Immune system Flashcards
Name some innate defenses
-surface barriers(skin, mucos membranes)
-internal defences (phagocytes,inflammation,antimicrobial proteins)
What do innate/ non specific resistance defences respond to?
a range of pathogens or foreign substances
Name some adaptive defenses/specific resistance
-humoral immunity-B cells
-cellular immunity-T cells
What do adaptive defenses respond to?
a particular pathogen or foreign substance
Name key barriers in the first line of defence
-mechanical (skin,mucous)
-chemical (stomach acid, lysozymes)
Name some key components involved in the second line of defence
-antimicrobial proteins
-natural killer cells
-phagocytes
-inflammation
-fever
Name some antimicrobial proteins involved in the second line of defence
-stomach inteferon
-complement(enhances the immune system
-transferrins(inhibit certain bacterial growth)
What do natural killer cells do?
destroy cells by perforating the plasma membrane making them leaky
Describe the role of a fever in the second line of defence
-the body’s thermostat in the hypothalamus is reset to a higher level
-increased temp enhances interferon, inhibits some microbial growth and speeds up repair
What is the adaptive defence characterised by?
specificity- each invading agent is recognised as being different from each other
memory- a second response is faster and greater than the first
What is specific resistance carried out by?
lymphocytes that originate in the bone marrow
describe immunocompetence and self tolerance
once mature lymphocytes acquire specific antigen receptors that allow them to recognise specific invading agent
Describe the antibody mediated/ humoral response
-B cells develop in red bone marrow
-once stimulated by an antigen, B cells clone and become plasma cells
-plasma cells produce antibodies also known as immunoglobulins
Describe the production of antibodies
- specifc antigen is identified by a specific B lymphocyte
-B cells form a clone and become plasma cells
-plasma cells secrete antibodies
What are the five classes of antibodies?
IgG
IgA
IgM
IgE
IgD
What is the IgG antibody?
main antibody and able to cross placenta
What is the IgA antibody?
secretory antibody
What is the IgM antibody?
released into plasma, indicates current infection
What is the IgE antibody?
associated with allergies and parasitic infections
What is the IgD antibody?
attached to B cell and acts as an antigen receptor
what are antibody mediated responses directed against?
extracellular pathogens such as bacteria
Describe the cell mediated immune response
T cells leave bone marrow and migrate to the thymus to complete their development
-T cells become killer T cells that directly attack invading antigen
-Or they become helper T cells that help both antibody-mediated and cell mediated responses
What are cell mediated immune response directed against?
intracellular pathogens such as viruses, cancer cells and tissue transplants
Describe the role of the memory cells produced by B and T cells
-memory of previous invading antigens allow for the second or subsequent response to be much quicker and greater
Whats the difference between the primary and secondary response?
primary- slow and innefective, signs and symptoms of the disease are seen
secondary-faster and greater, signs and symptoms of the disease are not seen
describe the two types of active humoral immunity
naturally acquired-infection contact with pathogen
artifically acquired-vaccine dead or attenuated pathogens
Describe two types of passive humoral immunity
naturally acquired-antibodies pass from mother to fetus via placenta
artifically acquired-injection of immune serum (gamma globulin)
What is the autoimmune response?
the body does not recognise its own tissues because it recognises them as self.
What is immunological tolerance?
the body tolerates its own molecules
Name some examples of autoimmune diseases
MS-destroys the mylein of the nervous system
Rheumatoid arthiritis-destroys the cartilage of joints
Type 1 diabetes-destroys insulin producing pancreas cells
glomerulonephritis-destroys nephrons of the kidneys
Myasthenia gravis-impairs communication between nerves and skeletal muscles by destroying receptor sites
Describe the first exposure to an allergen
-allergen invades body
-plasma cells produce large amounts of class IgE antibodies against allergen
-IgE antibodies attach to mast cells in body tissues and to circulating basophils
Describe the subsequent exposure response to an allergen
-more of the same antigen invades body
-antigen combines with IgE attached to mast cells and basophils which trigger degranulation and release of histamines and other chemicals
-histamine causes blood vesseld to dilate, promoting oedema, stimulates secretion of large amounts of mucus, causes smooth muscle to contract
What is an anaphylatic reaction?
involves the breakdown of mast cells and basophils and may result in anaphylatic shock
What is a cytotoxic reaction?
typical of incompatible blood transfusions resulting in destruction of cells
What is an immune complex reaction?
the destruction of tissue such as rheumatoid arthirits, glomurelonephritis
Describe delayed hypersensitivity reactions
appear 12-72 hours after exposure such as mantoux skin test for TB
