CH 21 Flashcards
Immune system
not an organ system, but a cell population that inhibits all organ and defends the body from agents of disease.
Lymphatic system
- fluid recovery
- immunity
- lipid absorption
Fluid recovery
fluid continually filters from the blood capillaries into the tissue spaces.
- blood capillaries absorb 85%
- 15% water and plasma proteins returned.
Immunity
excess fluid
- passes through lymph nodes where immune cells stand guard against foreign matter
- activate a protective immune response
Lipid absorption
Lacteals in small intestine absorb dietary lipids that are not absorbed by the blood capillaries.
Lymph
clear, colorless fluid, similar to plasma, but much less protein.
(Like interstitial fluid)
Lymphatic capillaries (terminal lymphatics)
penetrate nearly every tissue in body.
- absent from CNS, cartilage, cornea, bone, and marrow.
- gaps big enough for bacteria and cells to enter.
endothelium creates valve like flaps that open when interstitial fluid pressure is high, and close when low.
Natural killer cells
large lymphocytes that attack and destroy bacteria, transplanted tissue, host cells infected with viruses or turned cancerous.
-immune surveillance
T lymphocytes (T cells)
mature in thymus
B lymphocytes (B cells)
Activation causes proliferation and differentiation into plasma cells the produce antibodies
-mature in bone marrow
Macrophages
(leukocytes)
- phagocytize tissue debris, dead neutrophils, bacteria, and other foreign matter.
- process foreign matter and display antigenic fragments to certain T cells alerting the immune system to the presence of the enemy.
- antigen-presenting cells (APC’s)
Dendritic cells
alter the immune system to pathogens that have breached their surface (within a certain tissue)
Reticular cells
Branched stationary cells that contribute to the storm of a lymphatic organ.
-act as APC’s in thymus where they stay
Lymphatic tissue
prevalent in body passages open to the exterior
-respiratory, digestive, urinary, and reproductive tracts.
Mucose-associated lymphatic tissue (MALT)
open to outside, where pathogens get through`
Lymphatic nodules (follicles)
Peyer patches:
constant feature of the lymph nodes, tonsils, and appendix
dense clusters in the ileum, the distal portion of the small intestine. (big lymph nodes)
Primary lymphatic organs
- red bone marrow and thymus
- site where T and B cells become immunocompetent: able to recognize and respond to antigens
Secondary lymphatic organs
- lymph nodes, tonsils, and spleen
- immunocompetent cells populate these tissues
Thymus
member of the endocrine, lymphatic and immune systems. (very active when young)
-Houses developing T cells,
-secretes hormones regulating their activity
-degeneration or involution with age.
(immune response less responsive)
_________ cells seal off cortex from medulla forming _______ barrier
produce?
reticular epithelial cells
blood-thymus barrier
-signaling molecules thymosin, thymopoietin, thymulin, interleukins, interferon. 2%
Lymph nodes
functions:
most numerous lymphatic organs.
-about 450 in young adult
cleanse lymph
act as site of T and B cell activation
(mostly around mucous membranes and orifaces)
Cervical lymph nodes
monitor lymph coming from head and neck
Axillary lymph nodes
receive lymph from upper limb and female breast
Thoracic lymph nodes
receive lymph from mediastinum, lungs, and airway.
Abdominal lymph nodes
monitor lymph from the urinary and reproductive systems
intestinal and mesenteric lymph nodes
in the groin and receive lymph from the entire lower limb
popliteal lymph nodes
receive lymph from the leg proper
When a lymph node is under challenges by and antigen:
- lymphadenitis: swollen, painful, movable node responding to foreign antigen.
- Lymphadenopathy: collectively term for all lymph node diseases.
stuck and painless= cancer
moveable and painful= fighting infection
Metastasis
cancer cells break free from the original, primary tumors, travel to other sites of the body, and establish new tumors.
- can easily enter lymphatic vessels.
- do not have CAM’s so they can move.they remove lymph nodes downstream.
Tonsils
patches of lymphatic tissue located at the entrance to the pharynx.
