Chapter 6 - Detecting and Responding to Invaders Flashcards
First fine of defence mechanisms
- Keratinised, Intact skin
- Cilia/nasal hairs: filters air and sweeps out pathogens trapped in mucas
- Digestive system: lysosomes in saliva and enzymes and strong enzymes create non-preferable environment.
- Respiratory: Mucas straps pathogens
- Urinary Tract: Flush out pathogens
Second line of defense
Non- Specific defence
- Macrophages, Neutrophils, macrophages, Eosinophils, basophils
- Complement system
- Natural Killer Cells
- Inflammation and fever
- Interferons
Third line of defense
Specific response
B-cells, T-cells
Phagocyte definition &; Examples
- White blood cells that engulf and digest foreign particles.
- EG.) Neutrophils, Macrophages, Monocytes (macrophages in the blood)
Neutrophil
Phagocyte, Not antigen presenting
- It granules contain enzymes and chemical which break down foreign material
Moncytes &; Macrophage
Monocytes in the blood respond to cytokinins, migrate to inflamed site where they squeeze out of blood vessels to become macrophages.
- Macrophages engulf pathogens
- Are antigen presenting
MHC1 & MHC2
MHC proteins act as signposts that display antigen on the hosts cells surface.
MHC1 on all cells
MHC2 Only found on antigen presenting cells
Antigen presenting cells definition and 3 examples
Cells that envelop a pathogen and display antigen fragments on their MHC2 markers.
B plasma cells
Found in Lymph nodes and in blood stream
Exist in millions of different types with unique membrane bound antibodies on surface which detect microbes with antigens which bind to them.
The steps and actions of phagocytes
- ) Detection: Phagocytes detects microbes by chemicals they give off
- ) Ingestion: Microbe is enveloped through endocytosis.
- ) Digestion: Phagosome (vesicle containing thee microbe) fuses with lymosome which contains enzymes which break down the microbe into its chemical constituents. (Enzymes break down microbe)
- ) DIshcharge: Antigens are displayed on MHC2 markers (macrophages) and the rest of the digested contents are discharged
Humoral response
- Plasma cells unique antibodies on its surface bind to complementary non-self antigen.
- Helper T cell (having already met the antigen) activates this B- Cell by producing interlukin, stimulating it to begin “clonal expansion” and divide into B plasma and B memory cells.
- These B plasma cells produce antibodies which help combat the pathogen,
Dendritic cells
Antigen presenting cells that attract antigens and present them to T-Helper cells
epitope
Processed antigen fragment
Granulyte properties and examples
Properties: Granular cytoplasms, multi-lobed nucleus
Eg.) Neutrophil, Eosinophil, Basophils, NKC
Neutrophil Vs Macrophage
Both engulf foreign particles and micro-organisms
Neutrophils arrive at scene faster and have a shorter lifespan than macrophages.
Neutrophils are not antigen presenting, macrophages are
Eosinphil role:
secretes enzymes which break down cell walls of pathogens
Basophil role:
Secrete histamine in case of infection causing inflamation
Mast Cells;
Types of Basophil which produce histamines and is involved in allergic reactions
Macrophges Vs Monocytes
Monocytes turn to macrophages when they leave the blood stream.
They develop in the bone marrow and engulf foreign particles
Dendrite cells:
Antigen presenting cell with long tentacle like arms which grab foreign particles
Leukocytes Vs Lymphocytes
Leukocytes = general term for WBC Lymphocyte = specific WBC produced in lymph and which exist in blood and lymph
B Cell: What is it; General role: subspecies: matures where
Lymphocyte which produces antibodies specific to a specific antigen. Divides into plasma and memory cells.
Matures in bone marrow
T Cell:
What is it;
matures where:
Lymphocyte that matures in the thymus and divides into various Helper, cytotoxic and repressor T cells which respond to specific antigen.
Lymphocytes definition and two (main) types
specific WBC produced in lymph and which exist in blood and lymph
- T Cells
- B Cells
Cellular Response
Macrophage phagocytise and present antigen of pathogen to Helper T-cell.
Helper T-Cell activates Cytotoxic T cell and stimulates proliferation.
Cytotoxic T Cell triggers apoptosis in infected cells
Humoral response
Macrophage phagocytise and present antigen of pathogen to Helper T-cell.
