the human defence system Flashcards
pathogen
an organism that causes disease
immunity
the ability to resist infection
general defense system
acts as a barrier to all pathogens that attempt to gain entry to the body
specific defense system
attack particular pathogens
antigen
foreign molecule that stimulates the production of antibodies
antibody
protein produced by wbc in response to specific antigens
induced immunity
ability to resist diseases caused by specific pathogens by the production of antibodies
active immunity
involves the production of a person’s own antibodies in response to foreign antigens that enter the body
artificial active immunity
occurs when a pathogen is medically induced into the body
first line of general defence system
skin
clotting
sebacous glands
lysozyme
mucuos
cilia
acid
beneficial bacteria
skin
acts as a physcial barrier to the entry of pathogens
lysozyme
enzyme in tears, sweat and saliva that attacks and dissolves the walls of bacteria
sebacous glands
in the skin produce sebum
chemicals found in sebum kill bacteria
mucus
most body systems are lined with sticky mucus
pathogens are trapped by mucus and prevented from entering the body
cilia
tiny hairs that beat and create a current which moves mucus back up the respiratory system so it can be swallowed into the stomach
coughing clears mucus an pathogens from throat
acid
HCL in the stomach kills many pathogens
beneficial bacteria
bacteria in the vagina produce lactic acid which prevents the growth of pathogens
second line of general defence
phagocytic white blood cells defence proteins
phagocytic white blood cells
- when cells are damaged by invading micro-organisms they release a large number of chemicals
-the chemicals attract white blood cells from the bloodstream
-white blood cells engulf and destroy any bacteria , viruses or other micro-organisms that they meet
-macrophages move around the body in bodily fluids and act as scavengers for pathogens
-other macrophages remain fixed and filter out and destroy pathogens that are present in lymph
defence proteins
complement is a set of 20 proteins in the blood plasma activated by infection these destroy viruses and other pathogens
interferons prevent viral multiplication and help to limit the spread of virus infections
inflammation
when cells are infected they release a chemical that results in blood capillaries dilating and becoming more porous
this causes swelling. redness, heat and pain
it brings more WBC to the area to fight infection
it causes increased body temperature
Higher temperatures interfere with the ability of bacteria and viruses to reproduce
