immune system Flashcards
what are the components of the lymphatic system?
- lymphatic system
- lymphoid organs and tissues
- WBC
- cytokines
what are the components of the lymphatic system?
- lymph
- lymph nodes
- lymphatic capillaries and vessels
what are possible pathogens?
- viruses
- fungi
- parasitic worms
- bacteria and their toxic products
what is the function of the lymphatic system?
- circulatory body fluids
- removes foreign materials from body fluids
- transports WBC
what does lymphatic capillaries contain?
flaplike mini valves that permit the entry of ISF, WBC, and foreign materials into lymphatic capillaries
what is lymph?
white milky protein-containing fluid, excess ISF
what do lymphatic vessels do?
carries lymph from peripheral tissues back to the blood (venous circulation)
what does the circulation of lymph via the lymphatic vessels do?
- regulates ISF volume
- maintains blood volume and bp
- transports WBC and foreign materials to lymph nodes
what occurs if lymphatic drainage is blocked?
lymphoedema
where are lymph nodes located?
along lymphatic vessels
what do the lymph nodes do?
trap foreign materials
what do WBC’s in the lymph nodes do?
- directly destroy foreign materials
- activate an immune response
what do primary lymphoid organs contain?
stem cells that differentiate into various WBC’s of the lymphoid system
what are secondary lymphoid organs and tissues the site of?
where foreign materials become trapped and destroyed or an immune response is generated
what are examples of secondary lymphoid organs and tissues?
-lymph nodes, spleen, appendix, tonsils
what are the different types of WBCs?
- neutrophils
- macrophages
- mast cells
- basophils
- eosinophils
- lymphocytes (natural killer cells, t and b cells)
where are WBCs found?
- blood
- lymph
- lymphoid organs and tissues
what are cytokines produced and secreted by?
WBC
what do cytokines do?
the chemical messengers that recruit and/or activate WBC
what are the two main immune defenses?
innante (non-specific) and adaptive (specific) defences
what makes up the first line of defence?
surface barriers
what makes up the second line of defence?
internal defences
what makes up the third line of defence?
immune response
are innate defences present at birth?
yes
what do innate defences provide?
immediate protection against any type of foreign material
what do innate defences aim to do?
prevent foreign materials from entering and spreading throughout the body
what are two types of barriers that make up surface barriers of the first line of defence?
physical and chemical barriers
what is the aim of the first line of defence?
prevent entry
what are the physical barriers of the first line of defence?
intact skin and mucous membranes
what are the accessory structures of the physical barriers of the first line of defence?
hair and cilia
what are the chemical barriers of the first line of defence?
- sweat, saliva, and tears
- sebum
- mucus
- gastric juices
how do tears, saliva and sweat protect against foreign materials?
cleanse body surfaces and contain lysozyme which destroys bacteria
how does sebum protect against foreign materials?
is an acidic skin secretion that inhibits pathogen growth and toxic to some bacteria
how does mucus protect against foreign materials?
traps
what does the second line of defence prevent?
foreign materials from spreading
what does the second line of defences involve?
- macrophages and neutrophils
- natural killer cells
- interferons
- complement
- pyrogens
- inflammatory response
what do macrophages and neutrophils do?
phagocytose and destroy all types of foreign materials via lysosomal enzymes
what types of cells do natural killer cells destroy?
virus-infected and cancerous cells
how do natural killer cells destroy?
recognise, adhere to, and destroy target cells via the release of perforins and granzymes
what do perforins create?
pores in target membrane allowing entry of granzymes
what do granzymes induce?
apoptosis
what do interferons inhibit?
viral replication
what do interferons activate?
macrophages and natural killer cells to destroy virus-infected cells and cancerous cells
what do complement proteins do?
- recruit macrophages and neutrophils to the site of invasion
- enhance phagocytosis by opsonisation
- directly destroy cellular targets by forming membrane attack complex= cell lysis
- enhance inflammatory response
what are pyrogens?
a group of proteins which reset the body’s hypothalamic thermostat and increase body temp
how can mild or moderate fevers be beneficial?
inhibit growth of some bacteria and viruses and increase cell metabolism which accelerates immune defences
what is an antigen?
a molecule capable of inducing an immune response
what do activated t and b cells mount?
an immune response toward antigen
what is immunocompetence?
the ability to recognise and bind one specific antigen
what do T cells bind to?
membrane-bound t cell receptor
what do B cells bind to?
membrane-bound antibody receptor
what is self-tolerance?
ability to recognise self-antigens from non-self
where do B cells mature?
bone marrow
where do T cells mature?
thymus
what is immunological memory?
the ability to remember antigens
what is a cellular response mediated by?
cytotoxic T cells
what is humoral immune response mediated by?
B cells
what activates the cellular and humoral response?
helper t cell
what do activated helper t cells proliferate to produce antigen-specific?
effector and memory helper t cells
what do effector Helper T cells secrete and what does this activate?
cytokines that activate cytotoxic T cells and B cells
what do activated cytotoxic T cells proliferate to produce?
antigen-specific effector and memory cytotoxic T cells
what do effector cytotoxic T cells do?
roam the body and destroy cellular antigens present by releasing perforins and granzymes
what do activated B cells proliferate and differentiate to produce?
plasma and memory cells
what do plasma cells secrete?
Ag-specific antibodies
what do antibodies do?
circulate in body fluids and bind to extracellular antigens to form antigen-antibody complexes
what do antigen-antibody complexes do?
inactivated tag antigens for destruction by phagocytes or complement
what are the five major classes of antibodies?
IgM, IgG, IgA, IgD and IgE
what is the primary immune response?
first antigen exposure produces a small, slow, short-lived response that doesn’t protect from illness
what antibody class is produced first then second?
IgM then IgG
what is the secondary immune response?
subsequent antigen encounters produces rapid and long-lasting response that protects from illness
what is a vaccine?
exposure of an individual to an antigen, inactive or attenuated (weak), this provides the first antigen encounter priming body for secondary response
how does an immunodeficiency disease occur?
when the body’s immune defences are compromised or absent and unable to mount an effective response
when does an autoimmune disease occur?
when the body’s immune defences target normal cells and tissues
when does hypersensitivity occur?
when the body’s immune defences respond to a harmless antigen that is perceived as a threat
what is immediate hypersensitivity?
acute, rapid allergic reaction
what is immediate hypersensitivity mediated by?
allergen-specific IgE antibodies
what is the treatment for immediate hypersensitivity (anaphylactic shock)?
adrenaline (epinephrine)
