Infection And Non-specific Immune Response Flashcards
Where is histamine released from and what does it do
Released by mast cells and damaged WBCs causing blood vessels to dilate (vasodilation) causing local heat and redness
-locally increase in temp reduced pathogen reproduction
-increase permeability of capillary walls allows plasma, WBCs and antibodies to move out of blood vessels and into infected tissue
When are interferons released and what do they do
When cells invaded by viruses they produce proteins called interferons, helps to prevent viruses spreading to uninfected cells by: preventing viral replication by inhibiting production of viral proteins, activating cells involved in specific immune response to kill infected cells and activate other mechanisms of non-specific immune response eg promote inflammation to bring immune system cells to site of infection
What is a phagocyte
A type of WBC that carries out phagocytosis, found in blood and tissues and are the first cells to respond to a pathogen inside the body
Process of phagocytosis
-chemicals released by bacteria/cells damaged at the site attract phagocytes
-phagocyte recognises antigens on pathogen and cytoplasm of phagocyte moves round the pathogen to engulf it
-pathogen now contained in phagocytic vacuole and a lysosome (containing lysozymes) fuses with the vacuole and the enzymes break down the pathogen into smaller antigens
-phagocyte then presents the pathogens antigens by sticking antigens on its surface to activate other immune system cells
-after few days area full of dead cells which form thick fluid (pus) can break through surface of skin/gradually broken down
What is a phagocyte displaying non-self peptides called
Antigen-presenting cell
What is an antigen
Any molecule the body recognises as not being of its own self
What are neutrophils
Phagocytes that leave blood capillaries by squeezing between the cells of capillary walls, ingest and destroy bacteria, last only a few days
What are lymphocytes
Two types:B and T cells, involved in the immune response including antibody production and immunity, some last only a few days and some for years
What are monocytes
Circulate in blood for a day before move into tissue by squeezing between cells of capillary walls where they become macrophages (can become APC) and engulf bacteria, foreign matter and cell debris. Are large cells with prominent nucleus
How does the lymphatic system prevent the spread of infection
-tissue fluid drains into the lymphatic vessels
-the fluid (lymph) flows along lymph vessels, passes through lymph nodes and eventually returns to blood via lymphatic and thoracic ducts
-as lymph passes through lymph nodes any pathogens present activate lymphocytes and macrophages which destroy them
