Our defense system

Question 1

What is the 1st line of defence all about?

Answer 1

Stopping the pathogen from getting inside our body.

Question 2

What is the 1st line of defence?

Answer 2

The boarder patrol.

Question 3

What is the outside layers of skin?

Answer 3

The outside layer of skin is layers of dead dry skin.

Question 4

Why is the layers of dead dry skin such a good defence mechanism?

Answer 4

Because it is virtually impenetrable by microbes.

Question 5

What does skin have that stop invading bacteria from multiplying (competition)?

Answer 5

A population of harmless bacteria that stop invading bacteria from multiplying.

Question 6

What are sebaceous glands?

Answer 6

Oil glands.

Question 7

What do sebaceous glands secrete?

Answer 7

Sebum (oil).

Question 8

What are the lipids in sebum broken down by?

Answer 8

By the skins bacteria into acids which inhibit bacterial and fungal growth.

Question 9

What happens if the skin is broken?

Answer 9

Blood clotting mechanisms quickly form a seal.

Question 10

What do mucous membranes secrete?

Answer 10

Mucous. Mucous traps pathogens.

Question 11

What are lined with mucous within our human body?

Answer 11

The digestive, respiratory, reproductive and urinary tracts .

Question 12

What are cilia?

Answer 12

Cilia are Minute hairs that line the nose and some respiratory tubes.

Question 13

What do the cilia hairs do?

Answer 13

The hairs sway in a rhythmic way to move mucous (and trapped pathogens) along for disposal - to nose or throat (coughed or swallowed).

Question 14

What do chemical barriers do?

Answer 14

Create conditions which make the surfaces inhospitable for the potential pathogens.

Question 15

What is an example of a chemical barrier that creates conditions which make the surface inhospitable for the potential pathogen?

Answer 15

The acidic environment in the stomach/the alkaline conditions in the small intestine.

Question 16

What are Microflora?

Answer 16

Harmless micro-organisms that live on the inside or the outside of the body and create acidic conditions that pathogens can’t tolerate or keep the populations of pathogens in check by acting as competitors.

Question 17

What is the second line of defence?

Answer 17

The second line of defence is a group of cells, tissues and organs that work together to protect the body. This is the immune system.

Question 18

What are the cells involved in the second line of defence?

Answer 18

The cells involved are white blood cells (leukocytes), which seek out and destroy disease-causing organisms or substances.

Question 19

What do “Neutrophylls” do in the second line of defence?

Answer 19

These cells primarily attack bacteria. They are dispensable, rather like pawns on a chessboard. They rush to the site of incoming bacteria to fight them, but are easily killed. Neutrophils only last a few days in the body (before they self-destruct), but our bone marrow produces more every day. Some bacteria avoid neutrophils by hiding inside cells.

Question 20

In the second line of defence, what are T-Helper cells?

Answer 20

These cells are like the bosses. They give instructions to other cells by producing signals. Each T helper cell only looks out for one type of pathogen. Many T helper cells are needed to watch for many different diseases or invaders.

Question 21

In the second line of defence, what are Cytotoxic (killer) T cells?

Answer 21

These are killer cells. They punch holes in the walls of the pathogen cell so that the contents ooze out.

Question 22

In the second line of defence, what are macrophages?

Answer 22

Macrophage means ‘big eater’. These cells ‘eat’ (ingest) or clean up the mess of dead cells.

Question 23

In the second line of defence, what are Dendritic cells?

Answer 23

These cells are like the spies. They notice if there is an invader and then present evidence of the invader to T cells in the lymph nodes.

Question 24

In the second line of defence, what are B cells?

Answer 24

These produce antibodies, which lock onto the antigen of invading bacteria and immobilise them until the macrophage consumes them. Some B cells become memory cells after being activated by the presence of antigen. These cells are able to live for a long time and can respond quickly following a second exposure to the same antigen.

Question 25

In the second line of defence, what are Suppressor T cells?

Answer 25

When the infection is gone, the immune system needs to be calmed down (or the killer cells may keep killing). The suppressor T cells slow down or turn off the immune system to prevent damage to good cells.