OCR A-Level PE applied anatomy and physiology: a complete overview of Component 01 Section A

What this section demands

Applied anatomy and physiology is Section A of Component 01. It is the foundation of the whole physiological paper: the body systems that supply oxygen and energy, recruit muscle and produce movement. The exam tests precise recall of structures and mechanisms, two key calculations (cardiac output and minute ventilation), and the ability to apply fibre types and energy systems to a named sport. This overview ties the dot-point pages together.

The skeletal and muscular systems

Synovial joints (hinge, ball and socket, condyloid, pivot) allow movements such as flexion, extension, abduction, adduction and rotation. Movement is produced by antagonistic muscle action: the agonist shortens, the antagonist relaxes and lengthens, and a fixator stabilises. Contractions are concentric (shortening under tension), eccentric (lengthening under tension) or isometric (no change in length). The three fibre types (Type I, Type IIa, Type IIx) trade fatigue resistance for speed and power. See the skeletal and muscular systems page.

The cardiovascular system

The heart pumps in a cardiac cycle driven by the SA node, AV node, bundle of His and Purkinje fibres. Cardiac output is $Q = HR \times SV$ and rises in exercise. Venous return is maintained by the skeletal muscle pump, respiratory pump, pocket valves, smooth muscle and gravity, and the Starling effect turns more venous return into more stroke volume. The vascular shunt redistributes blood to the working muscles, and cardiovascular drift raises heart rate as plasma volume falls. See the cardiovascular system page.

The respiratory system

Breathing changes the volume of the thorax; expiration is passive at rest but active in exercise. Minute ventilation is $V_E = TV \times f$. Gaseous exchange happens by diffusion down partial-pressure gradients at the alveoli and the muscles, and the Bohr shift (the oxyhaemoglobin curve moving right as temperature and carbon dioxide rise and pH falls) increases oxygen unloading at the muscle. See the respiratory system page.

The neuromuscular system

A motor unit is one motor neuron plus its fibres, and the all-or-none law means every fibre in a unit contracts maximally or not at all. Force is graded by recruiting more units (spatial summation) and by wave summation (temporal summation). Muscle spindles detect stretch (a protective contraction) and Golgi tendon organs detect tension (a protective relaxation used in PNF stretching). See the neuromuscular system page.

The energy systems

ATP is the energy currency, resynthesised by three systems: the ATP-PC system (phosphocreatine, fast, no fatiguing by-product, up to about 10 seconds), the anaerobic glycolytic system (glucose, 2 ATP, lactate and hydrogen ions, up to 3 minutes), and the aerobic system (glucose and fats with oxygen, 36 to 38 ATP, carbon dioxide and water, prolonged exercise). The energy continuum means all three contribute, set by intensity and duration. See the energy systems and ATP page.

Check your knowledge

Attempt these, then check the solutions.

1. A performer has a heart rate of 75 beats per minute and a stroke volume of 80 ml. Calculate their cardiac output and state the unit. (2 marks)
2. Name the contraction type used by the biceps when lowering a weight slowly, and explain why. (2 marks)
3. Which fibre type suits a 100 m sprinter, and give two of its characteristics? (3 marks)
4. State the fuel and the main fatiguing by-product of the anaerobic glycolytic system. (2 marks)
5. Explain in one sentence why a cool-down maintains venous return. (2 marks)