Understanding the Immune System Functions

What is a pathogen?

• A type of beneficial bacteria

• A substance that helps the immune system

• A disease-causing agent

• A type of white blood cell

Which of the following is considered a first line of defense against pathogens?

• Macrophages

• Skin

• T cells

• Histamine

What is one effect of histamine release during an inflammatory response?

• It causes blood vessels to narrow

• It makes blood vessels leakier

• It directly destroys pathogens

• It produces antibodies

How do cytotoxic T cells destroy infected cells?

• By engulfing them whole

• By releasing antibodies

• By causing the infected cell to self-destruct

• By widening blood vessels

What causes cytotoxic T-cells to become active and destroy infected cells?

• Direct contact with free-floating pathogens

• Signals from B-cells

• Antigens displayed on the surface of infected cells

• Chemicals released by other healthy cells

What is the main role of Helper T-cells in the immune system?

• To directly attack and kill pathogens

• To produce antibodies that fight infection

• To activate other types of white blood cells

• To consume and digest foreign invaders

What are antibodies?

• Foreign substances that trigger an immune response

• Medicines used to kill bacteria

• Proteins produced by the immune system that target specific foreign substances

• Cells that engulf and destroy pathogens

How do vaccines help protect a person from getting sick in the future?

• They introduce strong, active pathogens into the body to cause a mild illness.

• They directly kill all harmful pathogens present in the body.

• They train the immune system to create memory cells that recognize specific pathogens.

• They provide the body with antibiotics to prevent bacterial infections.