Non-Specific Animal Defences Against Disease Flashcards
(14 cards)
What is the immune system?
The immune system is a group of cells, tissues, organs and mechanisms that defend an organism against pathogens (disease-causing organisms) and other foreign substances.
What are some examples of Physical barriers within the body?
Skin
Skin Flora
Mucous Membrane
Lysozyme
What is sebum?
The skin produces sebum, an oily substance that inhibits pathogen growth.
What is Skin flora?
Skin Flora – the skin naturally has a large population of natural health bacteria. These outcompete pathogens for surface space.
Where are lysosomes found?
In tears, urine and in stomach acid
What are the stages within blood clotting and wound repair?
Platelet’s rush to the site they release two substances: Thromboplastin and
Serotonin
Serotonin causes muscles to contract around the wound reducing the gap
The clot dries out forming a hard scab keeping pathogens from entering
Epidemical (skin) cells grow beneath the sab, collagen fibers reinforce the skin cells
What is the inflamatory response?
Inflammation is the swelling of skin immediately around the rupture. This is characterized by pain, heat and redness Mast cells are activated when skin is ruptured they release histamines and cytokines
What is a histamine?
These make blood vessels dilate, causing localised heat and redness. High temperature prevent pathogen reproducing
Histamines also increase the permeability of the cell, causing more tissue fluid to escape causing swelling and the pain
What are cytokines
Cytokines attract white blood cells to deal with any pathogens
What is the normal body temperature of a human?
Normal core body temperature is 37 degrees
What are the steps for clotting?
Damaged tissue results in platelets being activated, these release thromboplastin.
This catalyzes the reaction with prothrombin and calcium ions to form thrombin
Thrombin catalyses the formation of fibrin using fibrinogen, which causes a clot.
What are the stages of Phagocytosis
Pathogens produce chemicals and other toxins
that attract phagocytes (white blood cells)
Phagocytes recognise foreign antigens on
pathogens as not being of the organisms
The phagocyte engulfs the pathogen putting it
into a specialised vacuole called a phagosome
The phagosomes combined with a lysosomes,
which contain powerful digestive enzymes, to
form a phagolysosome
Enzymes in the phagolysosome break down the pathogens
The broken down pathogen is moved out of the phagocyte by exocytosis
What are macrophages?
Macrophages are specialised phagosomes which take longer to break pathogens down
than normal phagocytosis
What are Opsonins
These are produced by phagocytes and
‘tag’ pathogens making them more visible to other phagocytes
