21.2

The immune system

• Helps the body to defend against infectious organisms and other invaders

• enables us to cope with and process our emotions

• Helps us to digest food

• Helps people to sense their surroundings

The first line of defense helps to

• prevent pathogens from entering body

• fight pathogens once they have entered the body

• remember pathogens that have previously invaded

White blood cells which recognize foreign pathogens, produce antibodies, and tag the pathogen for destruction are

• T-cells

• B-cells

• phagocytes

• hemoglobin

Long-term immunity resulting from exposure to a pathogen and thus antibodies production is called

• passive immunity

• herd immunity

• active immunity

• real immunity

Each of the following is a type of white blood cells EXCEPT

• B-cells

• phagocytes

• T-cells

• lymphocytes

• All of the above are types of white blood cells

White blood cells which attack and destroy any pathogen, often leading to inflammation, are

• phagocytes

• T-cells

• B-cells

• antibodies

Long-term immunity resulting from exposure to a pathogen and thus antibodies production is called

• passive immunity

• herd immunity

• active immunity

• real immunity

Vaccination is a form of

• passive, natural immunity

• active, natural immunity

• passive, smart immunity

• active, artificial immunity

Antigens

• Are chemical markers on pathogens

• Are a type of white blood cell

• Are part of the bodies 3rd line of defense against pathogens

Killer T cells are a type of white blood cell involved in the 3rd line of defense. T cells

• Help to activate other white blood cells such as killer T cells and B cells

• Produce antibodies

• Produce antigens

• Kill specific pathogenic cells