Disease and the Immune system Flashcards
define the term disease
a condition that impairs the normal functioning of an organism
what is a pathogen
an organism that causes disease
what is a communicable disease
a disease that can be spread between organisms
what type of pathogen causes TB and what does it commonly affect
bacterium, animals typically humans and cattle
what type of pathogen causes bacterial meningitis and what does it commonly affect
bacteria and humans
what type of pathogen causes ring rot and what does it commonly affect
bacteria, potatoes and tomatoes
what type of pathogen causes HIV and what does it commonly affect
virus and humans
what type of pathogen causes tobacco mosaic virus and what does it commonly affect
virus, plants
what type of pathogen causes influenza and what does it commonly affect
animals, including humans
what type of pathogen causes ringworm and what does it commonly affect
fungus and cattle
what type of pathogen causes athletes foot and what does it commonly affect
fungus and humans
what type of pathogen causes potato/tomato late blight and what does it commonly affect
protoctist and potatoes/tomatoes
what type of pathogen causes malaria and what does it commonly affect
protoctist and animals including humans
what type of pathogen causes black Sigatoka and what does it commonly affect
fungus and banana plants
what is direct transmission and what type of diseases can be transmitted this way
when a disease is transmitted directly from one organism to another through droplet infection, intercourse or touch
HIV and athletes foot
what is indirect transmission and what examples of disease can be transmitted this way
when a disease is transmitted via a medium
malaria
what factors affect transmission
living conditions, social factors, climate
what are some non specific defence mechanisms against pathogens
skin- physical and produces chemicals which are antimicrobial
mucous membrane- traps pathogens
inflammation- swelling helps isolate pathogens that have entered damaged tissue and vasodilation increases blood flow to affected area
wound repair- skin repair using collagen fibres
expulsive reflexes- sneezing
what are some examples of plant physical defences
waxy cuticle acts as a physical barrier
cell walls
callose deposited between plant cell walls and plasma membranes which can make it harder for pathogen to enter the cell
what are antigens
molecules found on the surface of cells
describe the process of phagocytosis
phagocyte recognises antigens on a pathogen
cytoplasm of phagocyte moves around pathogen, engulfing it
this is made easier by opsonins that are in blood and attach to foreign antigens to aid phagocytes
pathogen is contained in a phagosome
a lysosome fuses with the phagosome
the phagocyte then presents the pathogen’s antigens and is known as an antigen-presenting cell
what type of white blood cell are a type of phagocyte
neutrophils
what proteins act as messenger molecules send signals to neutrophils
cytokines
What is a T lymphocyte
a type of white blood cell covered in receptors
how do t lymphocytes work
the receptors on the surface bind to a complimentary antigen and this activates the t lymphocyte known as clonal selection, the t lymphocyte then undergoes clonal expansion and it divides to produce clones of itself
what are the different types of t lymphocytes and what are their functions
T helper cells- release substances to activate B lymphocytes and T killer cells
T killer cells- attach and kill cells that are infected with a virus
T regulatory cells- suppress the immune response from other white blood cells, to stop immune system cells from mistakenly attacking the hosts body cells
some activated T cells become memory cells
describe the process of B lymphocyte activation and plasma cell production
B lymphocytes are covered in antibodies
each b lymphocyte had a different shaped antibody so bind to different shaped antigens to form antigen-antibody complex
this, together with substances released from T helper cells activates the b lymphocyte
this is another example of clonal selection
activated b lymphocyte then divides by mitosis in plasma cells and memory cells
another example of clonal expansion
how is cell signalling used in the immune response
T helper cells release interleukins that bind to receptors on B lymphocytes
name three types of white blood cells
monocyte, lymphocyte, neutrophil
what is the structure of an antibody
glycoproteins
made up of four polypeptide chains- two heavy chains and two light chains
variable regions form the antigen-binding sites
hinge region allows flexibility when antibody binds to antigen
constant regions allow binding to receptors on immune system cells
disulphide bridges hold chains together
what are the three main ways antibodies help clear infection and give a brief description of each
agglutinating pathogens- antibody binds to two pathogens and they become clumped together, then undergoes phagocytosis
neutralising toxins- anti-toxins can bind to the toxins produced by pathogens so they don’t affect human cells
preventing the pathogen binding to a human cell- antibodies bind to antigens on pathogens so block cell-surface receptors that pathogens need to bind to host cells
what is the primary immune response
when a pathogen enters the body for the first time and the antigens on the surface activation the immune system
what do both T and B lymphocytes produce
memory cells
what does the term immune mean
immune system has the ability to respond quickly to a second infection
compare primary and secondary response
primary- enters first time, slow, B and T lymphocytes, symptoms
secondary- enters for second time, fast, memory cells, no symptoms
what is active immunity and what are the two types
when immune system makes its own antibodies after being stimulated by an antigen
natural- when you become immune to a disease after catching it
artificial- immune after vaccination
what is passive immunity and what are the two types
type of immunity when you get given antibodies made by a different organisms
natural- when a baby receives antibodies through placenta and breast milk
artificial- getting injected with antibodies from someone else
what are the differences between active and passive immunity
active- requires exposure to antigen, takes a while to develop, protection is long term, memory cells produced
passive- no exposure to antigen, production is immediate, short-term, memory cells not produced
what is an autoimmune disease and give an example
when an immune system cannot recognise self antigens so are treated like foreign antigens, lupus
how does vaccination work
vaccines contain substances that cause your body to produce memory cells without the pathogen causing disease
substances tend to be dead or attenuated pathogen
can also be mRNA designed to code for antigens on a pathogen
what is herd immunity
when a large percentage of a population is vaccinated so even those who haven’t been vaccinated are unlikely to get the disease
define the term vaccination
the administration of a substance designed to stimulate the immune system
what are antibiotics
chemicals that kill or inhibit the growth of bacteria
what causes antibiotic resistant bacteria
genetic variation due to mutations and that allele being passed on to offspring
what are the problems with antibiotic resistant bacteria
increased use of antibiotics increases antibiotic resistant strains developing
how are doctors trying to prevent the development of antibiotic resistant bacteria
developing new antibiotics or modifying existing ones
reduce distribution of antibiotics
take all the antibiotics to make sure infection is fully cleared
