Immune defences functions and challenges Flashcards
What is the primary function of immunological defence?
To eliminate pathogens, minimise body damage
What cells defend against intracellular pathogens eg. viruses?
Cytotoxic T cells
What cells defend against extracellular pathogens eg. bacteria, small parasites, fungi?
Phagocytes
What cells defend against large parasites?
Mast cells, eosinophils
What are immune privileged areas?
Anatomical areas where there is naturally no immune response, as they can tolerate antigens introduced without immediately triggering immune response
Why is there no immune response in immune priviledged areas?
less risk of being potentially damaged by inflammatory response to pathogens
Give 4 examples of immune priviledged areas
Eyes, CNS, placenta, testes
What are commensals?
Microbes that reside in body or on mucous surfaces without harming human health, so they are tolerated
What are 3 functions of commensal bacteria in the stomach?
Provide essential nutrients, aid metabolism of indigestible compounds, defend against colonisation of opportunistic pathogens
What is the primary response?
Immune response to first exposure of a specific pathogen
How long does it take for the primary response to become active?
Days to weeks
What occurs in the time taken for the primary response to activate?
Symptoms of disease, production of antibodies and memory B cells
What is the secondary response?
Immune response to subsequent exposure of a previous pathogen
Why is the secondary response quicker to activate?
Memory B cells produced from primary response can respond very fast
Does secondary response activation time cause disease symptoms?
No, because antibodies are produced before symptoms develop
What is immune dysregulation?
non-balance between immune response activation and suppression
What is hypersensitivity and what are the classes?
Overreaction to benign antigens with classes from type I-IV
What is autoimmunity?
Immune response against self-proteins or tissues, caused by tolerance breakdown
What is tolerance?
Mechanisms used to distinguish between ‘self’ and ‘non-self’ cells
Why is multiple sclerosis an autoimmune disease?
Immune response against myelin sheaths of neurons in CNS which causes neurological dysfunction
Why is Crohn’s disease an autoimmune disease?
Immune response against gut epithelium and microbiota, causing poor nutrient absorption from food
What is immunodeficiency?
Failure to protect against foreign antigens
How can innate or adaptive immunity cause immunodeficiency?
One of their components is absent or defective
What is the difference between primary and secondary immunodeficiency?
Primary is inherited but secondary is caused by an external agent