Helper T-Cell activates B-cell stimulating it to divide (clonally expand) into memory and plasma cells.
Plasma B - Cells create antibodies which act against the pathogen.
Role of cytotoxic T cells
Specific cells which contain chemicals which kill foreign and infected cells which display a specific antigen on their MHC 1 marker.
Role Of B - Plasma Cells
Cells which clonally divide in response to a pathogen and produce specifc antibodies which act against pathogen.
Helper T Cells
Cells which activate or aid other cells in the immune system
Supressor T Cells
Cells which turn off or suppress activity of other cells once threat has passed
Antibody actions
Agglutination: Binds multiple pathogens together simultaneously.
Marks pathogen or toxin for macrophages
Neutralisation: Antibodies surround to and bind to pathogen or toxin disallowing it to interact chemically with the body
Complement system:
How it works:
System composing of various proteins which circulate freely in the blood and congregate and form a protein attack complex on foreign cells. Causes a pore to form and the cell to die
Interferon
Signalling chemicals released by cell infected by pathogen, warning neighbouring cells of the presence of a pathogen and causing them to heighten anti-viral defence. This is done through the production of enzymes which reduce the capacity for virus to inject DNA and reproduce.
cytokines
Chemicals released which allow for a means of communication by cells of the immune system.
Role of Lymph system
Assists in defence by housing and transporting leucocytes and lymphocytes. Is connected to the bloodstream.
Primary Lymph System and Role;
Consists of bone marrow and and the thymus gland.
Involved in the development of lymphocytes.
Bone marrow: all blood sells from bone marrow stem cells. place of B- Cell maturation
Thymus: Place of T - Cell maturation
Role of lymph nodes
Surveillance and filtering of bodily fluid
What is the adaptive response
Specific response of the third line of defence involving B and t cells
Inflammation:
What is it and cause
inflammatory response is a localised non-specifc response to infection. Triggered by infected and injured cells which produce histamine.
Role of histamine
Cause vasodilation and increase blood flow
Increase permeability of capillaries allowing WBC’s to migrate to extracellular fluid and attack bacteria.
Symptoms of inflammation:
Red, raised, warm, sore
Fever:
What is it and steps:
Rise in body temperature in response to a pathogen due to the resetting of the thermostat.
- ) macrophage phagocytises pathogen and releases cytokine.
- ) Cytokine circulates and reaches brain where it stimulates the hippocampus to produce prosteglandins which reset the bodies thermostat to higher temp. This causes shivering and vasoconstriction to warm the body up.
- ) As long as cytokines are released by macrophage thermostat remains raised.
- ) Threat passes, cytokine production halts and thermostat is lowered to normal. Body will sweat and vasodilate to cool down
Active immunity
Occurs when immune system responds to a foreign antigen and produces specialised B and T lymphocytes.
Passive Immunity
Occurs when antibodies are transferred from a secondary source.
Natural & Artificial acquired immunity
Natural = Mother antibodies transferred to child's during pregnancy and breast feeding. Artificial = Antibodies injected artificially from secondary production source other than self.
Natural and Artificial Active Immunity
Natural: Responds to live disease causing pathogen
Artificial: Responds to attenuated or manipulated pathogen in the form of a vaccine.
Primary Vs Secondary response to infection
Primary; Slow response as body does not posses enough specialised B and T Cells to combat pathogen.
Secondary: Faster response (steeper gradient), more total antibodies, and lymphocytes produced.
What is auto-immune disease?
Occurs when the normal self recognition system within the immune system fails and certain cell tissue types are no longer recognised as self.
Steps of Allergic reaction.
- ) B-lymphocyte encounters allergen, differentiates into B plasma cells and produces antibodies.
- ) Antibodies (Ig E) bind to specific receptors on the surface of the mast cell
- ) When allergen arrives a second time the allergen binds to the antibodies which create a crosslink between allergen and mast cell.
- ) Mast cell degranulates and releases histamines into the blood which trigger inflammation. More crosslinks = greater response
Anaphylactic reaction
Too much histamine is released.
Histamine circulates in blood and cause vessels to vasodilate and leak fluid into tissue causing inflammation around the body and decreased blood pressure.
Can result in circulatory collapse
Naive T & B Cells
B and T cells, before they have been activated by a helper T cell
Purpose of apoptosis
Kill cells which are not functioning properly
Kill cells which are no longer required
