Defence against disease - Human Defence

Question 1

what is the definition of non specific defence systems?

Answer 1

generalised defence against any pathogen

Question 2

definition for specific defence system

Answer 2

defence against a specific type of pathogen due to its unique antigens

Question 3

what are the non-specific defence systems of the human body:

Answer 3

• skin
• nose
• trachea and bronchi
• stomach
• tears

Question 4

what is the role of skin in the 1st line of defence:

Answer 4

• skin covers the whole body and provides a physical barrier that is difficult for microbes to penetrate
• Sebaceous glands in skin produce oils which help kill microbes

Question 5

what is the role of stomach in the 1st line of defence:

Answer 5

• produces hydrochloric acid which kill microbes that are swallowed

Question 6

what is the role of the nose in the 1st line of defence:

Answer 6

• Nasal hairs at as a physical barrier against dust + latger micro-organisms
• sticky mucus traps dust and microbes, expelled by sneezing, blowing nose or swallowed + destroyed by stomach acid

Question 7

which cells secretes mucus

Answer 7

goblet cells

Question 8

what is the role of the trachea and bronchi in the 1st line of defence:

Answer 8

• goblet cells produce further mucus which traps microbes
• Ciliated cells contain cilia (protrusions) which beat rhythmically to propel mucus back up the airway to the back of the throat
• a cough moves this down the oesophagus into the **stomach

Question 9

what is the role of tear in the 1st line of defence:

Answer 9

• contain enzymes = lysozymes which destroy microbes, preventing them from entering the eyes

Question 10

what the is next line of denfence

Answer 10

immune system

Question 11

where can white blood cells be found

Answer 11

• circulating around the body in the plasma travelling through the blood vessels
• static in some organs e.g. liver, brain

Question 12

what are the 3 types of white blood cells

Answer 12

• phagocytes
• B-Lymphocyte
• T-Lymphocyte

Question 13

what are phagocytes and how do they defend the body

Answer 13

• non-specific white blood cells
• engulf and break down bacteria by phagocytosis

Question 14

how can white blood cells help to defend against pathogens

Answer 14

• phagocytosis
• production of antibodies
• production of antitoxins

Question 15

what type of defence is phagocytosis

Answer 15

non-specific - target anu invading pathogen

Question 16

describe the stages of phagocytosis

Answer 16

1. Antibodies cause pathogens to clump together (agglutination)
2. Phagocyte flows around pathogen to **engulf* them in a vacuole
3. **Enzymes* added to vacuole to break down / digest pathogens cell walls + membranes

Question 17

describe how B-Lymphocytes defend the body from antigens

Answer 17

• recognise proteins on the surface of foreign antigens
• produce antibodies that are specific and have complementary binding sites to the specific shape of a particular antigen

Question 18

what are the role of T-Lymphocytes

Answer 18

• produce antitoxins that counteract / neutralise toxins produced by bacterial cells