1.60. Barriers to Pathogens http://www.ck12.org
1.60 Barriers to Pathogens
- Describe your body’s first line of defense against pathogens.
What is your nose good for?
Your nose does a lot of work for you! Obviously, it helps you breathe and provides your sense of smell. But you
might not realize that your nose also helps to fight off disease.
The Immune System’s First Line of Defense
Your body has many ways to protect you from pathogens. Your body’s defenses are like a castle. The outside of a
castle was protected by a moat and high walls. Inside the castle, soldiers were ready to fight off any enemies that
made it across the moat and over the walls. Like a castle, your body has a series of defenses. Only pathogens that
get through all the defenses can harm you.
Your body’s first line of defense is like a castle’s moat and walls. It keeps most pathogens out of your body. The first
line of defense includes different types of barriers.
Skin and Mucous Membranes
The skin is a very important barrier to pathogens. The skin is the body’s largest organ. In adults, it covers an area of
about 16-22 square feet!
The skin is also the body’s most important defense against disease. It forms a physical barrier between the body and
the outside world. The skin has several layers (Figure1.119). The outer layer is tough and waterproof. It is very
difficult for pathogens to get through this layer of skin.