diseases and immunity

Question 1

what is a pathogen?

Answer 1

a disease causing organism

Question 2

what is a transmissible disease?

Answer 2

a disease in which the pathogen can be passed from one host to another

Question 3

what is a vector?

Answer 3

an organism that carries a pathogen from one host to another

Question 4

what is the immune system?

Answer 4

the body’s internal defence system

Question 5

what are phagocytes?

Answer 5

white blood cells that surround, engulf and digest pathogens

Question 6

what are lymphocytes?

Answer 6

white blood cells that secrete (produce and release) antibodies

Question 7

what are antigens?

Answer 7

chemicals on the surfaces of pathogens which are recognised as foreign by the body

Question 8

what are the 4 types of pathogens?

Answer 8

• viruses
• proctoctists
• fungi
• bacteria

Question 9

how is a disease transmitted?

Answer 9

• direct contact
• indirect contact

Question 10

what is direct contact?

Answer 10

transmission through blood and other body fluids

Question 11

what is indirect contact?

Answer 11

transmission from contaminated
surfaces, food, animals and air

Question 12

what are the lines of defence in the body against immunity?

Answer 12

• mechanical barriers
• chemical barriers
• cells

Question 13

what are examples of mechanical barriers?

Answer 13

• collagen in the SKIN to prevent pathogens from entering the body
• hairs in the NOSE to filter out bacteria and foreign particles

Question 14

what are examples of chemical barriers?

Answer 14

• hcl in the STOMACH that kills ingested pathogens
• mucus in the nose, trachea and bronchi that traps pathogens
• ## tears in the EYES which contain the enzyme lyzozyme which dissolves the walls of bacteria

Question 15

what are examples of cell barriers?

Answer 15

• lymphocytes: production of antibodies
• phagocytes: engulfing pathogens - phagocytosis
  **vaccination

Question 16

what measures can be used to control the spread of diseases?

Answer 16

• clean water supply
• hygienic food preparation
• good personal hygiene
• waste disposal
• sewage treatment

Question 17

what is active immunity?

Answer 17

defence against a pathogen by antibody production in the body

Question 18

describe the process of active immunity?

Answer 18

antibodies that are produced by lymphocytes BIND TO antigens that line the surfaces of the pathogens.
(this either destroys them directly or marks them for phagocytes to locate and ingest them)

Question 19

some lymphocytes that produce specific antibodies become ______ _____.

Answer 19

memory cells

Question 20

what is passive immunity?

Answer 20

it is the short-term defence against a pathogen by antibodies acquired by other individuals

Question 21

give an example of passive immunity

Answer 21

• newborn babies receiving antibodies through the placenta + breast milk

(protecting them from contracting diseases while their own immune system develops.)

Question 22

how can active immunity be gained through vaccination?

Answer 22

weakened pathogens are put into the body, which stimulates an immune response by lymphocytes that produces antibodies.
memory cells are produced, giving long term immunity

Question 23

what is the scientific name for cholera?

Answer 23

vibrio cholerae (bacterium)

**WATER BORNE DISEASE

Question 24

how is cholera transmitted?

Answer 24

cholera secretes toxins that irritate intestinal lining. chloride ions are secreted into the small intestines, which triggers water to move into the gut by OSMOSIS - causing diarrhoea + dehydration.

Question 25

what does cholera treatment involve?

Answer 25

treatment includes intravenous rehydration, replacement of salts and use of antibiotics to kill bacteria