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The volume of blood that the heart pumps with every beat is known as the stroke volume - Edexcel - GCSE Biology - Question 4 - 2012 - Paper 1
Question 4
The volume of blood that the heart pumps with every beat is known as the stroke volume. Stroke volume can be used to indicate fitness level. The table gives informa... show full transcript
Worked Solution & Example Answer:The volume of blood that the heart pumps with every beat is known as the stroke volume - Edexcel - GCSE Biology - Question 4 - 2012 - Paper 1
Step 1
Calculate the stroke volume of the athlete during exercise.
Answer
To calculate the stroke volume during exercise, we use the formula for cardiac output:
Given:
- Cardiac Output = 30.4 dm³ min⁻¹
- Heart Rate = 182 beats per minute
We rearrange the formula to find the stroke volume:
So, the stroke volume of the athlete during exercise is approximately 0.167 dm³.
Step 2
Explain why it is important that the cardiac output of the athlete increases during exercise.
Answer
The increase in cardiac output during exercise is crucial for several reasons:
- Increased Muscle Activity: Muscles require more energy to sustain heightened activity levels, which translates to an increased demand for oxygen and nutrients.
- Enhanced Oxygen Delivery: The heart pumps faster and more forcefully, allowing for a quicker delivery of oxygen to active tissues, particularly muscles that contract harder and faster during exercise.
- Efficient Waste Removal: Increased cardiac output facilitates faster removal of metabolic waste, such as carbon dioxide and lactic acid, which builds up during intense physical activity, preventing fatigue.
Step 3
Describe how the circulatory system transports substances around the body.
Answer
The circulatory system efficiently transports substances through a network of blood vessels:
- Arteries/Aorta: Blood is pumped away from the heart through arteries, which convey oxygen-rich blood to the body.
- Veins/Vena Cava: Veins return deoxygenated blood back to the heart through the vena cava.
- Capillaries: These tiny blood vessels allow for the exchange of gases, nutrients, and waste between blood and tissues. Substances like oxygen and glucose are delivered, while carbon dioxide and other wastes are collected for removal.
- Plasma and Red Blood Cells: Blood plasma carries substances, and oxygen is specifically transported by red blood cells, enhancing the overall efficiency of nutrient and gas exchange.