Human defence systems 4.3.1.6

Question 1

What are the different defence system and what do they do?

Answer 1

• Saliva
• Tears/sweat
• blood clotting
• Hair and mucus
• Skin
• Ciliated cells in the trachea
• Stomach acid
• Good

Question 2

How is our skin a defence system?

Answer 2

• A massive protective barrier covering your entire body

- Produces an antimicrobial substance called sebum that inhibits the growth of pathogens

Question 3

How is our nose a defence system?

Answer 3

Full of hairs and mucus which trap microbes. You blow it out or sniff it to the back of your throat and swallow it.

Question 4

How is our cilia a defence system?

Answer 4

• Mucus traps microbes and ciliated epithelial cells waft it to the back of your throat.
• There you swallow it.

Question 5

How is does eating serve as a defence system?

Answer 5

• Microbes ingested in food enter the stomach which contains hydrochloric acid (pH2)
• Kills most microbes

Question 6

How is our blood a defence system?

Answer 6

If you get a cut, platelets form a scab to stop pathogens from entering and blood loss

Question 7

How is our blood a defence system?

Answer 7

How is our blood a defence system?

Question 8

How is our eyes a defence system?

Answer 8

• This is protected by tears and rapid eye movement (REM)
• REM pushes microbes to the front of your eye
• Tears contains water and salts. Microbes usually die in salty conditions.

Question 9

How is our ears a defence system?

Answer 9

Yellow sticky ear wax. Works in a similar way to nose mucus ( traps pathogens)

Question 10

What is a pathogen?

Answer 10

microorganisms that cause infectious disease

Question 11

How can you reduce the spread of pathogens?

Answer 11

• washing hands
• clean drinking water
• condom
• isolation
• vaccination

Question 12

What 3 ways are pathogens spread and example?

Answer 12

• Air (influenza)
• Water(cholera)
• Direct contact between individuals (HIV)

Question 13

What do invading pathogens do the the cells?

Answer 13

Invading pathogens produce toxins and cause the symptoms by cell damage

Question 14

What are the 3 main white blood cells do?

Answer 14

• Phagocytosis – engulfing pathogens
• Produce antibodies
• Produce antitoxins

Question 15

Describe the process of phagocytosis.

Answer 15

1. Phagocyte recognises invading bacterium as a pathogen
2. The cell membrane of the phagocyte fuses around the bacterium, trapping it. (ENGULFS IT!)
3. Digestive enzymes breaks down the bacteria
4. The cell keeps useful parts and expels the rest.

Question 16

What does the anti-toxin do?

Answer 16

-bind to toxins to prevent harm to human cells