Question

Which statement describes many of the structures involved in the first line of defense of the immune system? They have contact with the external environment. They are internal and contact the pathogen through blood. They produce B-cells in response to a pathogen. They produce T-cells in response to a pathogen.

Answer 1

Answer:

The correct answer would be They have contact with the external environment.  

The first line of defense refers to the outside defense system which consists of physical and chemical barriers.

They have contact with the external environment and help in preventing the entry of the infectious agent in the body.

They include skin, mucous membranes and their secretions such as tears, stomach acid, urine flow, et cetera.

Answer 2

The first line of defence refers to the outside defense system which they have contact with the external environment.The correct answer would be They have contact with the external environment.  

What is the first line of defence?

The first line of defence contains physical and chemical barriers that are always keen and organised to defend the body from infection. These contain skin, tears, mucus, cilia, stomach acid, urine flow, etc.

Thus, they have contact with the external environment, they have contact with the external environment.

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