immunity and diseases Flashcards
what is a pathogen
disease-causing organism
what is a transmissible disease
Pathogens are passed on from one host to another
what are the 2 ways pathogens can be passed from host to host
direct contact
indirect contact
what is direct contact
the pathogen is passed directly from one host to another by transfer of body fluids
(blood, semen, phlegm etc.)
what is indirect contact
the pathogen leaves the host and is carried in some way to another, no man to man contact
what are the 3 defences against pathogens
1) mechanical barriers
2) chemical barriers
3) cells
what are the mechanical barriers
structures that make it difficult for pathogens to get past them and into the body
Skin (covers almost all parts of your body to prevent infection from pathogens)
hairs in the nose (these make it difficult for pathogens to get past them further up the nose so they are not inhaled into the lungs)
what are the chemical barriers
substances produced by the body cells that trap / kill pathogens before they can get further into the body and cause disease
Mucus (made in various places in the body, pathogens get trapped in the mucus and can then be removed from the body)
HCL in stomach (strong enough to kill any pathogens that have been caught in mucus in the airways and then swallowed or have been consumed in food or water)
what are the cell barriers
different types of white blood cell work to prevent pathogens reaching areas of the body they can replicate in
phagocytosis - engulfing and digesting pathogenic cells
production of antibodies
how do antibodies work
clump pathogenic cells together so they can’t move as easily (known as agglutination) and release chemicals that signal to other cells that they must be destroyed
what creates antibodies
B-lymphocytes
what is active immunity
Making antibodies and developing memory cells for future response to infection is known as active immunity
what are 2 ways active immunity can be formed
- The body has become infected with a pathogen and so the lymphocytes go through the process of making antibodies specific to that pathogen
- Vaccination
features of active immunity
slow acting and provides long-lasting immunity
what is passive immunity
ready-made antibodies, from another source, are introduced to the body
features of passive immunity
fast-acting, short-term defence
passive immunity doesn’t form its own antibodies or memory cells
what are 2 ways passive immunity can be formed
From mother to infant via breast milk
injected antibodies
what part of the pathogen is recognised by the immune system
antigen
explain how vaccination can control the spread of diseases
harmless pathogen used in the vaccine which is injected
lymphocytes make antibodies
antibodies attack the pathogens, causes pathogens to stick together, restricting the movement and then phagocytes engulf them
antibodies form memory cells that remember the same pathogen for faster antibody production in future infections.
this forms active immunity which creates a rapid and effective immunity against the same pathogen
describe active transport
using energy from respiration, molecules move from an area of lower concentration to higher concentration, up the concentration gradient, into the cell
