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The thymus is an important organ in the immune system - VCE - SSCE Biology - Question 2 - 2011 - Paper 1
Question 2
The thymus is an important organ in the immune system. As humans grow older, there is a change in the weight of the thymus and an increase in the proportion of fat i... show full transcript
Worked Solution & Example Answer:The thymus is an important organ in the immune system - VCE - SSCE Biology - Question 2 - 2011 - Paper 1
Step 1
Explain the likely consequence of this change in thymus weight in an individual.
Answer
As individuals age, the weight of the thymus decreases significantly, which is associated with a decline in the production of T cells. This results in fewer T cells available for the immune response, leading to a reduced ability to fight infections and diseases. Consequently, older individuals may experience a weakened immune system, making them more susceptible to infections and less capable of mounting effective immune responses.
Step 2
Describe the sequence of events that would result in the red patches and blisters on Paul.
Answer
When Paul came into contact with poison ivy, he likely encountered an oil called urushiol, which is found in the plant. The initial contact triggers an immune response, where antigen-presenting cells pick up the urushiol and present it to T cells. This activates the immune system, leading to the release of inflammatory mediators. In sensitive individuals, this can result in a delayed hypersensitivity reaction that manifests as itchy red patches and blisters. The inflammation spreads from the original site of contact to other parts of the body, causing the symptoms to appear more widespread as the immune system continues to react.