Fighting Disease

Question 1

Describe the function of the physical and chemical defences of the human body.

Answer 1

To stop pathogens entering the body

Question 2

Give some examples of physical barriers of the human body.

Answer 2

• The skin acts as a barrier to pathogens
• Hairs and mucus in your nose trap particles that could contain pathogens

Question 3

(Exam-style question)

Answer 3

Question 4

Give some examples of chemical barriers of the human body.

Answer 4

• The stomach produces hydrochloric acid, which kills most pathogens that are swallowed
• The eyes produce lysozyme enzymes (in tears) which kill bacteria on the surface of the eye

Question 5

State what is meant by the term ‘specific immune response’.

Answer 5

The immune response to a specific pathogen

Question 6

The most important part of your immune system is the white blood cells.

Describe the function of white blood cells.

Answer 6

To travel around your blood and patrol for pathogens

Question 7

What are B-lymphocytes?

Answer 7

A type of white blood cell that is involved in the specific immune response

Question 8

What are antigens?

Answer 8

The proteins on the surface of pathogens

Question 9

(Exam-style question)

Explain how B-lymphocytes help the body to fight against invading pathogens.

Answer 9

• B-lymphocytes detect antigens on a pathogen in the blood
• The B-lymphocytes produce specific antibodies, which bind to the pathogen and destroy it
• The antibodies are then produced rapidly and flow throughout the body to find all similar pathogens