5.2.1 Primary Defenses

• Primary defenses are physical and chemical barriers that prevent pathogens from entering the body
• How does stomach acid act as a primary defense against pathogens?

  Destroys pathogens
• Cilia move mucus and trapped pathogens out of the body.

  True
• Cilia are found on the surface of mucous membranes and move mucus and trapped pathogens out of the body.


  True
• Stomach acid destroys pathogens that enter the body through food and drink.


  True
• What is the role of skin as a primary defense against pathogens?

  Waterproof barrier
• The skin provides a tough, waterproof layer that pathogens cannot easily penetrate
• What type of tracts do mucous membranes line in the human body?

  Respiratory and digestive
• What is the primary role of primary defenses in the immune system?

  Prevent pathogen entry
• What are the two types of barriers that make up primary defenses in the immune system?

  Physical and chemical
• Cilia move mucus and trapped pathogens out of the body by beating in a coordinated manner
• Steps in the destruction of pathogens by stomach acid

  1️⃣ Maintains a low pH

  2️⃣ Denatures pathogen proteins

  3️⃣ Disrupts cell walls
• What are the two types of roles the skin plays in preventing pathogen entry?

  Physical and chemical
• What process does stomach acid use to destroy pathogens by breaking down their proteins?

  Denaturation
• What are primary defenses in the immune system designed to do?

  Prevent pathogen entry
• Mucous membranes trap pathogens in sticky mucus.

  True
• What do mucous membranes secrete to trap pathogens?

  Mucus
• Mucous membranes trap pathogens in sticky mucus
• The skin is a tough, waterproof barrier that pathogens cannot easily penetrate
• Match the physical barrier with its description:

  Skin ↔️ Tough, waterproof layer

  Mucous Membranes ↔️ Traps pathogens in mucus

  Stomach Acid ↔️ Destroys pathogens in food
• Stomach acid maintains a pH between 1.5 and 3.5, creating a hostile environment for pathogens.


  True