4.2 Body Defence

Front

How does pathogens enter the body?

Back

through

respiratory system

excretory system
digestive system

skin

Front

What is the function of the first line of defence in the human body?

Back

Prevents pathogens from entering the body

Front

How does the second line of defence eliminate pathogens?

Back

Through phagocytosis

Front

What happens when pathogens pass the second line of defence?

Back

They face the third line of defence

Front

What is the main function of the third line of defence?

Back

Fights pathogens by producing antibodies

Front

How do antibodies help in the third line of defence?

Back

They attach to pathogens and cause them to clump together

Front

Which substance secreted by the skin can kill microorganisms?

Back

Sweat and sebum

Front

What is the role of mucous membranes in the body’s defence system?

Back

They line the digestive and respiratory tract and trap microorganisms

Front

What does phagocytosis involve?

Back

White blood cells engulfing and digesting pathogens

Front

What is an antigen?

Back

A foreign substance that triggers the production of antibodies