Chapter 21 Immune System Flashcards
1
Q
Immune System
A
Provides resistance to disease
- Composed of two intrinsic defense systems
- Innate (nonspecific) defense system
- constituites first and second line of defense
- First line) Esternal body membranes (skin and mucosae)
- Second line) Antimicrobbial proteins, phagocytes, and other cells. (Inhibut spread of invaders, activates inflammation)
- Adaptive (specific defense system)
- Third line of Defesnse) Attacks particular foreign substances.
- Is a functional system rather than an organ system.
- Inntate and adaptive defenses are interertined
2
Q
Innate Defenses (Physical)
A
First/Second line of defense
- Surface barriers) skin and mucous membranes along with secretions
- Physical barrier reienforced with keritin to resist weak acids and bases as well as most microorganisms.
- Mucoseae provide similar protection
- Protective chemicals
- Acid) skin acidity creates acid mantle which inhibits growth
- Enzymes) Lyszysome of sliva, respritory mucus, lacrimal fluid, and enzymes in stomach kill many microorganisms
- Mucin) sticky mucas that lines digestive and respritory tract and traps mircoorganisms.
- Defensins) Antimicrobial peptides that inhibit growth
- Other chemicals) Lipids in Sebum and Dermicidin in Sweat are tocix to bacteria
3
Q
Internal Defenses (Second Line)
A
If microoganisms invade deeper tissues Phagocytes, Natural Killer (NK) cells, The Inflammatory response (Macrophages, mast cells, WBC’s and inflamatory chemicals) antimicrobial protiens, and Fever will trigger
- Many second-line defense cells have pattern recoginition receptors that can reconize and disarm microbes before they cause harm
- One class, Toll-Like Receptors (TLR’s) play a central role in triggering human immine responses
- Humans have 11 diffrent TLR’s that each reconize a particular microbe.
4
Q
Phagocytes
A
White Blood Cells (WBC’s) that ingest and digest foreign invaders
- Neutrophils) Most abundent type of WBC.
- become phagocytic to infectious materials
- Macrophages (Big eaters)
- derive from monocytes that leave blood stream aand enter tissues
- Most Robust (cheif) phagocytic cell
- Free macrophages) wander through tissue space (blood vessels)
- Fixed macrophages) pernenent residents of organs (liver, brain)
- Phagocytosis) Destruction of Forgien particles
- Phagocyte reconizes and adheres to pathogen’s carbohydrate “signature”
- Opsoniztion) immune system antibodies/ protiens add opsonis that coat pathogens. Act as handles for phagocytes to grab on to
- Some microorganisms have capsules that hide carbohydrates helping them evade phagocytosis.
- Cytoplasmic extension (psudopods) bind to particle and engulf into a vessicle called a Phagosome
- Phagosome fuses with lysosome > Phagolysosome
- Phagolysosome is acidified. Lysosomal enzymes digest particles
- Indigestible waste is exocytosed from the phagosome.
- Cells immine to phagocytosis are helped by T cells via
- The release of cell-killing free radicles
- Production of oxidizing chemicals (H2O2)
- Increase of pH and osmolarity of phagolysosome
5
Q
Natural Killer (NK) Cells
A
Nonphagocytic, Large Granular Lymphocytes that police blood and lymph
- Can kill cancer and virus-infected cells before adaptive immune system is activated.
- Attack cells that lack cell-suface recsptors calles MCH (major histcompatibility complex)
- Kill by inducin apoptosis (programed cell deth) in cancer cells and virus-infected cells.
- secrete chemicals that enhance inflammatory response.
6
Q
Inflammation
A
Triggerd whenever bodytissues are injured.
- Benifits of inflmation
- Prevents spread of damaging agents
- Disposes of pathogens
- Alerts adaptive immune system
- Sets the stage for repair
- Four Signs of acute infmation
- Redness, Heat, Swelling, Pain (somtimes function is impared)
- Stages of inflmmation
- Inflammatory chemical release
- released into ECF
- Major is histamine, Other inflammatory chemicals include Kinins, prostaglidins (PG’s) cytokines and complements if inflmation is caused by pathogens.
- All chemicals casue vasiodlation of local arteris, leaky capillaries, and attract phagocytes.
- Vasodilation and Increased Vascular Permiblity
- Hypermia) increased blood flow in response to vasodilation.
- Exudate) Antibodies leak into tissue due to increased permiability
- Edema) Delivers clotting protiens in a surge of fluid from lymph vessels. Clotting factors form structure for repair.
