m9 + 10 lecture - immune system Flashcards
what does the immune system do?
- protects the body from invasion of foreign pathogens
ex. ) bacteria, viruses, mold, fungi, parasites
what are the two parts of the immune system?
1) innate/nonspecific system
- this system is built in and always working to prevent infections
2) adaptive/specific system
- this system needs to be activated and is very specialized in fighting bacteria or viruses
what is the innate immune system?
- built into the body’s nature structure
- always working against pathogens,
- provide immediate response
- usually can take care of a pathogen before it causes a reaction
- localized in its effect
what is the first line of defense?
surface barriers
aspects of the first line of defense?
cutaneous membrane (skin)
—-> dead cells create barrier to pathogen
mucus membranes ( nose, mouth, GI tract, urogenital area)
—-> traps debris + pathogens in mucus before they come in contact w/ cells
acid mantle
—-> low pH of the skin, vagina, + stomach destroys most bacteria on the surface
lysozyme
—-> an antibacterial enzyme
—-> secreted by the sebaceoues glands, salivary glands, lacrimal glands + Brunner’s glands
what is the second line of defense?
internal innate defenses
- these are activated if the pathogen breaks through the surface barriers
how does inflammation occur?
swelling in response to tissue damage or chemical release
- inflammation is caused by histamine
- pain is caused by Bradykinin (both are from basophils/mast cells)
how do you identify inflammation?
hyperemia - increased BF to tissues
- heat = inc. BF
- redness = blood accumulation
- swelling = fluid accumulation
- pain = tissue damage
… due to exudate
what is the reason for inflammation?
- isolates the area
- increases blood flow for healing
- initiates chemotaxis –> WBC attraction
- allows entry of clotting proteins, and complement
what WBC types are phagocytes?
neutrophils
-acute bacterial infections
macrophages
- chronic bacterial or viral reactions
—> respiratory burst - a process that occurs when cells increase their oxygen consumption and metabolism, and release reactive oxygen species (ROS)
what are other WBC types?
mast cells (basophils)
- massive histamine release, allergies (inflammatory response)
natural killer cells (NK) - hybred lymphocyte
- called this because it is always on the lookout
- can recognize cells the immune system can not
- very important in fighting cancer (can dect mutations and kill them before becoming cancerous)
- injects Perforin to cause lysis
what are the three types leukocyte mobilization?
- leukocytosis
- chemotaxis
- diapedesis
what is leukocytosis?
- massive production and release of neutrophils from the bone marrow
what is chemotaxis?
- migration of WBCs in response to chemical release
what is diapedesis?
- the movement of WBCs through a vessel wall and tissue cells
what is complement?
- series of plasma proteins
- works together with all other aspects of the immune system
- complement fixation - attaches to bacteria
- opsonization - helps to optimize the immune system
- lysis - process of breaking down a cell’s membrane, which releases the cell’s contents
what is an interferon?
- released by virally infected cells
- activates nearby cells WBCs and prevents the spread of the virus
- types: alpha, beta, gamma
what are pyrogens?
- released by macrophages to stimulate the hypothalamus - to raise body temp.
- causes elevated temp./ metabolism + a fever
- its good to destroy bacterial proteins + helps speed up healing
- feed fevers healthy food, sugars cause food coma for WBCs
- fever is not dangerous until it reaches 104+/ 106 can be deadly
what is adaptive immune system? (third line of defense)
- activated when exposed to a pathogen
- called the specific immune system
- results in immunity from a virus or bacteria
- is specific for an antigen
what are the two parts of the adaptive immune system?
humoral immune response - B cells
- antibodies are released to fight the antigen
cell mediated immune response - T cells
- T cells organize and fight the antigen directly
what are helper t cells?
“general” - organizes + makes decisions (by releasing chemicals called cytokines)
- these cells organize the cell mediated response
- w/o these cells there can be no response
- not only stimulate T cells but also B cells to proliferate
what are cytotoxic T cells?
- need to be activated by infection, are specific
- killers of the cell mediated immune response
- they can attach to infected T cells or pathogens and inject them with Perforin (causes lysis)
what are B cells?
- used in humoral immune response
- found in lymph nodes
- proliferate into plasma cells, which produce antibodies + memory B cells
what are antigen presenting cells (APCs)?
“scouts” at intelligence agency (collect info.)
- dendritic cells (mostly macrophages, can be B cells)
- found in lymph nodes, surface membranes, spleen, + liver
- activate helper T cell - releases interleukin 1 ( a chemical communicator)
what are the types of antigens?
1) MHC antigens
2) complete antigens
3) haptens
what is an MHC antigen?
