ANIMAL defense Flashcards
What are the (non specific) defences ?
Barriers
Blood clotting
Inflammatory response
Expulsive reflex
Barriers
Skin
Mucuous membranes
Tear fluid- lysosomes and antibodies
HCl- Acidity of stomach denatures bacteria
Ciliated epithelium- Tiny hair like structures tat waft pathogens containing musuc, swallowed and passed down digestive system
Barriers - skin
Outer barrier to infection, epirdermis, outer layer covered in helathy mirognasims, produces SEBUM - oily substances inhibiting pathogen growth
Barriers- Mucuous membranes
Airways, lings, digestive system and reprodutive tracts, lined wtih mucous membranes
Secrete mucous(goblet cells)
Trap pathogens and contain lysosomes that destory bacterial and fungal ell walls
Contains phagocytes who remove remaining pathogens
Blood Clotting
If you cut yourself, skin is breached and pathogens can enter the body
The blood clots to seal wound
When platelets come into contact with collagen in the skin, ahere and secrete substances = clot
Clot dries out, forming a tough scab , epidermal cell blow the scab start to grow, sealing the sound
Collagen fibres deposited to give the new tissue strength
Once the new epidermis reached normal thickness , scab sloughs off
Chemicals involved with blood clotting
Thromoboplastin - enzyme that triggers a cascade of reactions resulting in blood clot forming ( thrombin)
Serotonin- Makes the smooth muscle in blood vessel walls contract, narrowing and reducing blood supply to the area
Fibrogen — fibrin– forms clot
Inflammatory response
Response to pathogen resulting in inflammation at SITE OF WOUND
Characterized by pain, heat, swelling,
Mast cells activated to damaged tissue - release hsitmaines adn cytokines
Histamines
Make blood vessels dialate, causing localised heat and redness
Raised temperature helps prevent pathogens reproducing
Make blood vessel walls more leaky so blood plasma is forced out, Once forced outm blood is known as tissue fluid and it causes swelling
Cytokines
Attract white blood cells( phagocytes) for phagocytosis
Secondary non specific defenses
Fevers
phagocytosis
Fevers
Cytokines stimulate hypothalamus to reset the thermosat and your temp goes up
Most pathogens reproduce best at /below 37 -inhibits pathogen reproduction
The specific immune system works faster at higher temps
Denature enzymes or bacteria
What are phagocytes
Specialized white blood cells that engulf and destroy pathogens
2 main types- macrophages and neutrophils
Phagocytes - at site of infection and attack pathogens , Sometimes can see pus in wound ( contains dead phagocytes
Macrophages
When a macrophage has digested a pathogen, combines antigens from the pathogen surface membrane with special glycoproteins in the cytoplasm called the major histocompatibility complex ( MHC)
MHC moves the antigens to teh macrophages own cell surface becoming an antigen presenting cell
Antigens stimulate other cells involved in specific immune system
Phagocytosis
- Pathogens produce chemicals that attract phagocytes
- Phagocytes recognize non human proteins on pathogens
- Phagocyte engulfs the pathogen and encloses it in a vacuole called a phagosome
- the pahgosome combines with a lysosome to form a phagolysosome
- enzymes from the lysosome digest and destroy
How long does it take for neutrophils and macrophages to engulf and destroy pathogens
10 minutes for neutrophils
LONGER for macrophages
What are antibodies
Y shaped glycoproteins
Immunoglobulins
Bind to a specific antigen on pathgoen or toxin thats triggered reponse
MAde up of 2 polypeptide chains called heavy chains adn 2 shorter light chains
Disulphide bridges within polypeptide chains holding them togerhe and holding chains together
Variable and constant regions - antibodies
The binding site of 110 minoa cids on both teh heavy and light chains = VARIABLE
Gives it its specificity
What happens when antibody binds to antigen
Antibody-antigen complex
Lock and Key
3 types of antibody
Opsonins
Aglutinins
Neutralisation ( antitoxins)
Opsonins
The antibody of the antigen -antibody complex acts as an opsonin so teh complex is easily engulfed and digested by phagocytes
Pathogens can no loner invade
Antitoxins
Binding to toxins produced by pathogens and making them harmless
Algutinins
Cause the pahtogen carrying antigen-antibody compexes to clump together
Helps to prevent them spreading through teh body and makes it easier for pahgocytes to engulf a number at a time
What are lymphocytes
Highly specialised cells produced by the bone marrow
B lymphocytes
Mature and produced in bone marrow 10 million different types Divide by mitosis Plasma cells B effector cells and B memory cells
T lymphocytes
Produced in bone marrow and MATURE in thymus gland
Repond to organism own cell which has been invaded
T helper, Killer, Memory, regulator
Plasma cells
Produce antibodies to a particular antigen , release them into circulation
Lie for a few days, produce 2000 anitbodies per second
B effector cells
Divide to form plasma cell clones
B memory cells
Live for long time
Immunological memory
Programmed to remember a SPECIFIC antigen and enable the body to make a rapid response when a pathogen carrying that antigen is encountered again
T helper cells
Have CH4 receptors on their cell surface membranes which bind to surface antigens on apc's Produce interleukin(type of cytokine, cell signalling molecule) Interleukin's stimulate activity of B cells, which increases antibody production, stimulation production of other types of T cell , attracts and stimulates macrophages to injest pathogens with antigen antibody complexes
T killer cells
Destroy the pathogen carrying antigen
Produce perforin kills pathogens by making holes i the cell membrane so its freely permeable
T memory cells
Live for a LONG time
Part of immunological memory
If you meet athogen for a second time - divide rapidly to form clones of t kiler cells to kill pathogens
T regulator cells
These cells suppress teh immune system, acting to control and regulate it
Stop the immune response one a pathogen has been eliminated and make sure the body recognizes self antigens and doesn’t set up an autoimmune reponse
What is cell mediated immunity
T lymphocytes respond to cells of an organism that has been changed in some way
WHAT happens in cell mediated immunity?
Macrophages digest and engulf pathogens in pahgocytosis, they process the antigens form the surface of the pathogen to form APC’s
The receptors on some of the T helper cells fit the antigens, these t helper cells become activated and produce interleukins, which stimulate more T cells to divide rapidly by mitosis
They form clones of identical activated T helper cells that carry the right antigen to bind to a particular protein
What happens to cloned T cells in cell mediated immunity
- Develop into T memory cells, which give a rapid response if this pathogen invaded body again
- Produce interleukins which stimulate B cells to divide
- Simulate the development f a clone of T killer cells that are specific for the presented antigen and then destroyed infected cells
Humoral immunity ?
Body respnds to antigens found OUTSIDE cells(e.g. Bacteria and fungi)and to APCS
Produces antibodies
Antibodies not attached to cells
What Is an APC - humours immunity
When a B cell with complimentary antibodies binds to antigens
B cell engulfs and processes the antigens to become an APC
What happens in humoral immunity?
- Activated T cells bind to the B cell APC - CLONAL selection, the B cell with the correct antibody to overcome a particular antigen is secreted for cloning
- Interleukins produced by the activated T helper cells activate the B cells
- The B cell divides( mitosis) to give clones of plasma cells and B memory cells = CLONAL expansion
- Cloned plasma cells produce antibodies that fit antigens , disable them and act as opsonises or aggultonins
- Some cloned B cells develop int memory cells, if the body is infected by the same pathogen again - b memory cells rapidly divide to form Palma cells , produce the right antibody
