Immunity- pathogens and immunity Flashcards
are microorganisms always harmful? give an example
-no
-some can even be beneficial e.g. many types of bacteria and fungi are used in decomposition
what are 4 types of microorganisms?
-bacteria
-fungi
-Protoctista
-viruses
what is the term used to describe bacteria that is harmful?
-pathogen
what happens if a pathogen gains entry to the body?
-it can cause significant harm or even death
what is the bodies primary defense mechanism against these pathogens?
-try to prevent entry which is the body’s first line of defense
what is the body’s secondary defense mechanisms?
-specific and non specific response
what does non specific defense mechanism mean?
-these are not specific to individual types of pathogens
what is an example of a non specific defense mechanism?
-phagocytosis
what does specific immune response mean?
-this type of response does distinguish between individual pathogens and the response is tailored to the specific pathogen at hand
how long does specific immune response take and why is this?
-it takes a loner time to work compared to non specific but tend to provide long term immunity
what type of white blood cell is involved with specific immune response?
-lymphocytes
what are the 4 natural barriers to pathogen entry?
-an outer protective covering(skin)
-the enzyme lysozyme
-epithelial lining covered in mucus e.g. respiratory tract
-hydrochloric acid in the stomach
why is the skin a natural barrier to pathogen entry? when is the skin not an effective barrier?
-the skin provides a tough physical barrier that most pathogens cannot penetrate
-its not effective when its punctured e.g. cut or if its not in its healthy condition
what are the three liquid in which the enzyme lysozyme is secreted in?
-tears
-saliva
-sweat
how is the enzyme lysozyme used as a natural barrier to pathogen entry?
-its anti-bacterial as it is able to hydrolyze bacteria cell walls
-tears can also wash away debris and pathogens from the front of the eye which is very delicate
how is epithelial lining which is covered in mucus an effective barrier to pathogen entry?
-the mucus traps pathogens and prevents them penetrating the underlying membranes
what is a structure in the respiratory tract that prevents pathogen entry?
-cilia which sweep the pathogens back up the trachea
how is hydrochloric acid in the stomach an effective barrier to pathogen entry?
-this kills most pathogens that are in food
-it provides a very low pH that denatures the enzymes of the pathogens
what white blood cells are involved in phagocytosis?
-phagocytes
what do capillaries do as part of the inflammatory response?
-the capillaries in the area affected begin to leak plasma
-infected areas become swollen with dead pathogens and cell debris (pus)
-inflamed areas appear red due to increased blood flow to the area
inflammation causes the area to become hot, why is this good?
-the raised temp helps reduce infection by denaturing enzymes in the pathogen
what are the 2 types of phagocytes involved with phagocytosis?
-polymorphs which are the first to arrive
-macrophages which develop from monocytes and are larger and longer lived than the polymorphs
what are the 6 steps of phagocytosis?
-phagocyte moves to pathogen as its attracted by the chemicals it produces
-the phagocyte membrane invaginates to enclose the pathogen
-as pathogen is engulfed, the invaginated phagocyte membrane forms a vesicle around the pathogen
-lysosome move to vesicle and fuse with it
-hydrolytic enzymes within lysosome are released into the phagosome, these enzymes hydrolyze/ digest the pathogen
-the soluble digested products are absorbed into the cytoplasm of the phagocyte
how is specific immune response triggered?
-the responses are triggered by the body being able to recognize foreign cells
what are the two types of cells in the body?
-self and non self
what are non self tissues?
-cells that are not recognized by the body, if detected the body will produce an immune response
what part of non self tissues does the body recognize as foreign? what type of molecule mostly are these? what is the general term to describe these?
-a cluster of molecules that form part of the cell surface membrane that are recognized as foreign
-they are often proteins but can also be polysaccharides, glycolipids or glycoproteins
-antigens
why is the immune response specific to different non self tissues?
-because different pathogens have different antigens
why are lymphocytes used in specific response to tissues?
-lymphocytes have a receptor on its cell surface membrane that is complementary in shape to the antigen
-like lock and key theory
what is the definition of an antigen?
-chemicals/ molecules capable of producing a specific immune response
how do lymphocytes know what is self and non self?
-millions of lymphocytes with millions of receptors that are complementary to antigens
why is self specific immune response a slow process? (fetal example)
-in foetus these lymphocytes make contact with other foetal self cells
-the lymphocytes that are complementary in shape with foetal cells are switched off so that by the time the baby is born the functional lymphocytes that remain are those that are not complementary to self cells
-because there are millions of these lymphocytes remaining there is only a few of each type so this is the reason why specific immune response is slow
