Physical and Chemical External Defenses - Non specific defences

Question 1

What are 4 external (physical barriers) defences

Answer 1

1. Skin
2. Mucus
3. Hair
4. Cilia

Question 2

What are 2 external (chemical barriers) defences

Answer 2

1. Acids
2. Lysosomes

Question 3

How does the skin protect the body against pathogens?

Answer 3

Bacteria live on the skin causing other pathogens to not be established. Sebreum is an oily secretion that kills some pathogenic bacteria. Sweat contains salts and fatty acids that prevent bacteria growth.

Question 4

How does mucus protect the body against pathogens?

Answer 4

Goblet cells produce mucus which traps particles. The mucus membranes line body cavities that open to the exterior. They line the digestive, urinary and reproductive tracts.

Question 5

How does hair protect the body against disease?

Answer 5

Hair is found in the nasal cavity and traps particles.

Question 6

How does cilia protect the body against disease?

Answer 6

Cilia are tiny hair-like projections that beat. Beating is the cilia moving back and fourth. They are found in the nasal cavity and trachea. They move trapped particles in the mucus towards the throat to be coughed up.

Question 7

How do acids protect the body against disease?

Answer 7

The acid will break down and kill pathogens. The stomach contains gastric acids, the vagina has bacteria that secrete lactic acid and hydrogen peroxide and sweat and urine are slightly acidic.

Question 8

How do lysozymes protect the body against pathogens?

Answer 8

Lysozyme is an enzyme that kills bacteria. It is found in tears, saliva, sweat, nose secretions, tissue fluid and cerumen (ear wax)