Defence mechanisms & immunology Flashcards
Pathway of the lymph system (7 steps)
Lymphatic capillary Afferent lymphatic vessel Lymph node Efferent lymphatic vessel Lymphatic trunk Collecting duct Subclavian
3 main organs of the lymphatic system
Lymph nodes
Spleen
Thymus
7 non specific barriers against infection
Species resistance Mechanical barriers Chemical barriers Natural killer cells Inflammation Phagocytosis Fever
2nd line of defence
Phagocytosis
7 phases of phagocytosis
1)Chemotaxis and phagocyte sticking to microbe
2)Ingestion of microbe by
Phagocyte
3)Engulfing microbe is s phagosome (endocytosis)
4)Fusion of phagosome with lysosomes to form phagolysosome
5)Lysozyme enzymes in lysosomes break down and digest microbe
6)Formation of residual body containing indigestible material
7)Discharge of waste materials
7 steps of inflammation
1) Bacteria and other pathogens enter wound
2) platelets release blood clotting proteins at site
3) mast cells mediate vasodilation and vascular constriction.
4) neutrophils secrete factors that kill and degrade pathogens
5) neutrophils and macrophages remove pathogens by phagocytosis
6) Macrophages secrete cytokine hormones that attract immune system cells to site
7) inflammatory response continues until foreign material eliminated and wound repaired
Chemotaxis
Movement of phagocyte towards microbe in response to chemicals
Phagosome
A vacuole in the phagocyte cell membrane containing a microbe
Endocytosis
Engulfing a foreign body into the cell membrane to form a vacuole
A phagocyte that has fused with a lysosome
Phagolysosome
Neutrophil
A type of immune cell (white blood cell)
First line of defence
Skin
Third line of defence
Cellular immune response
Humoral immune response
Specific immunity
Cellular immune response
Humoral immune response
B cell and T cell origin
Red bone marrow
Where are B and T cells primarily found
Lymphatic tissues
T cell function
Cellular immune response
T cells interact with antigens to destroy them
Helper T cells
Cytotoxic T cells
B cell function
Humoral response
B cells interact indirectly with antigen
They produce antibodies that destroy antigen
How are Antibodies specific to antigens
Active site on antibodies are specific in shape to antigen
What activates a B cell?
Cytokines released by T cells + Binding with an antigen
What happens when a helper T cell contacts a displayed antigen?
It multiplies by division and releases cytokines to activate B cells and other chemicals to activate cytotoxic T Cells
What activates cytotoxic T cells?
T helper cells release chemicals to activate cytotoxic T cells
What happens when cytotoxic T cells are activated?
They divide into memory cells and cytotoxic T cells
What happens to activated B cells?
They multiply into other B cells which produce monoclonal antibodies
What happens when antibodies combine with antigens?
Complement proteins are activated
What 5 ways do antigens destroy pathogens?
Oponisation Chemotaxis Lysis Agglutination Neutralisation
Oponisation
Enhancing phagocytosis of antigens
How to antibodies cause chemotaxis towards pathogens?
They attract macrophages and neutrophils
Lysis
Rupturing cell membranes (foreign pathogenic cells)
Agglutination
Antigens causing pathogens to clump (destroy more at once)
Neutralisation
Altering the molecular structure of viruses
Primary response
Symptoms
Takes longer to destroy pathogen
Memory B cells and memory T cells produced
Secondary response
Memory cells existing
Pathogen destroyed sooner
No symptoms
(Second exposure to same pathogen)
Natural active immunity
Acquired naturally by exposure to live pathogens
Immune response causes antibodies to be produced naturally
Long term affect
Artificially acquired active immunity
Exposure to vaccine
(Artificial pathogen -dead/weak)
Antibodies produced (active) without symptoms (long term immunity as B memory cells remain in blood and remember how to create antibodies, T cells recognise antigen)
Natural passive immunity
Antibodies passed to fetus from mother in breast milk (antibodies given directly=passive)
Provides short term immunity
Artificial passive immunity
Injection of antibodies
Short term immunity
What 4 ways does the placenta function as an immunological barrier
Secreted chemicals that avoid detection by the host
Contains lymphocyte suppressor cells that inhibit maternal TC cells
Placental cells do not express MHC I complexed (prevents destruction to TC cells)
Creates a syncytium (fewer intercellular sites for access of maternal cells)
When is the only case that IgG would target fetal cells?
If they were found in maternal circulation
What causes the fetus to have a passive immune system?
Placenta allows IgG cells to cross to fetus
4 signs of inflammatory response
Redness, pain, swelling, heat
Oedema
Swelling
6 stages of inflammatory response
1) damaged tissue
2) histamine and kinins
3) vasodilation
4) oedema (swelling)
5) pain receptors activated
6) WBCs activated
First and second lines of defence are
Non specific/innate
Third line of defence is described as
Specific or adaptive
Humoral response involves
Pathogens in bodily fluids
Cellular response involves
Infected cells
T lymphocyte cells originate in
And move to. To mature
Bone marrow
Thymus gland
What two type of cells do T cells divide into
T helper cells
Memory T cells
