Question 1: Define the term 'myocardium' and explain its role in the heart's structure.

Answer: Myocardium is the muscular tissue of the heart that enables it to contract and pump blood throughout the body.

Question 2: Describe the pathway of blood flow through the four chambers of the heart, starting from the right atrium.

Answer: Blood enters the right atrium from the vena cavae, then passes through the tricuspid valve into the right ventricle. It is pumped through the pulmonary valve into the pulmonary artery to the lungs. Oxygenated blood returns via the pulmonary veins into the left atrium, flows through the bicuspid (mitral) valve into the left ventricle, and is then pumped through the aortic valve into the aorta for circulation.

Question 3: What is the function of the atrioventricular (AV) valves in the heart?

Answer: The AV valves prevent backflow of blood from the ventricles into the atria during ventricular contraction.

Question 1: Calculate the cardiac output if a person’s stroke volume is 70 mL per beat and their heart rate is 75 beats per minute. Use the formula: Cardiac Output = Stroke Volume × Heart Rate. Express your answer in litres per minute.

Answer: 0.70 L/beat × 75 beats/min = 52.5 L/min

Question 2: If the average adult heart beats 72 times per minute and each beat ejects 80 mL of blood, what is the total volume of blood pumped in one hour? Show your calculation.

Answer: 80 mL/beat × 72 beats/min × 60 min = 345600 mL = 345.6 litres

Question 1: Describe a safe and ethical method to obtain a sample of human heart tissue for microscopic examination in a laboratory setting.

Answer: A safe method involves using ethically approved tissue samples from medical donors or cadavers, ensuring all procedures follow ethical guidelines and safety protocols such as wearing gloves, sterilising equipment, and handling tissues with care to prevent contamination or infection.

Question 2: Identify three variables that should be controlled during an experiment measuring the effect of exercise on heart rate.

Answer: Initial resting heart rate, ambient temperature, and hydration level.

Question 3: List two safety precautions to consider when conducting practical experiments involving the heart or circulatory system.

Answer: Using sterilised equipment to prevent infection and wearing protective gloves to avoid contamination and exposure to biological materials.

Question 1: A study reports that athletes have an average resting heart rate of 55 beats per minute, whereas non-athletes average 75 beats per minute. Explain what physiological adaptations might account for this difference.

Answer: Athletes often develop a stronger and more efficient heart muscle through training, which allows the heart to pump a greater volume of blood per beat (higher stroke volume). This reduces the need for a higher heart rate at rest, indicating improved cardiovascular efficiency.

Question 1: Explain how the structure of the heart's valves prevents backflow of blood during the cardiac cycle. (6 marks)

Answer: The heart's valves, such as the tricuspid, bicuspid, pulmonary, and aortic valves, are one-way valves that open to allow blood flow in a specific direction and close to prevent backflow. During ventricular contraction, these valves close tightly to ensure blood is directed out of the heart into arteries, maintaining unidirectional flow and efficient circulation.

Question 1: Discuss how advancements in medical imaging technology, such as MRI and echocardiography, have improved the study and diagnosis of heart structural abnormalities.

Answer: Advances in MRI and echocardiography allow detailed, non-invasive visualization of heart structures, enabling early detection of abnormalities such as valve defects, chamber enlargement, or congenital issues. These technologies improve diagnostic accuracy, guide treatment plans, and reduce the need for invasive procedures.