diseases and immunity

Question 1

pathogen definition

Answer 1

disease-causing organism

Question 2

host definition

Answer 2

organism that is infected by a pathogen

Question 3

Pathogens include:

Answer 3

• Bacteria
• Fungi
• Protoctists

Question 4

transmissible disease

Answer 4

a disease caused by a pathogen that can be transmitted from one host to another
diseases can be transmitted either;
- directly: contact through body fluids such as blood
- indirectly: through air, water, food, contaminated surfaces or animals

Question 5

mechanical barriers

Answer 5

block pathogens from entering the body
include:
- Skin
- Hairs in the nose

Question 6

chemical barriers

Answer 6

• substances that trap or kill pathogens
  include:
  
  • Mucus produces pra mucous membranes. They are sticky, therefore they trap bacteria and other pathogens
    
    • Stomach acid. Highly acidic therefore kills pathogens

Question 7

2 types of white blood cells

Answer 7

phagocytes
lymphocytes

Question 8

what do phagocytes do?

Answer 8

surround and engulf a pathogen (phagocytosis) then destroy it

Question 9

what do lymphocytes do?

Answer 9

produce antibodies, proteins which attach to pathogens and so mark them for destruction

Question 10

controlling the spread of diseases

Answer 10

• A clean water supply
• Good personal hygiene
• Hygienic food preparation
• Proper waste disposal
• Treatment of sewage

Question 11

active immunity

Answer 11

production of antibodies by the immune system in response to antigens - gained after infection of that pathogen

Question 12

passive immunity

Answer 12

temporary immunity - gained when antibodies are transferred to the body from another individual (for example milk during breast-feeding)

Question 13

Once attached to the antigen, the antibody can:

Answer 13

• mark the antigen for phagocytosis and destruction by phagocytes
  or
  
  • cause the pathogen to break open and die

Question 14

primary response

Answer 14

when the immune system responds to a specific pathogen for the first time

Question 15

secondary response

Answer 15

immune system after re-infection of the same pathogen. Involves memory cells

Question 16

memory cells

Answer 16

remain in the blood after the pathogens in an infection have been destroyed. They ‘remember’ specific pathogens, so that if the organism is infected again, the immune system may produce antibodies quicker.

Question 17

what do vaccines contain?

Answer 17

small amounts or dead or weakened pathogens that cannot cause disease