Essay On The Lung And The Lungs

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The lungs are the main organs of the respiratory system. Their function is to regulate gas exchange. They are located in the thorax. They are connected to the trachea which conducts inhaled air through its tubular branches, called bronchi. The bronchi then divide into smaller and smaller branches (called bronchioles). The bronchioles eventually end in small air sacs called alveoli. It is in alveoli that occurs the gas exchange. Lungs are in contact with airway microorganisms and elements like tobacco. Therefore they have to be as clean as possible. To garantee their sterility, lungs need the action of the innate immune system. This section will describe immune cells present in the lung. The immune system is a set of different structures and …show more content…

The main difference between both immunities resides in their specificity. The adaptive immune system (called as well acquired immune system) creates a memory after a first interaction with pathogens. It detains the ability to recognise specific elements of a pathogen (called antigens) in order to eliminate them. Therefore, the acquired immune system will create antibodies able to interact with these antigens (Janeway et al., 2005). Thus, it evolves through the life as opposed to the innate immunity. On the other hand, the innate immunity fails to have a memory and is only able to detect same patterns found in pathogens. They are called Pathogen Associated Molecular Patterns or PAMPs (Kawai, 2010). This chapter will focus only on the innate immune system. The innate immune system The innate immune system is considered mostly as universal as it is present in most of the organisms on Earth. It is characterised by the ability to react fast (as opposed to the adaptive immunity, which can take up to several days to be active) to any external threats. The innate immune system has three components : physical, cellular and humoral (figure 1) (Beutler, 2004). Figure 1. The different cellular and humoral components of the innate immune system (Beutler, …show more content…

They are activated in cascade upon recognition of microorganisms. They are responsible for the opsonisation of the pathogens which will be sent for phagocytosis (Dunkelberger, 2010). The complement is composed of three pathways : the classical, the alternative and the Mannose Binding Lectine (MBL) pathways. Different proteins are involved in these pathways (Dunkelberger, 2010). The classical pathway is induced when the protein C1 interacts with a complex antibody/antigen. The alternative pathway is induced when the protein C3 interacts with some bacterial components. The MBL pathway is induced when the Mannose Binding Protein interacts with some bacterial elements. The three pathways induced the membrane-attack complex (figure

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