Pathogens
Define 'pathogen'
A biological agent of disease
Droplets
Direct contact
Faeces
Contaminated foods
Animals
Body fluids
State the three things that pathogens must be able to do in hosts to be successful
1. enter 2. survive 3. reproduce
the ‘natural’ or ‘inborn’ immune system - this means it is non specific
Explain what the 'adaptive immune system' is
involves specific antigens and specific pathogen recognition
retains memory of the pathogen in the event of secondary exposure
State the two pathogens that are non-living
Viruses, prions
Define 'vector'
organisms that transmit pathogens and facilitate the spread of infectious diseases.
State the four entry points in which humans are vulnerable to infection
Respiratory surfaces
Wounds
Digestive system
Reproductive organs
State two processes that the innate system involves
Phagocytes and phagocytosis (a type of endocytosis)
Non-self recognition of particular molecular patterns found in pathogens
Cells such as white blood cells and killer cells
Chemicals e.g. complement, histamine
The inflammatory response
List two secondary organs of the adaptive immune system
1. lymph nodes 2. spleen 3. tonsils
State all 6 pathogens
Virus, prion, protist, bacteria, parasite, fungi
State an example of a disease spread through direct contact
genital herpes etc
State and explain two physical barriers to disease (first line of defence)
any acceptable answers
The complement system consists of proteins that are secreted by cells around the body. They are inactive until they bind to surface receptors of the surface of pathogens.
State the three processes of the complement system.
Bind to and puncture holes in cell membranes.
Bind to surface molecules on pathogens and increase the chances of the pathogen being taken up and destroyed by phagocytes.
Bind to what are called mast cells stimulating them to release a chemical called histamine.
Explain what the Major histo-compatability complex MHC is
A set of protein markers found on the surface of cells that can either be self or non-self.
the non-self proteins are sections of protein antigens from pathogens (the ‘flags’ the cell displays to alert of the infection).
State two infectious diseases, AND two non-infectious diseases
any acceptable answer
eg: influenza, malaria / cancer, asthma etc
Explain the difference between a pandemic and an epidemic
epidemic - outbreak within a nation or region
pandemic - outbreak in multiple countries/ continents/ global
State and explain two pathogen adaptations
Use a vector
Attach to host tissues
Have the ability to withstand harsh environments (such as stomach acid neutralisation)
Biofilms
Produce toxins
Bind to molecules on the surface of host cells
Ability to survive in white blood cells
Ability to alter host behaviour - making them sneeze when they’re sick
Change antigens on the surface of the microbe
Superbugs - resistance to antibiotics
Avoid white blood cells
Viral replication
State four characteristics of the inflammatory response
Swelling
Redness
Pain
Heat
Explain how B-cells produce antibodies.
1. they're activated when their unique B-cell receptor (BCR) recognises a specific antigen (complementary binding)
2. activated B-cell then divides -clonal expansion- to produce cells that differentiate into antibody-secreting plasma cells and memory B-cells.
3. Plasma cells then release the specific antibodies into the bloodstream and other bodily fluids to neutralise pathogens and infected cells.
State the pathogen responsible for BVE (Mad Cow's Disease) and explain one social, ethical, or economic consequence of the disease.
- any acceptable answer eg beef imports banned, millions of cows were killed, etc
Explain the difference between biological vectors and mechanical vectors
Biological vectors - mosquitoes and ticks for diseases like malaria and Lyme disease.
Mechanical vectors - flies and rodents, transfer pathogens without participating in their life cycle.
State and explain one barrier in the first line of defence that also acts as a mode of transmission of disease.
Sneezing or coughing, and an explanation as to why
Explain how Natural Killer Cells (NKCs) work to fight infections
Recognising protein markers as ‘non-self’ on cells that need to be destroyed
Releasing cytokines which are cell-signalling molecules that guide other responses
Attacking in numbers and punching holes through the cells they need to destroy
Explain the difference between Active, Passive, and Herd immunity.
Active:
Exposure to the actual pathogen
Exposure to a vaccination
Passive immunity:
Passing on ready made antibodies
Vital in unborn/newborns - eg placenta and breastmilk
Herd immunity:
Understanding that there is a decrease in pathogen spread when others around you are vaccinated.
(resistance to the spread of an infectious disease within a population that is based on pre-existing immunity of a high proportion of individuals as a result of previous infection or vaccination).