- guard against ingested orr inhales pathogens
- tonsillitis or tonsillectomy
3 main sets of tonsils
palatine- most often infected
lingual- pair at root of tongue
pharyngeal- single tonsil on wall of nasopharynx
Spleen
-functions
the bodies largest lymphatic organ.
- blood production in fetus
- blood reservoir (platelets)
- erythrocyte gravyard: RBC disposal.
highly vascular and vulnerable to trauma and infection
-ruptured requires splenectomy
Pathogens
environmental agents capable of producing disease,
-infectious organisms, toxic chemicals, and radiation.
first line of defense against pathogens
external barriers, skin, and mucous membranes, lacrimal fluid, saliva, defecation, urination, coughing, sneezing. IgA antibodies, gastric juice.
stomach= hydrochloric acid pH 2%
Second line of defense
severe non specific defense mechanisms.
- neutrophils and macrophages, complement, NK’s, eosinophils, interferon, inflammation, and fever.
- effective against a broad range of pathogens.
Third line of defense
the immune system
- defeats a pathogen, and leaves the body with a “memory” of it so it can defeat it in the future
- lymphocytes (dead if they get through)
skin
make sit difficult for microorganisms to enter body.
- toughness of keratin
- too dry and nutrient poor for microbial growth.
- defensins
- acid mantle
- commensal flora
Defensins:
acid mantle:
peptides that kill microbes by creating hole in their membranes.
thin film of lactic acid, fatty acids, which inhibits bacterial growth.
mucous membranes
digestive, respiratory, urinary and reproductive tracts are open and protected by these.
- mucous traps microbes
- LYSOZOME: enzyme destroys bacterial cell walls (IgA, commensal flora)
Subepithelial areolar tissue
viscous barrier of hyaluronic acid.
-hyaluronidase- enzyme used by pathogens to make hyaluronic acid less viscous.
Phagocytes
phagocytic cells witch a voracious appetite for foreign matter
5 types of leukocytes (2nd line)
neutrophils eosinophils basophils monocytes lymphocyte
Neutrohil
- produce a cloud of bactericidal chemicals
- first to arrive to bacterial infection
- create killing zone
(degranulation) - lysosomes discharge into tissue fluid.
Killing zone: respiratory burst
toxic chemicals
neutrophils rapidly absorb oxygen.
O2, H2O2, HCIO
-kill more bacteria with toxic chemicals than phagocytosis
Eosinophils
- especially in mucous membranes.
- stand guard against multicellular PARASITE, ALLERGENS, and other pathogens.
- kill worms by making superoxide, hydrogen peroxide, and toxic proteins
- Phagocytize antigen-antibody complexes
- limit HISTAMINE and other inflammatory chemicals.
Basophils
Leukotrienes:
Histamine:
Heparin:
Mast cells
secrete chemicals that aid mobility and action of other leukocytes.
activate and attract neutrophils and eosinophils
a vasodilator, which increases blood flow. (speeds delivery of leukocytes to the area)
inhibits clot formation (anticoagulant) (impede leukocyte mobility)
also secrete these, type of CT cell very similar to basophils.
wandering macrophages
actively seeking pathogens.
-widely distributed in loose CT
Fixed macrophages
microglia found in___
alveolar macrophages in___
Hepatic microphages in _____
phagocytize only pathogens that come to them.
Brain (CNS)
lungs
liver
What are the two families of antimicrobial proteins?
interferons
complement system
interferons
secreted by certain cells infected by viruses.
- no benefit to cell came from
- alert neighboring cells and protect (paracrine hormone)
- bind to surface receptors of near cells (activate second messenger systems)
- activate NK cells and macrophages
- NK cells destroy malignant cells
Complement system
activated complement brings about 4 methods of pathogen destruction:
3 routes of complement activation
a group of 30 or more globular proteins that make powerful contributions to both nonspecific resistance and specific immunity.
-synthesized mainly by liver,
inflammation, immune clearance, phagocytosis, cytolysis.
classical pathway, alternative pathway
Classical pathway
- requires antibody molecule to get started.
- part of specific community.
- antibody binds to antigen on surface of the pathogenic organism. (forms antigen-antibody Ag–Ab complex)
Alternative pathway
- nonspecific, does not require antibody.
