Immune System Flashcards
Disease
any conidition in which the body or parts of the body do not function properly
Infectious disease
diseases that are caused by pathogens
Main ways disease is spread
direct contact with an infected person, animal or their discharges
Contaminated food and water
Disease-carrying insects
pathogen
harmful disease causing organism
Bacteria infections are treated with
antibiotics
contagious infection
Spread by physical contact
How is death measured
CFR (case fatality ratio) the percentage of infected people that die from it
How is contagiouness measured
the average number of people that an infected person passes the disease to, assuming R0
what is R0
assumption that no-one is protected by vaccination or previous exposure to the disease
Immune system
Special organs, cells and chemicals that fight infection (microbes)
Main parts of immune system
white blood cells
antibodies
complement system (proteins that assist defence e.g. burst open infected cells)
lymphatic system
spleen
bone marrow
thymus
How many lines of defence
3
1st line of defence
physucal barriers to prevent infection
Skin
It forms a physical barrier between the body and the outside environment
Outer layer of skin
he epidermis, consists of dead cells filled with the protein keratin. These cells form a tough, waterproof covering on the body, difficult to get in.
Inside of mouth and nose are lined with
mucous membranes
Other organs that are exposed to substances from the environment are
lined with mucous membranes
mucous membranes produce
mucous
Mucus is
sticky, moist secretion that covers mucous membranes. The mucus traps pathogens and particles so they can’t enter the body.
any mucous membranes are also covered with
cilia
Cilia
tiny, hair-like projections that move in waves and sweep mucus and trapped pathogens toward body openings
Biological 1st line
millions of bacteria that compete with harmful bacteria for food and space. They prevent the harmful bacteria from multiplying
Chemical barriers 1st line
Variety of fluids, including tears, saliva, and sweat.
fluids contain enzymes called
lysozymes which break down the cell walls of bacteria and kill them
hydrochloric acid (stomach acid)
This acid kills most pathogens that enter the stomach in food or water
Urine
also acidic, so few pathogens are able to grow in it.
Air entering though nose
is filtered by hairs
Vomiting
Quick way of getting rid of something in the stomach
Diarrhoea
Quick of way of getting rid of something that has gone past the stomach
When pathogen enters tissues
the affected area becomes red hot and swollen
Histamine
hormone that increases blood flow to cells
When bacteria enter body
damaged nearby cells trigger immune system to start
First cells to show up
macrophages
macrophages
very large cells that digest bacteria
second cells to show up
neutrophils
neutrophils
smaller cells that kill cells by vomiting harmful substances or digesting including your own,
neutrophils self destruct
they self destruct to prevent them from hurting more than they need to, they release a net of chemicals to kill bacteria even after they die, they kill even after theyre ‘dead’
colateral proteins
bacteria inside inflamed fluid that rips apart pathogens
second line of defence
general responses to infection
dendritic cells
ripping apart sampled bacteria, goes around the bloodstream finding the T Cell by rubbing bacteria on it to help recognise it
Your immune system has a type of T cell
for every disease in the universe
when dendritic cell finds t cell
activates third line of defence by multiplying itself and splitting into two groups
t cells at infection site
uses chemical signals to renegrise macrophages and instruct them to destroy the bacteria
what is pus
the collection of dead white blood cells
fever function
Making the body less favourable for replicating viruses and bacteria
Assists movement of white blood cells
Drives activity of certain immune proteins
pyrogens
induce fever by triggering the hypothalamus which triggers the endocrine and nervous systems
Once the pyrogens are no longer being released
body temperature will return to normal.
third line of defence
identify and destroy specific pathogens
build long-lasting immunity against the pathogens in case they infect the body again
The third line of defence is made up of
specialized white blood cells.
strength of the third line of defence is that
it can develop an effective weapon and builds immunity
t cells not at infection site
finding B cells, when it does b cells multiply and produce lots of antibodies
B cells
are antibody factories and can produce the right antibody for every disease in the universe
antibodies
protein superweapons that grab, stun (by surrounding to stop them from moving), lets white blood cells destroy easier
after bacteria is mostly gone
second and third line begin to self destruct to conserve energy
remaining T and B cells
turn into memory cells, produce small amounts of antibodies
antibodies help recognise
which cells are the pathogens
Vaccinations
a type of medicine that trains the body’s immune system to simulate a pathogen to build memory against it without exposing humans to the full strength of disease
Types of vaccines
live attenuated (live but weakened), inactive (dead) that still trigger response, subunit vaccines (made of only the part that triggers the response), DNA vaccines (mad of only the dna that triggers the response),
downside
live attenuated pose a risk for lower immune systems, inactive doesn’t build long lasting immunity,
A vaccine triggers
third line of defence, B cells to produce antibodies and memory cells that remain in the body.
Vacccines allow the immune system to quickly identify
and fight the pathogen in any future infection by building immunity
