First Lines of Defence - Physical and Chemical Barriers

Question 1

Examples of Physical Barriers of the First Line of Defence:

Answer 1

• Skin
• Ears
• Eyes

Question 2

Examples of Chemical Barriers of the First Line of Defence:

Answer 2

• Mucous Membranes
• Stomach Acid (Gastric Juice)

Question 3

Description of Skin:

Answer 3

It provides the major barrier to pathogens. Outer part is called Epidermis. Triple Part is called Thomas.

Question 4

Description of Ears:

Answer 4

There are hairs in the External Ear. Earwax (cerumen) is a mixture of secretions rich in fatty acids which is responsible for low pH (3-5). This low pH inhibits the growth of many pathogenic microbes.

Question 5

Description of Eyes:

Answer 5

Tears contain lysozyme. The eye has Lacrimal glands, a Lacrimal canal and Nasolacrimal ducts.

Question 6

Description of Mucous Membranes:

Answer 6

A membrane that lines various cavities in the body and surrounds internal organs. The surface cells are continuously shed and are replaced by stem cells. This shedding process removes the attached microbes.

Question 7

Description of Stomach Acid (Gastric Juice):

Answer 7

Gastric Juice: HCI, enzymes (pepsin) and mucus.
PH: 1.2-3.0 - Very high acidity. Capable of destroying bacteria and most bacterial toxins.

Question 8

What do the Physical Barriers do?

Answer 8

• Obstruction against pathogens

Question 9

What do the Chemical Barriers do?

Answer 9

• Killing or attacking pathogens