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How are the blood, blood vessels and heart adapted to transport substances around the body?

Explain how the structures of the blood, the blood vessels and the heart are related to their functions, and calculate cardiac output from stroke volume and heart rate.

A focused answer to Edexcel GCSE Biology 8.6 to 8.8 and 8.12, covering the structure and function of red and white blood cells, plasma and platelets, the blood vessels, the heart and circulation, and cardiac output calculations.

Generated by Claude Opus 4.810 min answer

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  1. What this dot point is asking
  2. The blood
  3. The blood vessels
  4. The heart and circulation
  5. Cardiac output
  6. Try this

What this dot point is asking

Edexcel statements 8.6 to 8.8 and 8.12 want you to explain how the blood, the blood vessels and the heart are adapted to their functions, and to calculate cardiac output from stroke volume and heart rate.

The blood

The blood vessels

The heart and circulation

The heart is a muscular double pump that circulates blood in two loops:

  • The right side pumps deoxygenated blood to the lungs to be oxygenated (the pulmonary circuit).
  • The left side pumps oxygenated blood to the rest of the body (the systemic circuit). The left side has a thicker, more muscular wall because it must pump at higher pressure to reach the whole body.

Blood enters the upper chambers (atria) and is pumped out by the lower chambers (ventricles). Valves between and leaving the chambers keep blood flowing one way. The major vessels include the aorta (to the body), the vena cava (from the body), the pulmonary artery (to the lungs) and the pulmonary vein (from the lungs).

Cardiac output

Stroke volume is the volume of blood pumped out by the heart in one beat; heart rate is the number of beats per minute. Cardiac output is the total volume pumped per minute, so it rises during exercise as both stroke volume and heart rate increase.

Try this

Q1. State the function of platelets and of plasma. [2 marks]

  • Cue. Platelets help the blood clot at a wound; plasma is the liquid that transports cells, dissolved food, carbon dioxide, urea and hormones.

Q2. A heart has a stroke volume of 70 cm370\ cm^{3} and a heart rate of 6060 beats per minute. Calculate the cardiac output. [2 marks]

  • Cue. Cardiac output =70×60=4200 cm3= 70 \times 60 = 4200\ cm^{3} per minute (4.24.2 litres per minute).

Exam-style practice questions

Practice questions written in the style of Pearson Edexcel exam questions on this dot point, with worked answer explainers. The year tag is the paper they imitate, not the source.

Edexcel 20194 marksExplain how a red blood cell is adapted to its function of carrying oxygen.
Show worked answer →

A 4-mark explain question rewards adaptations each linked to carrying oxygen.

  1. A red blood cell is packed with haemoglobin, the red pigment that binds oxygen, so it can carry a large amount of oxygen.
  2. It has no nucleus, leaving more room for haemoglobin.
  3. It has a biconcave disc shape, which gives a large surface area to volume ratio for fast diffusion of oxygen in and out.
  4. Being small and flexible, it can squeeze through narrow capillaries to deliver oxygen to tissues.

Markers reward haemoglobin binding oxygen, no nucleus for more haemoglobin, and the biconcave shape giving a large surface area. A bare description of the shape, without linking it to oxygen transport, scores less.

Edexcel 20213 marksA person has a heart rate of 70 beats per minute and a stroke volume of 80 cm380\ \text{cm}^3. Calculate their cardiac output and give the unit.
Show worked answer →

A 3-mark calculation rewards the correct equation, substitution and unit.

Cardiac output == stroke volume ×\times heart rate =80×70=5600 cm3= 80 \times 70 = 5600\ cm^{3} per minute.

Markers reward the correct equation, the value 56005600, and the unit cm3cm^{3} per minute (or ml/min). Multiplying the wrong quantities, or leaving off the per-minute unit, loses marks. The answer can also be written as 5.65.6 litres per minute.

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