The diagram represents a section of human skin punctured by a splinter of wood - Scottish Highers Human Biology - Question 13 - 2019
Question 13
The diagram represents a section of human skin punctured by a splinter of wood.
a) (i) Describe one way in which these epithelial cells defend the body against path... show full transcript
Worked Solution & Example Answer:The diagram represents a section of human skin punctured by a splinter of wood - Scottish Highers Human Biology - Question 13 - 2019
Step 1
Describe one way in which these epithelial cells defend the body against pathogens.
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Answer
Epithelial cells act as a physical barrier to pathogens, preventing them from entering the body.
Step 2
Name structure X.
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Answer
The name of structure X is blood capillary.
Step 3
Name the cells that release histamine.
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Answer
The cells that release histamine are mast cells.
Step 4
Explain why the skin around a puncture wound often becomes red and swollen.
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Answer
The skin becomes red and swollen due to vasodilation and increased blood flow to the area, resulting from the release of histamine. This leads to an accumulation of fluid in the tissues.
Step 5
Explain how a lymphocyte is able to recognise a particular pathogen.
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A lymphocyte recognises a particular pathogen by identifying specific antigens present on the pathogen's surface. It has specific receptors that bind to these antigens.
Step 6
Describe how T lymphocytes destroy infected body cells.
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T lymphocytes destroy infected body cells by inducing apoptosis or programmed cell death. They release enzymes that trigger self-destructive pathways in the infected cells.
Step 7
Suggest a reason for the decrease in HIV concentration during the first year after infection.
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The decrease in HIV concentration during the first year is likely due to the immune response, including the activation of T lymphocytes that target and attack the HIV virus.
Step 8
Explain why the T lymphocyte concentration is decreasing between 1 and 5 years after infection.
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The T lymphocyte concentration decreases between 1 and 5 years after infection because the virus continuously replicates and destroys T lymphocytes, weakening the immune response.
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