Immune Response Flashcards
What happens when an antigen enters body
When an antigen enters body (non self), it triggers an immune response which is specific or non specific
How does body prevent entry of antigens
Body uses external barrier skin and mucous membranes to prevent entry of microbes
What are specific and non specific immune responses
Specific immune responses are B cells (which produce antibodies) and T cells are produced and kill microbe.
Non specific immune response is antimicrobial proteins e.g lysozyme are synthesised to defend body against microorganisms. Inflammation occurs. Effective against a wide range of infectious agents, does not involve recognition of infectious agent and does not react to specific antigens.
What is a lysozyme, where is it found and how does it do its function
Lysozyme is an enzyme that kills bacteria by breaking down their cell membranes (by hydrolysing the polysaccharide in cell wall, usually peptidoglycan). Found in tears, saliva and nasal secretions
What is inflammation
Inflammation is when damaged white blood cells and mast cells release histamine, causing vasodilation, increasing blood flow into capillaries and permeability of capillaries increase so vessel leaks. Plasma fluid, white blood cells and antibodies leak out from blood into tissue, causing oedema.
What is phagocytosis
Phagocytosis is when bacteria with antigens enter, macrophage/neutrophil identifies antigen as non self (using receptors). They form projections around bacteria then engulf bacteria (by endocytosis) and they enclose bacteria in a vacuole. Lysosomes fuse with vacuole, releasing enzymes that destroy foreign material e.g dust
What are phagocytes and what are the 2 types
Phagocytes are white blood cells that engulf bacteria, 2 types are neutrophils and macrophages.
What are neutrophils
Neutrophils are white blood cells that are small 9um diameter and the are identified by lobed nucleus. First cell to arrive in response to chemical signal by damaged bacteria (histamine) Engulf 5 to 20 bacteria. Make up 70% of WBC
What are macrophages
Macrophages are white blood cells that are larger 15-20um diameter and have a very round nucleus. Appear after neutrophils but can destroy 100+ bacteria. They engulf damaged cells and foreign matter e.g dust in lungs. 4% of WBC
Where are lots of macrophages found
Lots of macrophages are found in lungs, liver, kidney, spleen and lymph nodes.
What is inflammation caused by
Inflammation is caused by an injury e.g cut or graze enables microbe and other foreign material to enter body. Blood clot will rapidly seal wound
What is infection
Infection is when microorganism finds its way into tissues
