communicable disease + biodiversity Flashcards
what are the primary non specific defences in animals against pathogens
- skin (has healthy mircroorganisms that outcompete pathogens for space, sebum and oily sub also inhibits growth of pathogens
- blood clotting
- wound repair
- inflammation
- expulsive reflexes like sneezing
- mucous membranes- traps pathogens and contains lysosomes and phagocytes
- lysosomes in tears and urine and stomach acid
what are the roles of cytokines
attract white blood cells/ phagocytes to site of infection
these act as cell signalling molecules informing other phagocytes that the body is under attack making them move to site of infection/ inflammation.
increase body temperature and stimulate the specific immune system
what are the roles of opsonins
chemicals that bind to pathogens
what are the roles of phagosomes and lysosomes
when a phagocyte has engulfed a pathogen the vacuole it encloses it in is called the phagosome
this will combine with lysosomes to form a phagolysosome where enzymes will digest and destroy the pathogen
what is the structure of phagocytes
specialised white blood cells that engulf and destroy pathogens
two types- neutrophils and macrophages
how do phagocytes work
they build up at the site of infection as they are attracted by chemicals produced by pathogen
- they recognise the pathogen as non-self and bind to it
- they then engulf to form phagosome
how is blood clotting a defence
blood clots seal the wound to stop pathogens getting in
when platelets come into contact with collagen in skin or wall of damaged blood vessel they ADHERE and secrete substances like thromboplastin and serotonin
collagen fibres deposited too to give new tissue strength. Once the epidermis reaches normal thickness the scab falls off
how is inflammation a defence
localised response to pathogens/ or irritants
characterised as pain, redness,swelling
activates MAST cells which release histamines and cytokines
what are neutrophils and what is their purpose in immune response
white blood cell with lobed nucleus to fit through tight places to get to site of infection
A type of immune cell that is one of the first cell types to travel to the site of an infection. Neutrophils help fight infection by ingesting microorganisms and releasing enzymes that kill the microorganisms. A neutrophil is a type of white blood cell, a type of granulocyte, and a type of phagocyte.
what is an antigen presenting cell and how is it made
and what is a MHC
macrophages take longer to engulf and destroy bacterium than neutrophils but it is more complex
when digested a pathogen, the macrophage combines antigens from pathogen surface membrane with special GLYCOPROTEINS in the cytoplasm called MHC or major histocompatability complex which moves these pathogens antigens to the macrophages own surface membrane to become an antigen presenting cell
what are thromboplastin and seretonin
> thromboplastin is an enzyme which triggers the blood clotting cascade to form a blood clot/ thrombus
(makes prothrombin becomes thrombin along with Ca2+ ions)
> serotonin makes smooth muscle walls of blood vessels contract so they narrow and reduce blood supply
what are histamines
secreted by mast cells,
they make blood vessels dilate causing localised redness and heat as inc. temp prevents pathogens reproducing
>they make blood vessels more leaky so blood plamsa forced out which makes tissue fluid which causes swelling and pain
what does thrombin catalyse
the reaction which makes fibrin from fibrinogen
what is the purpose of antigen presenting cells
stimulate other cells involved in the SPECIFIC immune system response
what is the structure and role of T helper cells
have CD4 receptors on their cell surface membranes which bind to the surface antigens of antigen presenting cells
-they produce interleukins
what is the structure and role of T killer cells
these destroy the pathogen carrying the antigen
> they produce the chemical perforin with kills pathogens by making holes in the surface membrane so it is freely permeable
what is the structure and role of T memory cells
live for a long time and are part of the IMMUNOLOGICAL MEMORY
if these meet an antigen a second time they divide rapidly to form clones of T killer cells and destroy pathogen
what is the structure and role of T regulator cells
supress the immune system
act to control and regulate it
they stop the immune response once a pathogen has been eliminated to make sure the body recognises self antigens and doesnt set up an autoimmune response
interleukins also important in this control
what is the structure and role of plasma cells
this produce antibodies for a particular antigen and release them into the circulation
an active plasma cell only lives for a few days but produces many antibodies a second while alive+active
what is the structure and role of B effector cells
these divide to form plasma cell clones
what is the structure and role of B memory cells
live for a VERY LONG TIME
provide immunological memory
remember a specific antigen and enable body to make a very rapid response when encountering a pathogen with that antigen again
what are interleukins
they are produced by T helper cells and are a type of cytokine
>they stimulate the activity of B cells which increases antibody production and production of other T cells
> also attract and stimulate macrophages to ingest pathogens with antigen -antibody complex
