Cardiovascular System

WJEC

GCSE

Analyze the mechanics of the cardiac cycle, including the conduction system (SAN, AVN, Bundle of His, Purkinje fibres) and the regulation of heart rate via the autonomic nervous system. Evaluate the acute responses to exercise, specifically the vascular shunt mechanism and the redistribution of cardiac output (Q) to working muscles. Contrast these with chronic adaptations such as cardiac hypertrophy, bradycardia, and increased capillarisation resulting from aerobic training. Apply Starling's Law to explain stroke volume changes during varying intensities of physical activity.

Objectives

Exam Tips

Pitfalls

Key Terms

Mark Points

What You Need to Demonstrate

Key skills and knowledge for this topic

Award marks for the correct application of the equation: Cardiac Output (Q) = Stroke Volume (SV) x Heart Rate (HR).
Credit identification of the specific pathway of blood: Vena Cava -> Right Atrium -> Right Ventricle -> Pulmonary Artery.
Responses must explain the vascular shunt mechanism: Vasodilation of arterioles supplying working muscles and vasoconstriction of arterioles supplying non-essential organs.
Differentiate vessel characteristics: Arteries (thick muscular walls, high pressure), Veins (valves to prevent backflow, wide lumen), Capillaries (one cell thick for gaseous exchange).

Example Examiner Feedback

Real feedback patterns examiners use when marking

"Precise terminology required: replace generic terms like 'tubes' with 'arterioles' or 'capillaries' to access higher mark bands."
"Show your working for the Cardiac Output calculation; method marks are available even if the final value is incorrect."
"Develop your analysis of the vascular shunt mechanism by explicitly mentioning the role of pre-capillary sphincters."
"Link the structural adaptation (hypertrophy) directly to the functional benefit (increased stroke volume) in the context of the athlete."

Marking Points

Key points examiners look for in your answers

Award marks for the correct application of the equation: Cardiac Output (Q) = Stroke Volume (SV) x Heart Rate (HR).
Credit identification of the specific pathway of blood: Vena Cava -> Right Atrium -> Right Ventricle -> Pulmonary Artery.
Responses must explain the vascular shunt mechanism: Vasodilation of arterioles supplying working muscles and vasoconstriction of arterioles supplying non-essential organs.
Differentiate vessel characteristics: Arteries (thick muscular walls, high pressure), Veins (valves to prevent backflow, wide lumen), Capillaries (one cell thick for gaseous exchange).

Examiner Tips

Expert advice for maximising your marks

💡When calculating Cardiac Output from a data table, ensure units are consistent (e.g., converting ml to L if required).
💡In 6-mark extended responses, link structural features (e.g., valves) directly to their function (preventing backflow) within the context of the specific sport.
💡Memorize the sequence of the cardiac cycle (Diastole/Systole) to accurately describe the filling and ejection phases.

Common Mistakes

Pitfalls to avoid in your exam answers

Confusing the Pulmonary Artery (deoxygenated blood) with the Pulmonary Vein (oxygenated blood).
Attributing vasodilation and vasoconstriction to 'veins' or 'arteries' generally, rather than specifically to 'arterioles' or 'pre-capillary sphincters'.
Defining Stroke Volume vaguely as 'blood pumped' without specifying 'per beat' or 'from the left ventricle'.

Key Terminology

Essential terms to know

Cardiac Conduction System & Neural Control

Vascular Shunt Mechanism & Vasomotor Control

Acute Responses vs. Chronic Adaptations

Hemodynamics & Blood Pressure Regulation

Likely Command Words

How questions on this topic are typically asked

Identify

Explain

Calculate

Analyse

Evaluate

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