immunity lowkey Flashcards
What are the types of non-cellular pathogens?
Viruses and prions
Give two examples of physical barriers in plants
Waxy cuticles on leaves to prevent pathogenic entry.
Presence of thorns or trichomes to deter insects and grazers.
Give two examples of chemical barriers in plants
Oxalic acid, toxic to some organisms if ingested.
Chitinases, enzymes that have antifungal properties.
Give two examples of physical barriers in animals
Intact layer of dead skin which prevents pathogens from infecting live cells.
Mucus secretions which trap pathogens and prevent orificial entry.
Give two examples of chemical barriers in animals
Lysozymes in tears have antibacterial properties and prevent bacterial invasion.
Stomach acid, very low pH destroys many pathogens by denaturing the functional tertiary structures of their essential enzymes.
What are phagocytes and how do they work?
Phagocytes are leukocytes that engulf non-self cells by endocytosis and digest them using lysosomes.
What are the three types of phagocytes?
Neutrophils, Macrophages, Dendritic cells.
What are cytokines?
Cytokines are signalling molecules that stimulate, recruit, and proliferate immune cells and guide them to sites of infection or injury.
What are macrophages?
Macrophages are phagocytes that engulf pathogens and display pathogenic antigens on their surface MHC II markers.
What are the three types of antigen presenting cells?
Macrophages, B- cells and dendritic cells.
What are dendritic cells?
Dendritic cells are phagocytes that engulf pathogens and display pathogenic antigens on their surface MHC II markers.
What are natural killer cells?
Natural killer cells are immune cells that identify and destroy abnormal or cancerous cells by detecting missing/abnormal MHC I markers on their surface.
- found in blood/lymph
- kill virus-infected cells
What are interferons?
Interferons are cytokines released from virally infected cells that interact with receptors on normal cells and make them less susceptible to viral infection.
- signal change in plasma membrane making entry of virus more difficult (make PM less fluid)
- signals neighbouring uninfected cells to prepare to destroy RNA to reduce protein synthesis
- signal neighbouring infected cells to undergo apoptosis
- activates immune cells such as NK cells
What are the three major outcomes of a complement cascade?
Opsonisation, Chemotaxis, Lysis
What is a complement cascade?
A complement cascade is activated when they make direct contact with molecules on the surface of pathogens
- it is a series of complex reactions where complement proteins interact with each other to deal with pathogens, and can result in opsonisation, chemotaxis, or lysis
Describe the process of opsonisation.
Opsinisation occurs when antibodies or complement proteins stick to the surface of pathogens flagging them for phagocytosis.
Describe the process of chemotaxis.
Chemotaxis is the process of complement proteins gathering near pathogens to attract phagocytes to them, increasing the chances of phagocytosis
Describe the process of lysis with respect to complement proteins.
Lysis occurs when complement proteins join together and form a membrane attack complex (MAC), which creates membranal pores and destroys the pathogen cell.
What are the three main stages of inflammation?
- Initiation
- Vasodilation
- Migration
What occurs during vasodilation with respect to inflammation?
During vasodilation, histamine released from mast cells causes blood vessels to dilate and increases blood flow to injury site, which can cause swelling, redness and warmth associated with inflammation.
What occurs during migration with respect to inflammation?
During migration, phagocytes are guided by cytokines to the site of injury and complement proteins opsonise pathogens to increase chances of phagocytosis, platelets travel to the site to block wounds → important for clotting,
- pus indicates that this stage is occurring
–> consists of mainly dead immune cells, tissue and pathogens
What are the three main roles of the lymphatic nervous system?
- Transportation of antigen-presenting cells to secondary lymphoid tissues for antigen recognition and initiation of the adaptive immune response.
- Production of leukocytes
- Removal of fluid from tissues around the body.
What are the three major components of the lymphatic nervous system?
- Primary lymphoid tissues
- Secondary lymphoid tissues
- Lymphatic vessels
Where are B and T cells produced?
B and T cells are produced in primary lymphoid tissues found in bone marrow.