuspid on the left, semi-lunar valves guarding the artery exits - because this board examines them where AQA does not. Second, be fluent in the one-way route vena cava, right atrium, right ventricle, pulmonary artery, lungs, pulmonary vein, left atrium, left ventricle, aorta - and never forget the swap: the pulmonary artery carries deoxygenated blood, the pulmonary vein carries oxygenated blood. Get those and the cardio-respiratory marks are yours.