- C3 breaks down in the blood to C3a and C3b. (C3b binds to tamest like tumor cells, viruses, bacteria, and yeast)
Inflammation
- C3a stimulates mast cells and basophils to secrete histamine and other inflammatory chemicals.
- Activates and attracts neutrophils and macrophages.
- speeds pathogen destruction
Immune clearance
- C3b binds with antigen-antibody complexes to RBC’s.
- these RBC’s circulate through liver and spleen.
- macrophages strip of complexes leaving RBC’s unharmed.
- Principle means of clearing foreign antigens from blood stream.
Phagocytosis
- Neutrophils and macrophages CANNOT phagocytize “naked” bacteria, viruses, or other pathogens.
- C3b assists them by opsonization.
Cytolysis
- C3b splits other complement proteins.
- Bind to enemy cell.
- attract more complement proteins–membrane attack complex forms (forms a hole in the target cell)(electrolytes leak in, water flows in rapidly, cell ruptures)
How do NK cells attack and destroy?
- NK’s bind to it.
- release perforins
- Secrete granzymes (induce apoptosis)
Fever
an abnormal election of body temperature.
- pyrexia, febrile
- results from trauma, infections, drug reactions, brain tumors, and other causes.
an adaptive defense mechanism.
- promotes interferon activity
- elevates metabolic rate and accelerates tissue repair
- inhibits reproduction of bacteria and viruses.
stages of fever
onset
stadium
defervescence
Reye syndrome
serious disorder in children younger than 15 following an acute viral infection such as chickenpox or influenza.
- swelling of brain neurons.
- 30% die
- triggered by aspirin for fever
Antipyretics: fever reducing medication by inhibiting PGE2.
5 signs of inflammation
redness swelling heat pain loss of function
Cytokines
class of chemicals that regulates inflammation and immunity.
- secreted mainly by leukocytes.
- neutrophils (acute), macrophages, lymphocytes (chronic)
3 major processes of inflammation
- mobilization of body defenses
- containment and destructions of pathogens
- tissue cleanup and repair
acute (8-10 days)
chronic (2 weeks+)
mobilization of defenses
margination:
diapedesis:
neutrophil behavior
selecting cause leukocytes to adhere to blood vessel walls.
(emigration) leukocytes squeeze between endothelial cells into tissue space.
priority of inflammation is to:
prevent the pathogens from spreading through the body.
- fibrinogen that filters into tissue fluid clots (forms a sticky mesh that walls off microbes)
- Heparin prevents clotting at site of injury.
Chemotaxis
attraction to chemicals such as bradykinin and leukotrienes that guide them to the injury site (diffusion gradient)
macrophages and T cells secrete ________ to stimulate leukopoiesis.
colony stimulating factor
Neutrophilia- bacterial infection
eosinophilia- elevated count in allergy or parasitic infection.
Monocytes
the primary agents of tissue cleanup and repair .
- arrive in 8012 hours and become macrophages
- engulf and destroy bacteria, damaged host cells, and dead and dying neutrophils.
Edema
Lymphatics:
contributes to tissue cleanup
collect and remove bacteria, bacteria, dead cells, proteins, and tissue debris better than blood capillaries.
Pus
_____: accumulation of pus in a tissue cavity.
accumulation of dead neutrophils, bacteria, other cellular debris, and tissue fluid form a pool of yellowish fluid.
Cyst/abcess
platelet drived growth factor
- stimulates fibroblasts to multiply.
- synthesizes collagen.
_______ delivers oxygen, amino acids, and other necessities for protein synthesis.
Hyperemia
increased ____ increases metabolic rate, speeds mitosis, and tissue repair.
heat
________ forms a scaffold for tissue reconstruction.
fibrin clot
____makes us limit the use if a body part so it has a chance to rest and heal.
Pain
congenital insensitivity to pain (CIPA): no pain
2 characteristics distinguish immunity from nonspecific resistance.
specificity
memory
cellular (cell-mediated) immunity
T cells
- lymphocytes directly attack and destroy foreign cell or diseased host cells.
- kills (injured) cells that harbor them.
- Cytotoxic T’s
Humoral (antibody-mediated) immunity
B cells
- mediated by antibodies that do not directly destroy a pathogen.
