Lesson 4 Barriers

Question 1

What are chemical barriers?

Answer 1

Some type of secreted chemical that helps prevent the entry of a pathogen

Question 2

What are physical barriers?

Answer 2

Physical barriers are physical structures that prevent the pathogen from entering
(Fly screen prevents flies from the house)

Question 3

What does intact skin do?

Answer 3

Physical barrier - Blocks the entry
Chemical Barrier - Both fatty and salt acids are secreted in sweat onto the skin which then become bacterial inhibitors that prevent pathogen infection

Question 4

How does hair protect pathogens from entering?

Answer 4

Hair in both ear and nose trap foreign particles and some invading pathogens.

Question 5

Ear wax

Answer 5

Ear wax coats the inner lining of the ear preventing entry of pathogens and trapping foreign particles

Question 6

How do tears and saliva act as a chemical barrier?

Answer 6

Lysozymes are secreted in your saliva. Tears also contain lysozyme
Lysozymes are enzymes that break bacterial cell walls, so bacterial cells burst due to osmosis.

Question 7

How does Mucus prevent the entry of a pathogen?

Answer 7

Acts as a chemical barrier that secretes by goblet cells and traps invading pathogens

Question 8

Cilia

Answer 8

The nose and lungs contain cilia. These are small hair-like projections that allow for the removal of foreign substances that get trapped in mucus, by moving them out of the lungs

Question 9

Stomach and Digestive system

Answer 9

Secretes HCL (strongest acid pH2)
The acid kills the majority of pathogens that enter the digestive system.

Question 10

Microbial Barriers

Answer 10

Many microbes live in a symbiotic relationship with humans called mutualism where both organisms benefit from this relationship. The microbes outcompete pathogenic bacteria for space and nutrients preventing them from establishing colonies in the human body.