Non-Specific Defences Against Diseases Flashcards
What is the Immune System?
A group of cells,tissues,organs and mechanisms that defend an organism against pathogens and other foreign substances.
What is an Immune Response?
Complex series of specific an non-specific processes involving a range off the cells and chemicals.
What will happen if the body successfully fights an infection?
It will respond more quickly and effectively if the same pathogen is re-encountered.
What are the physical barriers?
-Skin
-Skin Flora
-Mucous Membranes
-Lysozyme
How does the skin act as a physical barrier?
Acts as a barrier all around the body to prevent the entry of bacteria.
What does the skin produce?
Sebum, an oily substance that inhibits pathogen growth.
How does Skin Flora act as a Physical Barrier?
The skin has a naturally has a large population of natural health bacteria. These outcompete pathogens for surface space.
How does Mucous Membranes act as a Physical Barrier?
Gas exchange surfaces have a layer of mucus that trap pathogens.
What does this mucus contain?
The enzymes which destroy bacteria.
How do lysozyme’s work as a Physical Barrier?
In tears, urine and in stomach acid also destroys pathogens.
What happens if the skin is ruptured?
Pathogens may enter the blood.
How many stages in blood clotting?
3
What is the first stage in blood clotting?
Platelets rush to the site and they release 2 substances.
What 2 substances do they release?
Thromboplastin and Serotonin
What does serotonin cause?
Muscles to contract around reducing the gap
What is the second stage in blood clotting?
The clot dries out forming a hard scab keeping pathogen from entering.
What is the third stage in blood clotting?
Epidemical (skin) cells grow beneath the scab, collage fibres reinforce the skin cells.
What is inflammation?
The swelling of skin immediately around the rupture.
What is inflammation characterised by?
Pain, heat and redness
When are mast cells activated?
When skin is ruptured they release histamines and cytokines.
What are histamines?
Make blood vessels dilate, causing localised heat and redness.
What does high temperature prevent?
Pathogens from reproducing.
What do histamines also do?
Increase the permeability of the cell membrane, causing more tissue fluid to escape causing swelling and the pain.
What do cytokines attract?
White Blood Cells to deal with any pathogens.
What is the normal core body temperature?
37 degrees
What is body temperature controlled by?
Hypothalamus in the brain
What causes the hypothalamus to reset?
During infection, the large presence of white blood cells cause this which increases temperature.
Why does this happen?
As pathogens cannot reproduce as quickly at temperatures above 37 degrees and the specific immune system can work faster.
What does the non-specific immune response target?
Quickly targets a wide range of pathogens and foreign substances.
What is another name for non-specific immune response?
Innate immune response
Give some examples which are parts of this immune response?
Phagocytosis, inflammation and the anti microbial proteins, lysozyme and interferons.
What is Lysozyme?
An enzyme that disrupts the cells of gram-positive bacteria by digesting the Peptidoglycan.
Where is lysozyme found?
In human tears, saliva and lysosomes
What are interferons?
Proteins produced by virus-infected body cels in response to the virus.
What do Interferons trigger?
The production of a second protein that inhibits viral replication by binding to mRNA code by the virus.
What is the first stage of Phagocytosis?
Pathogens produce chemicals and other toxins that attract phagocytes. (WBC)
What is the second stage of Phagocytosis?
Phagocytes recognise the foreign antigens on pathogens as not being of the organism.
What is the third stage of Phagocytosis?
The phagocyte engulfs the pathogen putting it into a specialised vacuole called a phagosome.
What is the fourth stage of Phagocytosis?
The phagosomes combined with a lysosomes which contain powerful digestive enzymes, to form a phagolysosome.
What is the fifth stage of Phagocytosis?
Enzymes in the phagolysosomes break down the pathogens.
What is the sixth stage of Phagocytosis?
The broken down pathogen is moved out the the phagocyte by exocytosis.
What are Macrophages?
Specialised phagosomes
What is different about macrophages to phagosomes?
Macrophages take longer to break pathogens down than normal phagocytosis.
What happens once macrophages are broken down?
The foreign antigens of the pathogen bind with the antigens of the macrophage to form MHC.
What is then displayed?
The antigens on the macrophages plasma membrane to form a APC.
What does APC stand for?
Antigen-presenting cell
What does MHC stand for?
Major histocompatibility complex
What are the 2 helpful chemicals?
-Cytokines
-Opsonins
What are cytokines?
Phagocytes that have engulfed a pathogen produce chemicals called cytokines.
What do cytokines act as? And how do they perform this role?
Cell signalling molecules, informing other phagocytes that the body is under attack which stimulates them to move to the site of infection or inflammation.
What do cytokines also do?
Increase body temperature and stimulate the specific immune system.
What are opsinins?
Chemicals which bind to pathogens and ‘tag’ them so they can be more easily recognised by phagocytes.
What do phagocytes have which allow opsonins to carry this out?
Receptors on cell membranes which bind to common opsonins and the phagocyte then engulfs the pathogen.
Which type of opsonins have the strongest effect?
Number of different types by antibodies have the strongest effect.