- Phagocyte Mobilization
- Leukocytosis) Release of nutrophils in response to lukeocytosis-inducing factors
- Migration) cell adehsion factors (CAM’s) from inflamed area signal cells to moce into place
- Diapedesis) neutrophils flatten and squeeze between endothelial cells to inflamed area
- Chemotaxis) Inflamatory chemical signal nutrophils to start chemotaxis to remove foreign debris.
- Nutrophils lead; macrophages follow
- Inflammatory chemical release
7
Q
Pus/ Abscess
A
- Pus) Creamy yellow mixture of dead neutrophils, tissue/cells, and living/dead pathogens
- An abcess forms when inflammatory mechanism fails to clear the debris from the area. The sac of puss is walled off and may need to be drained surgically to drain
8
Q
Antimicrobial Proteins
A
- Ehance innate defense by
- Attacking miroorganims directily
- Hindering microorganims abilty to reproduce
- Most important antimicrobial protiens
- Interferons (INFs)
- warn helthy neighboring cells and stimulate production of protiens that block viral reproduction
- degrade viral DNA
- IFN α and β protiens) activate NK cells
- IFN γ protiens) Activate macrophages
- Complement System
- at least 20 plasma protiens that circulate in incactive form. Included protiens C1-C9 and factors B, D, and P
- Major mechanism for destroying forgein substances and enhances inflammation
- Ehnances both innate and adaptive defenses
- Complement Activation
- Classical Pathway) Abtibodies bind to compelment protiens
- Lectin Pathay) Lectins are protiens molcecules that activate complement protiens
- Alternative Pathway) C3 is spontaneously activated and activates compliment protiens.
- Cell lysis begins when C3 splits its C3b componat binds to the target cell. This triggers the Membrane Attack Complec (MAC)
9
Q
Fever
A
Abnormally high body temp that is systemic response to invading microorganims
- Lukeocytes and macropgages release pyrogens
- Pyrogens act on body’s themostat in hypothalamus which raises the body them
- Causes liver/ spleen to hold iron and zinc which slows bacterial growth
- Increase metabolic rate which increases rate of repair.
10
Q
Adaptive Defenses
A
Adaptive immine system is a specific defensive system that eliminated almost any pathogen or abnormal cell in the body.
- Activies
- Amplifies inflammatory response
- Activates complement
- Must be primed by inital exposure to specific forgein substance which takes time.
- Charcteristics of Adaptive immunity
- Specific) Targets specific antigens
- Systemic) Not restriceted to inital site
- Memory) Remembers and mounts srtonger attacks when enountering an antigen for a subsequent time
11
Q
Two branches of adative immune system
A
- Humoral (anitbody-mediated) immunuty
- Antibodies produced by lympocytes circulate freely
- Bind to target cell to temoporally inactive and mark them for destruction by phagocytes or compliment,
- Cellular (cell-mediated) immunity
- Lympcytes act directily against target cells
- Directily) Killing infected cells
- Indirecityly) Releasing chemicals that increase inflammatory response or activate other lymphocytes or macrophages
*
12
Q
Antigens
A
Substances that can mobilize adaptive defenses and provoke and immune response.
- Targets of all adaptice immine response
- Large, complex moleculea not normally found in the body
- charcteristice of antigens
- can be complete or hapten (incomplete)
- Conatain antigentic deterninants
- can be a self-antigen
13
Q
Complete Antigens or Haptens
A
- Complete antigens) have two functional properties
- Immunogenicity) ability to stimulate proliferation of speciifc lymocytes
- Reactivity) ability to react with activated lympocytes and antibodies
- Incomplete antigens also called haptens
- moleculeas are too small to be seen and not immnogenic by themselvles.
- The combination of a hapten and protein is seen as a forgein invader by the body.
14
Q
Antigenic Detrminants
A
- Parts of anigen that antibodies or lympocyte receptors bind to
- Mobilize several diffrent lympocyte populations; Form different kinds of antibodies agaisnt them
15
Q
Self-Antigens (MHC proteins)
A
- Self-Antigens) all cells that are covered with a veriety of proteins located on the suface that are not anitgenic to ones self but could be antigenic to others.
- occurs during transfusions or graphs
- Major Histocompatibity Complex (MHC) are unique to each indvuidal
- T lymphocytes can reconize only antigens that are presented on MHC proteins
