Heart structure — the parts to identify
Muscular wall — cardiac muscle contracting to pump, thickest in the left ventricle. Septum — the internal wall between the sides, keeping oxygenated and deoxygenated blood apart. Atria — thin-walled upper chambers taking blood from veins. Ventricles — thick-walled lower chambers pumping blood out. One-way valves — passive flaps stopping backflow. Coronary arteries — aorta branches serving the heart muscle. Blood leaves in arteries, returns in veins.
(Extended) The cardiac cycle — atria, then ventricles
(Supplement) The atria contract first, forcing blood through the valves into the ventricles. The ventricles then contract and pressure inside them rises: once it exceeds atrial pressure the atrioventricular valves close, stopping backflow; once it exceeds aorta/pulmonary artery pressure the exit valves open and blood is forced out. Only the atrial and ventricular walls are muscular — the valves move passively, driven by the pressure difference across them.
Coronary heart disease and its risk factors
Coronary heart disease (CHD) is the narrowing or blockage of the coronary arteries by fatty deposits, cutting the supply of oxygenated blood to the heart muscle. Seven possible risk factors are named: diet, lack of exercise, stress, smoking, genetic predisposition, age and sex. A diet low in saturated fat and salt reduces the fatty deposits that narrow the arteries; regular exercise strengthens the heart muscle, helps control body mass and reduces stress.
Drawn from real examiner reports.
Septum ≠ aorta or vena cava
The septum is the internal muscular wall running down the middle of the heart, separating left from right. It is not a blood vessel: the aorta leaves the left ventricle and the vena cava enters the right atrium, and both lie outside the chambers. Nor is it a valve — the septum is fixed and permanent, a valve is a movable flap.
Flagged Jun 2022 P31 Q1biii
Name the vessel, not just "an artery"
When a question asks which vessel carries blood into or out of a chamber, only the specific name scores: pulmonary artery, pulmonary vein, aorta or vena cava. The vessel leaving the right ventricle is the pulmonary artery; the vessel entering the right atrium is the vena cava. The general term says what a vessel does, not which one it is.
Flagged Jun 2022 P31 Q1c; P32 Q7c
Diet excluded — give another factor
CHD has seven named risk factors: diet, lack of exercise, stress, smoking, genetic predisposition, age and sex. If a question asks for factors other than diet, the answer must come from the remaining six. Rewording diet ("eating too much fat") is still a diet answer and scores zero. Learn all seven as a fixed list.
Flagged Jun 2022 P42 Q1bi · Nov 2023 P43 Q1a
Heart diagrams are left-right reversed
A heart diagram is drawn from the patient's point of view, so the LEFT side of the heart appears on the RIGHT of the page. Labelling it as if viewed from the front reverses every left/right label at once — left ventricle, right atrium and both named vessels all end up wrong. Check the thick-walled ventricle: that side is the left.
Atria receive, ventricles pump
Atria are the two upper chambers, thin-walled; they receive blood arriving from the veins. Ventricles are the two lower chambers with thick muscular walls; they pump blood into the arteries. The left ventricle wall is the thickest of the four, because it pumps at the highest pressure — round the whole body. Drawing both ventricle walls equally thick loses the mark.
ECG is electrical, pulse is mechanical
An ECG (electrocardiogram) records the heart's electrical activity, showing its rhythm and timing. A pulse is the mechanical stretching of an artery wall as a surge of blood passes, felt where an artery lies near the skin. Listening to the valves closing with a stethoscope is a third, separate method. All three monitor the heart, but they measure different things.
Coronary artery ≠ coronary heart disease
A coronary artery is a normal, healthy vessel branching from the aorta and running over the outside of the heart to supply the heart muscle. Coronary heart disease is what happens when one becomes narrowed or blocked by fatty deposits. The disease affects the artery; it is not itself a structure. Do not confuse coronary arteries with the aorta or pulmonary artery.
(Extended) Explain means give the whole chain
(Supplement) "Heart rate increases" is a description, not an explanation. Give the chain: exercising muscles respire faster → more carbon dioxide is produced and detected → signals raise the rate and force of contraction → oxygen and glucose reach the muscles faster.
(Extended) Always reason from pressure
(Supplement) A valve opens when the pressure behind it exceeds the pressure ahead of it, and closes when that reverses. For blood to leave the heart, ventricle pressure must exceed aorta pressure. Valves never open by their own muscle action.
Match your points to the mark tariff
Give as many separate points as there are marks — a 3-mark explain needs three linked steps, not one idea restated. Always attach units to a numerical answer (heart rate in beats/minute), and convert the counting time into minutes before dividing.
Label valves at both positions
A heart diagram needs valves marked in two places: between each atrium and its ventricle, and at the exit of each ventricle. Candidates routinely omit the exit valves. Draw them as flaps, and label coronary arteries as small vessels on the outer surface.
Define the septum of the heart and state its function.
During vigorous exercise, a runner counts pulses at the wrist over a -second period.
Calculate the runner's heart rate in beats per minute.
