The Human Defence System Flashcards
pathogen
an organism that causes disease
immunity
is the ability to resist infection
general defence system definition
acts as a barrier to all pathogens attempting to gain entry to the human body
1st line of general defence system
skin - barrier
lysozyme - enzyme found in sweat etc - bursts wall of bacteria
clotting - helps prevent pathogens getting in
mucous and cilia - in respiratory system traps pathogens
acid - in stomach and vagina kills bacteria
Skin
barrier to infection
prevents pathogens entering
lysozyme
enzyme found in sweat, tears, saliva,
Attacks and dissolved the cell walls of many bacteria (bursts walls of bacteria)
clotting
prevents entry of further pathogens
mucous and cilia
in respiratory system trap pathogens and prevented from entering body.
cilia crest a current moving mucous back up so it can be swallowed
acid
stomach - hydrochloric kills pathogens
vagina - lactic acid prevents growth of pathogens
2nd line of general defence system
destroys pathogens in body
Phagocytic white blood cells - surround and destroy pathogens
Defence proteins -
interferons - produced by cells infected by viruses - prevent the multiplication of virus
complements - 20 proteins found in blood plasma activated by infection, destroy viruses
Inflammation - results in redness, heat, swelling around site of infection - increases number of white blood cells in area
Phagocytic white blood cells
• when cells are damaged by invading micro organisms they release chemicals attracting white blood cells from blood stream
• white blood cells engulf and destroy bacteria/viruses
• these are called phagocytes
• large ones are called macrophages
where can macrophages be
move around in body fluids
remain in fixed places eg: spleen, lymph nodes and other lymphatic tissue eg tonsils, adenoids and appendix
Defence proteins
Complement - 20 proteins found in blood plasma, activated upon infection. destroys viruses and pathogens
Interferons - another set of defence proteins, prevent viral multiplication and help limit spread of virus infections such as colds or influenza
Inflammation
when cells are infected they release a chemical that results in blood capillaries dismaying causing localised swelling, redness and heat
brings more white blood cells to the area to fight infection
inflammation over the whole body?
causes increased body temperature/fever—— interferes with the ability of some bacteria and viruses to reproduce
specific defence system is also called the
immune system
specific defence system
attacks a particular pathogen
production of antibodies
white blood cells destroying infected cells (mono and lympho)
antigen
antigen id a foreign molecule that stimulates the production of antibodies
where are antigens found
they’re found on the surface of pathogens such as viruses and bacteria 🦠
antibody
a protein produced by white blood cells (lymphocytes) in response to an antigen (they inactivate antigens)
antibodies shape
they’re special Y shaped proteins produced by B-lymphocytes in response to antigens
monocyte
• develop into white blood cells called macrophages which recognise antigens present on surface of pathogens
• pathogens display antigens on their membranes stimulating the production of antibodies
lymphocytes
- attack body cells that display antigens on the surface (infected or cancer)
- produce antibodies
antibodies trigger …
the complement system which results in pathogenic cells being burst
induced immunity
the ability to resist disease caused by specific pathogens by the production of antibodies
active immunity
involves the production of a persons own antibodies in response to foreign antigens that enter the body
long term
natural active immunity
occurs when a pathogen enters the body in a normal way (infection)
vaccine
is a non disease causing dose of a pathogen which triggers the production of antibodies
passive immunity
occurs when individuals are given antibodies that weee formed by another organism
natural passive immunity
occurs when a child gets antibodies from its mother
artificial passive immunity
occurs when a person is given an injection containing antibodies made by another organism
immunisation
occurs when we produce or are injected with antibodies against a pathogen
two types of lymphocytes
B
T
b lymphocytes
made in bone marrow
matures in bone marrow
function: produce antibodies
t lymphocytes
made in bone marrow
mature in thymus gland
doesn’t produce antibodies
four types of T lymphocytes
helper T
killer T
Suppresser T
Memory T
Helper t cell
recognises antigens stimulates production of killer t cell
Killer t cell
kills foreign cells
Suppressor T cell
switched off immune system
Memory t cell
remembers the antigen
B cells
recognise the antigen
produce antibodies
After maturing in bone marrow where do b cells go
lymphatic tissue
spleen
lymph nodes
B cell is adapted to
one specific antigen present on surface of macrophage
produces one type of antibody (plasma B cells)
memory b cells
can survive years after infection is eliminated and can make specific antibody if same infection enters body
why is B better
produces antibodies in response to smaller amounts of antigen
much faster
greater numbers
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skin
lysozyme
clotting
mucous cilia
acid
why do i
white blood cells
defence proteins
inflammation
artificial active immunity
occurs when a pathogen is medically introduced into the body
vaccination
is the administration of a non disease causing dose of a pathogen to stimulate the production of antibodies
what kind of cells to Killer T cells destroy
Human cells with viruses in them or cancer in them
not pathogens
Plasma B cells produce…
antibodies
What stimulates the B cell and helper T cell?
macrophage with digested pathogen showing antigen on its membrane
