LEAVING CERT BIOLOGY THE HUMAN DEFENCE SYSTEM Flashcards
some information is too long so it has to be read in the book
define a pathogen
a pathogen is a foreign body or cell that causes disease
what do pathogens include
bacteria, viruses and fungi
what two defence systems do humans use to help defend themselves against pathogens
the general defence system and the specific defence system
define the general defence system
the general defence system tries to defend us against all pathogens
briefly explain how the general defence system works
the general defence system acts by preventing the entry of pathogens into the body or by destroying them when they do enter
name 6 things from the general defence system that prevent entry of pathogens
skin, lysozyme, clotting, mucus, cilia and acid
name 4 things from the general defence system that destroy pathogens in the body
white blood cells, complement, interferons and inflammation
how does the skin prevent the entry of pathogens
skin acts as a barrier to the entry of pathogens
how does lysozyme prevent the entry of pathogens
lysozyme is an enzyme that is found in sweat, tears, saliva and urine. It bursts the walls of bacteria, leading to their death
how does clotting prevent the entry of pathogens
clotting helps to prevent the entry of pathogens once our skin is damaged
how does mucus prevent the entry of pathogens
mucus in the respiratory system is sticky. it traps pathogens
how does cilia prevent the entry of pathogens
cilia in the respiratory system sweep the mucus up from the air passages. the mucus and the pathogens then passes to the stomach
how does acid prevent the entry of pathogens
acid in the stomach [hydrochloric acid] destroys pathogens. lactic acid in the vagina acts in the same way
how do white blood cells destroy pathogens in the body
white blood cells surround and destroy pathogens that enter the body. these cells are often called phagocytes. large phagocytes are called macrophages
how does complement destroy pathogens in the body
complement is a set of proteins found in the plasma. complement is activated by infection and causes bacterial cell walls to burst
how do interferons destroy pathogens in the body
interferons are another set of proteins. they are produced by body cells that become infected by viruses. interferons prevent the multiplication of viruses
how does inflammation destroy pathogens in the body
inflammation results in heat, redness and swelling around the site of infection. this increases the number of white blood cells in the area of infection. if the inflammation occurs all over the body it is called a fever
define the specific defence system/ the immune system
the specific defence system/ the immune system acts against one type of pathogen or antigen
define Antigen
an antigen is a foreign substance that stimulates the production of antibodies
define antibody
an antibody is a protein produced by white blood cells in response to an antigen
antigens are antibody generating molecules. yes or no
yes
where are antigens found
antigens are found on the surface of pathogens such as viruses and bacteria
what are antigens associated with
antigens are associated with pollen grains, blood transfusions, transplants and cancer cells
where are B cells made and mature
bone marrow
what happens to B cells once they mature
B cells move to the lymph nodes
what do B cells produce
antibodies
where are T cells made, mature and activated
made in bone marrow, mature and activated in the thymus gland
where is the thymus gland located
the chest
what do T cells not produce
antibodies
name two types of lymphocytes
b cells and t cells
what type of cells are lymphocytes
white blood cells
name four different types of T cell
helper T cells
killer T cells
suppressor T cells
memory T cells
what do helper T cells do
helper T cells recognise antigens on monocytes
what do killer T cells do
killer T cells attack and destroy abnormal body cells
what do suppressor T cells do
suppressor T cells inhibit B cells and killer T cells
what do memory T cells do
memory T cells stimulate B cells and killer T cells to multiply if the same antigen enters the body again
what is induced immunity
induced immunity is the ability to produce antibodies against specific antigens
what is active induced immunity
active induced immunity means that the body produces its own antibodies
what are the two types of active induced immunity.
natural and artificial
define a vaccine
a vaccine is a non reproductive does of an antigen designed to stimulate antibodies
define passive induced immunity
passive induced immunity happens when antibodies pass from one organism to another [usually from the mother to her baby]
name two types of passive induced immunity
natural and artificial
