10. Diseases and Immunity Flashcards
What is a pathogen?
a disease-causing organism
What is a transmissible disease?
a disease in which the pathogen can be passed from one host to another
What are the main ways a pathogen can be transmitted?
direct contact
by air
by animal vector
by food
by blood/other body fluids
How can we categorize the main two ways a pathogen can be transmitted?
direct contact: including through blood and other body fluids
indirectly: including from contaminated surfaces, food, animals and air
State 5 body defences.
- skin
- hairs in the nose
- mucus
- stomach acid
- white blood cells
What are 5 methods to control the spreading of disease?
- clean water supply
- hygienic food preparation
- good personal hygiene
- waste disposal
- sewage treatment
Define ‘active immunity’.
defence against a pathogen by antibody production in the body
What are antigens? Where are they found?
they are substances that can induce the body to produce an immune response
found in pathogens, each has their own antigens
What is the shape of antigens?
the shape varies, but each pathogen has its own antigens
What are antibodies?
proteins produced by lymphocytes that will help destroy (mark for destruction by phagocytes) or directly destroy a pathogen
What are two ways that antibodies function?
- directly destroy pathogens
- mark pathogens so phagocytes can destroy them
What is something a specific antibody must have in order to destroy a specific pathogen?
a complementary shape to fit the specific antigens
Define ‘active immunity’.
person exposed to pathogen
person’s own lymphocytes produce antibodies + memory cells
What are two methods of active immunity?
- infection by pathogen
- vaccination
Outline the process of vaccination.
- weakened pathogens/antigens are put into the body
- antigens stimulate an immune response from lymphocytes
- lymphocytes produce antibodies to destroy pathogen
- memory cells are produced, causing long-term immunity
Explain the role of vaccination in controlling the
spread of diseases.
when everyone is vaccinated and protected from a pathogen, disease spread is much more controlled
Define ‘passive immunity’.
a short-term defence from a pathogen acquiring antibodies from another source
What are two examples of passive immunity?
- across placenta
- breast milk
What is an advantage of passive immunity?
protection occurs immediately
What are two disadvantages of passive immunity?
protection is short-term
memory cells are not produced
Why is breast-feeding important?
passive immunity is developed in infants and help babies be protected until they can take their first vaccines
Describe the antibody response stages after vaccination.
- person is vaccinated
- primary immune response: slow production of antibodies by lymphocytes
- primary production of memory cells
- secondary immune response: person infected again, faster and stronger production of antibodies by memory cells
- secondary production of memory cells: store antigen memory for longer
What is cholera?
a disease caused by a bacterium which is transmitted in contaminated water
What are symptoms of cholera?
diarrhoea
dehydration
vomiting
(loss of ions from blood)
What does the cholera bacterium do?
produces a toxin which secretes chloride ions into small intestine
causes osmotic movement of water into the gut
What is a vector?
an organism that transmits a pathogen from an infected to a non-infected person
What are direct methods of transmission?
exchange of blood and body fluids
What are indirect methods of transmission?
by air
by food/drink
by animal vector
by touching contaminated substances/surfaces/food
What are the two types of barrier in the first line of defence?
mechanical barriers and chemical barriers
What does the first line of defence do?
prevent pathogens getting into the body or damaging its surfaces
What does the second line of defence do?
detects and destroys pathogens, once pathogen gains entry to the body
What do mechanical barriers do?
block pathogens from entering the body
What do chemical barriers do?
substances that trap or kill pathogens
Examples mechanical barriers
- skin
- hairs in the nose
Examples chemical barriers
- mucus
- stomach acid
What are memory cells?
- cell formed from a lymphocyte as the immune system responds to an infection
- remains in bloodstream + can recognise pathogens that infect after a first infection
- then differentiates to form antibody-producing lymphocytes that mount a secondary response
