M7: Animal responses to pathogens Flashcards
what is included in the first line of defence?
physical barriers, physical responses, chemical barriers
What are physical barriers against infection?
passive innate barriers
- skin, mucous membrane, mucous, cilia, sphincters, peristalsis
What are some examples of physical responses to infection?
- granuloma
- vomiting and diarrhea
- increased urination
- wound healing
What are some chemical barriers against infection?
- urine
- sebum and sweat
- saliva
- tears
- gastric excretions
what is involved in the second line of defence?
- antigens, chemical responses,
what are antigens?
- protein markers that recognise things as foreign or belonging. If foreign, it activates the immune response.
examples of chemical responses in the second line of defence?
inflammation, phagocytosis, complement system, cytokines, pyrogens
what is the process of inflammation?
- triggers redness, swelling, pain, and heat through the release of chemicals - (histamine, serotonin, bradykinin). This acts as an alarm that causes capillaries to dilate.
process of phagocytosis?
- phagocytes change shape to engulf pathogens, once done enzymes are released to destroy them. mostly macrophages.
what is the complement system?
- a group of 20 soluble proteins that assist in destroying pathogens
roles of complement system?
- attracts phagocytes to infection and stimulates them to be active
- destroys membranes of invading pathogens
what are cytokines?
chemical messengers that are produced during an infection
roles of cytokines?
- promote development of and differentiation of immune cells
- form a link between innate and adaptive immune system
- burst from infected cells causes nearby unaffected cells to release cytokines.
what are pyrogens?
fever causing chemicals
process of pyrogens?
- cytokines send signals to the brain to increase overall body temperature, increase white blood cells and limit the growth of pathogens.
examples of cells involved in the second line of defence?
- neutrophil
- macrophage
- natural cell killer
- dendritic cell
neutrophil?
release toxins to neutralise or inhibit the growth of bacteria or fungi
macrophage?
phagocytosis of pathogens and cancer cells, antigen-presenting.
natural killer cell?
kills tumour cells and virus-infected cells.
dendritic cell?
an antigen-presenting cell that triggers an adaptive immune response.
what is innate immunity?
1st and 2nd line of defence
what is adaptive immunity?
3rd line of defence
when is cell-mediated response used?
pathogens infect cells
when is a humoral response used?
pathogens outside cells
T cell? and types?
- destroy intercellular pathogens
- helper, killer, memory, suppressor
B cells? and types?
- produce antibodies and destroy extracellular pathogens
- plasma, memory
what is involved in cell-mediated immunity?
- intracellular bacteria
- macrophages/dedndrites present bacterial antigens on their surface
- helper cells stimulate cytotoxic T cells
what is involved in humoral immunity?
- extracellular bacteria
- macrophage/dendrites present bacterial antigens on the surface
- helper T cell stimulates production or plasma b cells
roles of memory cells?
primary immune response > antibody-producing plasma and cytotoxic cells are stored and stored for the next encounter
secondary immune response > when exposed again, more rapid and reproduces more antigens
