Defence Against Disease Flashcards
Innate non specific primary
Primary defence, keeping pathogens out
Skin, cilia , blood clotting , ear wax, stomach acid
Innate non specific secondary
Secondary defence, getting rid of pathogens
Phagocytes
Adaptive specific immune response
Targeting pathogens. ( immunity)
Lymphocytes
Skin adaptation
Covers the body and prevents the entry of pathogens.
Has a skin flora of healthy microorganisms which deter pathogens as they will have to compete for space.
Skin also produces sebum, which is an oily substances which inhibits the growth of pathogens
Mucous membranes
Many of the bodies tracts, such as airway passages are lined with mucous membranes that secrete sticky mucus trapping bacteria.
Mucus contains lysosomes which destroy bacterial and fungal cell walls
Mucus also contains phagocytes which remove pathogens
Where are Lysosomes found
Found in tears, urine and in the stomach acid.
Blood clotting and wound repair
When platelets come into contact with collagen in skin or the wall of damage blood vessels, they adhere and begin secreting several substances.
Thromboplastin- an enzyme that triggers a chain of reactions causing the blood to clot.
Serotonin- which makes the smooth muscle in blood vessels contract reducing the blood supply to the area
Inflammatory response
Localised response.
Mast cells are activated in damaged tissue and released chemicals called histamines and cytokines.
Histamines- make the blood vessels dilate causing localised heat and redness.
This increased temperature prevents pathogens reproducing.
Histamines make blood vessel walls more leaky so blood plasma is forced out, tissue fluid, causing swelling and pain
Cytokines- attract white blood cells to the site, they dispose of pathogens by phagocytosis.
Fevers
When a pathogen invades your body, cytokines stimulates your hypothalamus to reset the thermostat and your temperature goes up
- most pathogens reproduce best at 37 degrees or below
- the specific immune system works faster as higher temperatures
What do phagocytes do
Phagocytes are white blood cells that engulf and destroy pathogens.
Phagocytes build up at the site of an infection and attack pathogens. Pus consists of dead neutrophils and pathogens
Stages of phagocytosis
Pathogens produce chemicals which attract phagocytes
Phagocytes recognise the cell as either self or non self due to the proteins on the pathogen
Phagocytes engulf the pathogen and encloses it in a vacuole called a phagosome
The phagosome combines with a lysosome to form a phagolysosome
Enzymes from the lushness digest and destroy the pathogen
Counting blood cells
Thin smears of blood are stained so the nuclei of lymphocytes can be seen.
Identifying the different types of lymphocytes in a blood smear indicates a non-specific or specific immune response is taking place
Helpful chemicals - cytokines
Phagocytes that have engulfed a pathogen produce chemicals called cytokines.
Cytokines act as cell cell signalling molecules, informing other phagocytes that cell in under attack and stimulating them to move to the site of infection.
Cytokines can also increase body temperature and stimulate the specific immune system
Helpful chemicals - opsonins
Chemicals that bind to pathogens and “tag” them so they can be more easily recognised by phagocytes.
Phagocytes have receptors on their cell membrane the bund to common opsonins, and the phagocyte then engulfs the pathogen.
Antibodies such as immunoglobulin (G) and immunoglobulin (M) have the strongest effect
Stages of phagocytosis
The phagocytes recognise the chemicals realised by the pathogen and are attracted to them.
The phagocyte recognises the pathogen as “non-self” due to its antigens
The phagocyte engulf the pathogen forming a vacuole around the pathogen called a phagosome
The phagosome then fuses with a lysosome to form a phagolysosome
Enzymes from the lysosome digest the pathogen
Useful products from digestion are used up by the cell, the waste products are removed via exocytosis
