Module 2 - Branches of the IS Flashcards
3 immune barriers of the innate immune system
physical, cellular, soluble
Physical immune barrier
made of every structure located at the interface between the inside and outside of the body
examples of physical barriers
skin, cilia, bodily secretions
Cellular immune barrier
made of the cells which play a role in the innate immune response
examples of cellular imune barriers
neutrophils, macrophages, dendritic cells, NK cells
soluble immune barrier
made of macromolecules that contribute to the mediation of an innate immune response
examples of soluble immune barriers
complement and cytokines
primary function of physical barrier
prevent or slow down the invasion of pathogens
physical components of the physical immune barrier
skin & mucous membranes
mucous membranes
-cover the cavities of the body including the respiratory, gastrointestinal, urinary and reproductive tracts
-contain specialized cells like cilia and produce mucous
primary function of cellular barrier
prevent or slow down the invasion of pathogens that have broken through the physical barrier
four major cell types that play a key role in innate immune response processes (imflammation and phagocytosis)
neutrophils, macrophages, dentritic cells and natural killer cells
Chemical components of the physical immune barrier
tears, saliva (activate antimicrobial substances like lysozyme) and gastric acid (destroys bacteria and toxins)
Neutrophils
-most common leukocyte found in mammals
-phagocytes that patrol the body to find, engulf and destroy pathogens
-circulate in blood for 12h before entering tissues via diapedesis
-recruited to site of infection by macrophages
-lifespan of 1-3 days after entering tissues
Diapedesis (extravasation
process by which blood cells (like neutrophils) move from blood to tissues by passing through intact vessel walls.
Macrophages
-phagocytes that patrol the body to find, engluf and destory pathogens
-can either take up residence in specific tissue or move freely
-contribute to tissue repair & present antigens to other immune cells (T-cells)
-activated after phagocytosing pathpgens or in response to cytokine signalling
Dendritic Cells
-phagocytes that are often in contact with the external environment
-engulf foregin antigens that have invaded initial barriers
-present antigens on their cell surface through peptide MHC complexes which can be recognized by helper T cells
-major link between adaptive and innate IS
Natural Killer Cells
-recognize abnormal cells lacking antigen specific receptors
-destroy abnormal cells of the body, which include tumourous and virus infected cells
-bind to cell surface of target cells and release chemicals causing pores to form in the cell membrane, leading to their lysis
two major categories of macromolecules in the soluble barrier
complement system and cytokines
Importance of soluble barrier components
developing inflammatory innate immune response, induced following penetration of infectious agent through physical barriers
what is the complement system made of
over 30 soluble proteins
where is the complement system
complement proteins circulate in the blood, normally in the inactive form
When is the compliment system activated?
directly activated in the presence of extracellular pathogens or indirectly by pathogen-bound antibody
How is the compliment system activated?
activation induces reactions between complement proteins, leading to the formation of a membrane attack complex (MAC) and complements the efficency of other immune functions such as inflammation and phagocytosis