B3 Fighting Disease (page 46)

Question 1

The human body has a pretty sophisticated defence system, explain what this is?

Answer 1

the human body has got features that stop a lot of nasties getting inside in the first place.

Question 2

What protection does the skin have on a human?

Answer 2

the skin acts as a barrier to pathogens. It also secretes antimicrobial substances which kill pathogens.

(antimicrobial substances used by the skin are the early stages of immune defense, so it can kill off any nasties before it enters the body).

Question 3

How can your nose trap particles that could contain pathogens?

Answer 3

the Hairs and Mucus in your nose trap particles.

Question 4

How can the Trachea and Bronchi (breathing pipework (see page 30) be used to fight off pathogens?

Answer 4

The Trachea and Bronchi secrete mucas to trap pathogens.

The trachea and Bronchi are lined with cilia. These are hair-like structures, which waft the mucus up to the throat where it can be swallowed.

(cilia moves microbes and debris up and out of the airways).

Question 5

How can the stomach kill off pathogens?

Answer 5

the stomach produces hydrochloric acid. This kills pathogens that make it that far from the mouth.

Question 6

What can your immune system do?

Answer 6

attack pathogens.

If pathogens do make it into your body, your immune system kicks in to destroy them.

Question 7

What is the most important part of your immune system?

Answer 7

white blood cells

Question 8

What do white blood cells do?

Answer 8

They travel around in your blood and crawl into every part of you, constantly patrolling for microbes. When they come across an invading microbe they have three lines of attack.

1. Consuming them
2. Producing Antibodies
3. Producing Antitoxins

Question 9

Every invading pathogen has unique molecules on its surface, what are they called?

Answer 9

antigens

Question 10

What happens when some types of white blood cell comes across a foreign antigen (one they don’t recognise)?

Answer 10

they will start to produce proteins called antibodies to look onto the invading cells so that they can be found and destroyed by other white blood cells.

(the antibodies produced are specific to that type of antigen - they won’t lock on to any others)

Question 11

When Antibodies are produced what do they then do?

Answer 11

they are produced rapidly and carried around the body to find all similar bacteria or virses.

Question 12

If the person is infected with the same pathogen again, what will happen with the white blood cells?

Answer 12

again, the white blood cells will rapidly produce the antibodies to kill it - the person is naturally immune to that pathogen and won’t get ill.

(look at diagram on page 46)

Question 13

The white blood cells that produce antibodies are also known as what?

Answer 13

B-lymphocytes

Question 14

Why do white blood cells produce Antitoxins?

Answer 14

these counteract toxins produced by the invading bacteria.

Question 15

If you have a low level of white blood cells, what do this mean?

Answer 15

you’ll be more suscepible to infections.

Question 16

When HIV attack white blood cells what happens?

Answer 16

this weakens the immune system, making it easier for other pathogens to invade.

Question 17

White blood cells can engulf foreign cells and digest them. what is this called?

Answer 17

Phagocytosis.

Question 18

What is Phagocytosis? (1 mark)

Answer 18

It is when white blood cells engulf foreign cells and digest them (1 mark)

Question 19

How are the trachea and the bronchi adapted to defend against the entry of pathogens? (3 marks)

Answer 19

They secrete mucus to trap pathogens (1 mark). They have cilia (1 mark), which waft the mucus up to the back of the throat where it can be swallowed (1 mark)