- indirect attack where antibodies assault the pathogen.
- B (plamsa) cells
Cytotoxic T’s
cells attacking cells
-endogenous antigens (own cells that are infected with viruses)
B (plamsa) cells
indirect attacks though antibodies
Natural active immunity
production of ones own antibodies or T cells as a result of infection or natural exposure to antigen.
Artificial active immunity
production of ones own antibodies to T cells as a result of vaccination against disease.
_______: consists of dead or attenuated (weakened) pathogens that stimulate the immune response without causing the disease
Vaccine
_______: Constant immunizations to stimulate immune memory to maintain a high level of protection.
Booster shots
Natural passive immunity
temporary immunity that results from antibodies produced by another person.
-fetus acquires antibodies from mother through placenta (IgG), milk (IgA, IgM, IgG)
Artificial passive immunity (emergencies)
temporary immunity that results from the injection of immune serum (antibodies) from another person or animal (rabbits)
-treatment for snakebites, etc.
Hapten
too small to be antigenic themselves.
- must combine with a host macro.
- create complex body sees as foreign.
- cosmetics, detergents, etc.
- penecillin
Negative selection
2 forms:
T cells that fail either test must be eliminated.
- clonal deletion: self reactive T cells die and macrophages phagocytize them.
- Anergy: self reactive T cells remain alive but unresponsive.
B cells that react to self-antigens undergo either ____ or ______, same as T cell selection.
anergy
clonal deletion
__________ synthesize antigen surface receptors, divide rapidly, produce immunocompetent clones.
Self-tolerant B cells
Antigen presenting cells (APC’s)
required to help T cells recognize exogenous antigens.
(2nd line alert 3rd line)
-dendritic cells, macrophages, reticular cells, and B cells function as APC’s.
Function APC’s depends on ___________
Major histocompatibility (MCH) complex proteins.
- act as id tags that label every cell belonging to you.
- structurally unique for everyone except twins.
antigen processing
-APC encounters antigen (foreign)
-internalizes it by endocytosis
-digests it into molecular fragments
-displays fragments (epitopes) in the grooves of the MHC protein.
(now lymphocytes can recognize) (cytotoxic T’s and helper T’s)
Cytotoxic T cells: (T8, CD8, or CD8+)
killer T cells
-effectors of cellular immunity; carry out attack. (endogenous antigens from own cells infected by virus)
Helper T cells: (T4, CD4, CD4+)
help promote Tc cell and B cell action and nonspecific resistance. (the generals)
-HIV attacks no 3rd line
Regulatory T cells: T-regs
inhibit multiplication and cytokine secretion by other T cells; limit immune response.
-suppress immune response
Memory T cells
descend from cytotoxic T cells
-responsible for memory in cellular immunity.
e R’s of immunity
recognize
react
remember
antigen presentation
(recognize) APC’s give info to cytotoxic and helper T’s.
cytotoxic= endogenous helper= both
Tc cells respond only ______ proteins. (our own injured cells)
MHC-1 proteins
Th cells respond only to ______ (from proteins)
MHC-2 proteins
T cell must check twice to see if it is really bound to a foreign antigen–______. why?
co-stimulation
- helps ensure the immune system does not launch an attack in the absence of an enemy.
- would turn against ones own body and injure out tissues.
Successful _____ will trigger ______
costimulation
clonal selection
B lymphocytes of humoral immunity produce __________ that bind to antigens and tag them for destruction by other means
antibodies
IgA
provides ____ passive immunity to newborns
found in mucous, saliva, tears, milk, and intestinal secretions (non-blood)
-prevents pathogens adherence (neutralize)
-natural
IgD
B cell transmembrane antigen receptor.
-thought to function in B cell activation by antigens
IgE
transmembrane protein on basophils and mast cells.
-produces immediate hypersensitivity reactions
IgG
constitutes 80% of circulating antibodies (blood and lymph)
-crosses placenta to fetus, secreted in secondary immune respinse, complement fixation, HDN?
