IMMUNITY Flashcards
What are antigens
Antigens are molecules, or part of a molecule that elicit an immune response
Difference between self and non self antigens
A molecule on an organism’s cells that the immune system recognizes as healthy self cell, preventing an immune response.——self antigen is a type ofmhc marker epexressed on humansand other verterbrates
whereas,
A molecule from outside the body that is recognized by the immune system and initiates an immune response.
compAREMHC class I and MHC II markers
MHC class I
Found on all nucleated cells in the body
Not found on RBC due to lack of nucleus
MHC class II
on specialised antigen-presenting cells; interact with T helper cells during antigen presentation by presenting antigen presenting cells on T helper cells to help initiate an immune response against pathogens.
since Red blood cells do not contain MHC markers, what do they use to mark themselfs as ‘self’
Red blood cells contain glycoproteins to label them ‘self’
rbs have no nucleus so no mhc marker
autoimmune disease
Failure to recognise self from non-self leads immune system atttack self cells resylts jjn to an autoimmune disease. Examples include multiple sclerosis, Type 1 Diabetes, rheumatoid arthritis.
allergic reaction
Over reaction to an otherwise harmless non-self antigen is known as an allergic reaction. Common allergens are eggs, seafood, peanuts.
what are pathogens and what are the 2 cateorgie sof pathogens and provide examples of these
Pathogens are foreign agents that cause disease
Can be either
Cellular: have a cellular structure and are living. Examples include bacteria, parasites, fungi.
Non-cellular: do not have a cellular structure and are typically non- living. Examples include viruses, prions.
Bacteria, what type of path9ven are they, how do they cause cellular death, some are good bc, how are they fought/treated
Cellular pathogens
Unicellular prokaryotes reproduce via binary fission
Releases toxins and enzymes causing cells to lyse death
Some are beneficial in the GI tract.
Treated with antibiotics
Fungi
Cellular pathogen
Eukaryotic cells reproduce via spore formation (sexual or asexual reproduction)
Contain cell wall but no chloroplasts
Include yeast and moulds
Thrive in moist conditions
Protozoa
Cellular pathogen
Single celled eukaryotes
Requires a host to feed on and reproduce
Viruses
Non-cellular pathogens Invade cells and replicate using host cells.
Made up of genetic material (DNA or RNA) inside a protein coat (capsid)
Requires a host cell to replicate
Antigens can mutate making it difficult for our immune system to respond quickly.
Prions
Non-cellular pathogen
Made up of protein only (no genetic material)
Causes other proteins to misfold
Can infect the brains of some mammals (e.g. mad cow disease)
Types of barriers
Physical: Barriers that block or hinder pathogens from entering
Chemical: Barriers that work by producing chemical substances to inhibit the growth/ destroy pathogens
Microbiological: non-pathogenic bacteria (normal flora) to prevent growth of other bacteria competes with bad bacteria addxsmth a good a good uis
Barriers in plants
Physical – including thick bark to prevent entry of pathogens, waxy cuticles on leaves, thorns, stomata closing.
Chemical – include tannins from tea which a toxic to insects, phenols to repel microorganisms, caffeine which is toxic to insects and fungi, other enzymes that disrupt cell membranes of fungi.
Barriers in animals (physical)
Physical barriers include
Intact skin
Mucous secretions
Hairs in the respiratory tract
Cilia
Mucous Secretions and Cilia: Sweep pathogens away from airways and into the throat to be destroyed by the gastrointestinal tract.
Intact Skin: Forms a continuous layer that prevents pathogen entry.
Body Hair: Prevents foreign particles from directly contacting the skin.
Barriers in animals (chemical
Chemical barriers include
Lysozyme enzymes in tears and saliva to destroy bacteria
Acidic sweat
Earwax containing antibacterial compounds
Antibacterial proteins in semen
low pH in vagina
Stomach acid
Sweat: Lowers the pH of the body, contains toxic lipids, and washes microbes away.
hydrchlori acid: Break down complex carbohydrates, destroying potential pathogens.
Ear Wax: Hydrophobic nature, acidic pH, and antimicrobial properties protect the ear canal from infections.
Barriers in animals (microbiological)
Microbiological barriers include
Bacteria on the skin
Bacteria in the GI tract
Bacteria in the vagina
All prevent the grown or colonisation of pathogenic microorganisms as they compete for space
compare the first, second and third line of defence.
pathogen
A foreign substance that causes a disease.
wjat are MHC makrers
MHC markers are proteins found on the surface of self-cells that allow the immune system to differentiate between self-cells and non-self cells.
What are phagocytes and types of phagocyte sand explain
Specialised leukocytes responsible for endocytosis and the destruction of pathogens, foreign material, and cell debris
types of pahgocytes
process of phagocytutpsisi
When a pathogen is recognised as non-self, it is engulfed by a phagocyte via endocytosis
The pathogen is enclosed in a vesicle inside the cell and fuses with a lysosome. Enzymes in the lysosome digest the bacteria
Fragments are released as waste via exocytosis OR if the phagocyte is an antigen presenting cell, fragments are displayed on the MHC class II marker to present to the adaptive immune system
what are the antigen presetnign cells
Antigen-presenting cells (APCs) are specialized immune cells that capture, process, and present antigens on MHC (Major Histocompatibility Complex) molecules on their surface to T helper cells, activates T helper cells, helping to initiate the adaptive immune response