- self antigens that WBCs are trained to identify (ex. blood type)
what are complete antigens?
immunogenicity
- its size and shape (antigenic determinants - diff. than self)
- it’s able to activate the immune system to prod. antibodies
reactivity
- reacts w/ antibodies and WBCs
what is immunogenicity?
the ability of a substance to cause an immune response in an organism
what are haptens?
- half antigens that can react w/ a self protein and cause a reaction (allergies - nonpathogenic objects causing an allergy)
how do we acquire immunity?
naturally or artificially
what are the two types of naturally acquired immunity?
active
- infection; contact w/ pathogen
passive
- antibodies pass from mother to fetus via placenta or to infant in her milk
what are the two types of artificially acquired immunity?
active
- vaccine, dead or attenuated pathogens
passive
- injection of immune serum (gamma globulin)
what are the four steps in the the primary immune response?
1) antigen challenge
2) proliferation
3) antibody prod./ immobilize + destroy
4) immunological memory: immunity
how long does the primary immune response take to start?
3-5 days
what occurs in the antigen challenge? (1st step - primary immune response)
- first encounter w/ an antigen when it is identified as foreign
- its antigenic determinants are identified
- 3-6 days long
what occurs in proliferation? (2nd step - primary immune response)
- cells will begin to clone and multiply in great numbers
clonal selection
- helps to develop specific cells to fight the antigen
- activated B and T cells are prod.
- memory cells develop which are long lived and prod. immunity
what occurs in antibody prod./immobilize and destroy? (3rd step - primary immune response)
- helper t cells organize
- cytotoxic cells attack the infected cells
what are plasma cells? antibody prod./immobilize and destroy (3rd step - primary immune response)
- prod. immunoglobulins (antibodies)
- short lived - 4 to 5 days
large antibody factories
- filled w/ rough ER
- prod. up to 2000 molecules/sec
what occurs in immunological memory/immunity? (4th step - primary immune response)
memory cells
- B cells, helper T cells, cytotoxic T cells
- maintain the antigenic signature of the foreign antigen
- are always looking for the antigen to reappear
what is the secondary immune response?
- is much more aggressive and rapid due to the memory cells
- does not require the antigen challenge (antigen’s already been identified)
- 3 to 5 days for full scale response
- each subsequent reaction is 10x more aggressive (reason why bee sting can be fatal the 2nd time)
what are antibodies?
- called immunoglobulins or Ig
- made from looping polypeptide chains
- T or Y shaped
- prod. by plasma cells
—> appear like a lobster and each has two binding sites, where they can react to an antigen
what are the antibody classes?
1) IgD
2) IgM
3) IgG
4) IgA
5) IgE
what is IgD? (antibody class)
- triggers antigen challenge
- always attached to a B cell and activates the B cell in a primary exposure
what is IgM? (antibody class)
- only one to exist as a pentamer
- genetically prod.
- readily causes agglutination (blood typing reaction) and activates complement
what is IgG? (antibody class)
- most abundant type
- prod. by plasma cells in primary and secondary responses
- crosses the placenta to provide passive immunity or may attack the fetus in an Rh reaction
what is IgA? (antibody class)
- normally a dimer shape
- found in bodily secretions: saliva, tears, sweat, milk, and intestinal juice
- neutralizes pathogens on the skin
what is IgE? (antibody class)
- found within the skin and mucus membranes
- responsible for causing mast cells to release massive amts. of histamine (allergies can be made worse from this)
what are the actions of antibodies?
- opsonization (“optimizes” - process by which pathogens are marked for destruction by phagocytes)
- neutralizes the pathogen
- activates complement
what are immunodeficiencies?
- diagnosed as a problem in the effectiveness of the immune system - specifically WBCs
ex.) SCID - severe combined immunodeficiency
AIDS - acquired immunodeficiency syndrome
what is SCID?
- missing B cells
- a genetic defect that effects the lymphocytes
- the child has very little protection against disease
what is AIDS?
- caused by the HIV virus - advanced version
- this retro-virus attacks the Helper T cells and inactivates the cell mediated system
- the virus multiplies in the lymph nodes and will steadily eliminate the memory cells from the system
- normally death is caused by pneumococcus Carini
- leading killer of people 25 to 44
what are the types of immunosuppression?
stress induced
- cortisol = Cushing’s syndrome
drug induced
- Rhogam (Rh+)
- chemotherapy
what are autoimmune diseases?
- a hyperactivity of the immune system, where the body’s cells “look” foreign
examples: - multiple sclerosis, juvenile diabetes (type 1), rheumatoid arthritis, myasthenia gravis, lupus
causes: - age
- ineffective programming of lymphocytes
- new self antigens appear as mutations
- foreign antigens look like self antigens