HDN=hemolytic disease of newborn (2nd child in double if Rh+) take rogam
IgM
blood and lymph
-secreted in primary immune response, angulation of RBC’s, complement fixation. (transfusion reactions)
Neutralization
antibodies mask pathogenic region of antigen (IgA)
Complement fixation
Antigen binds to IgM or IgG, antibody changes shape, initiates complement binding which leads to inflammation, phagocytosis, immune clearance, or cytolysis.
– Primary defense against foreign cells, bacteria, and mismatched RBCs
Angulation
(IgM)
– Antibody has 2 to 10 binding sites; binds to multiple enemy cells immobilizing them from spreading
Precipitation
– Antibody binds antigen molecules (not cells); creates antigen–antibody complex that precipitates, phagocytized by eosinophils
primary immune response
– As plasma cells produce antibodies, the ____ (level in the blood plasma) rises
immune reaction brought about by the first exposure to an antigen.
-antibody titer (titer gets low need a booster)
secondary (anamnestic) response
if exposed to the same antigen
– Plasma cells form within hours
– IgG titer rises sharply and peaks in a few days
– Response is so rapid that the antigen has little chance to exert a noticeable effect on the body
– IgG remain elevated for weeks to years
• Conferring long-lasting protection
• Memory does not last as long in humoral immunity as in cellular immunity
• Boosters
Immune response may be:
– Too vigorous
– Too weak
– Misdirected against wrong targets
- allerige
- HIV
- autoimmune disease
hypersensitivity
- alloimmunity
- autoimmunity
- allergies
an excessive immune reaction
against antigens that most people tolerate
-reaction to transplanted tissue from another person.
-abnormal reactions to ones own tissues
Type I (acute) hypersensitivity
– Includes most common allergies
– IgE-mediated reaction that begins within seconds of exposure
– Usually subsides within 30 minutes, although it can be severe to fatal
– Clinical signs include:
• Local edema, mucus hypersecretion and congestion, watery eyes, runny nose, hives, and sometimes cramps, diarrhea, and vomiting
– Examples: food allergies, hay fever, and asthma—local inflammatory reaction to inhaled allergens
Anaphylaxis
– Immediate, severe type I reaction
– Local anaphylaxis can be relieved with antihistamines
anaphylactic shock
Severe, widespread acute hypersensitivity that occurs when an allergen is introduced to the bloodstream of an allergic individual
– Characterized by bronchoconstriction, dyspnea (labored breathing), widespread vasodilation, circulatory shock, and sometimes death
treatment: epinephrine causes bronchodilation.
Asthma
allergic (extrinsic) asthma:
nonallergic (intrinsic) asthma:
– Most common chronic illness in children
– Allergic (extrinsic) asthma is most common form • Respiratory crisis triggered by inhaled allergens
– Nonallergic (intrinsic) asthma
• Triggered by infections, drugs, cold dry air, exercise, or emotions
Type 2 (anti-body dependent cytotoxic)
Occurs when IgG or IgM attacks antigens bound to cell surfaces
• Examples: blood transfusion reaction, pemphigus vulgaris, and some drug reactions
Type 3 (immune complex)
– Occurs when IgG or IgM form antigen–antibody complexes
– Examples: autoimmune diseases—acute glomerulonephritis and in systemic lupus erythematosus, a widespread inflammation of the connective tissues
Type 4 (delayed)
– Cell-mediated reaction in which the signs appear 12 to 72 hours after exposure
– Begins when APCs in lymph nodes display antigens to helper T cells
• Examples: haptens in cosmetics and poison ivy, graft rejection, TB skin test, beta cell destruction that causes type 1 diabetes mellitus
Severe combines immunodeficiency disease (SCID)
hereditary lack of T and B cells
- no 3rd line
- must live in protective enclosures
- x linked recessive, boys get it.
Acquired immunodeficiency syndrome (AIDS)
– Non hereditary diseases contracted after birth
HIV
• HIV is transmitted through blood, semen, vaginal secretions, breast milk, or across the placenta
• Most common means of transmission – Sexual intercourse (vaginal, anal, oral)
– Contaminated blood products
– Contaminated needles
• Not transmitted by casual contact
• Undamaged latex condom is an effective barrier to HIV, especially with spermicide nonoxynol-9
Who eats and delivers HIV?
APC’s they don’t destroy it but it then destroys helper T’s
