Which of the following are involved in the bodys first line of defense against infection
Updated 10th March 2021 The immune system plays a vital role in protecting people from harmful pathogens, such as viruses and bacteria, that could cause infection. Show In order to destroy invading pathogens and protect us from infection, the immune system has to be able to differentiate between self antigens, i.e. molecules that belong on the cell’s surface, and non-self antigens, i.e. what is foreign to the body. There are two branches of the immune system: innate (or natural) immunity and adaptive (or acquired) immunity. These two arms work both independently of each other and together. Innate immunityInnate, or natural, immunity is present from birth and is the body’s first line of defence. It comes into play immediately or within a few hours of an antigen appearing in the body. It’s the natural response we have upon recognising a foreign cell or microorganism – and is non-specific, which also means it is unchanging and will not generate long-lasting immunity. The human body has a number of non-specific physical and biochemical defence mechanisms to protect it from infection. Mechanical defence mechanisms of the innate immune response include:
When these natural defences are breached, such as in the case of a wound or burn, microorganisms are still able to enter the body. If microorganisms do enter the body, the innate immune system initiates two main defensive strategies within minutes of the attempted invasion. These biochemical defence mechanisms of the innate immune response include:
The actions of the innate immune system are usually sufficient to destroy invading microorganisms. Adaptive immunityThe adaptive, or acquired, immune response comes into play when the innate immune response has failed to destroy an invading microorganism. Unlike the innate immune response, it is highly specific and adaptive. It targets specific antigens and will adapt its response permanently to prevent the body from becoming reinfected with the same microorganism in the future. While the acquired immune response is highly effective, it is however much slower than the innate immune response. It can sometimes take 7-10 days to fully mobilise. Activation of the adaptive immune responseBranch-like cells found in the skin, known as macrophages and lymphocytes, play a key role in activating the immune response. Lymphocytes are white blood cells which originate in the bone marrow but settle in lymphoid organs such as the thymus. When a foreign antigen enters the body it will eventually meet a lymphocyte with a matching receptor. The cell with the ‘best fit’ then divides to produce a large number of clones which are mobilised to attack the microorganism. There are three groups of antigen-receptor cells that specifically recognise foreign ‘non-self’ antigens as part of the adaptive immune response:
The complement system plays an important role in enhancing the effect of antibodies. It can be activated by the lectin pathway, the mannan-binding lectin (MBL) pathway or the classical pathway. While largely very effective at destroying microorganisms that invade the body, the adaptive immune system can sometimes generate ‘anti-self’ receptors. And if not destroyed, these ‘anti-self’ receptors can lead to autoimmune diseases, such as type 1 diabetes, rheumatoid arthritis, coeliac disease and narcolepsy. Covid-19, the immune system, and the importance of vaccinationThe aim of vaccinations is to safely teach our adaptive immune systems to repel disease. This is why vaccines for diseases like Covid-19 are so vital. What is the body's 1st line of defense against infection?The innate immune system is the body's first line of defense against germs entering the body. It responds in the same way to all germs and foreign substances, which is why it is sometimes referred to as the "nonspecific" immune system.
What are the 3 body's defenses against infection?These specialized cells and parts of the immune system offer the body protection against disease. This protection is called immunity. Humans have three types of immunity — innate, adaptive, and passive: Innate immunity: Everyone is born with innate (or natural) immunity, a type of general protection.
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