Chapter 21: The Lymphatic and Immune System Powerpoint Outline Flashcards
agents capable of producing disease
includes viruses, bacteria, and fungi
Pathogens
There are ______ lines of defenses against pathogens
three
First line of defense includes:
skin and mucous membranes
Second line of defense includes:
several nonspecific defense mechanisms
Third line of defense includes:
the adaptive immune system. (defeats a pathogen, and leaves the body with a “memory” of it so it can defeat it faster in the future)
- guard equally against a broad range of pathogens
- they lack capacity to remember pathogens
- three kinds (protective cells, protective proteins, & protective processes)
Nonspecific Defenses
Nonspecific Resistance
- body must develop separate immunity to each pathogen
- body adapts to a pathogen and wards it off more easily upon future exposure
Specific or Adaptive Immunity
Nonspecific Resistance
- toughness or keratin
- too dry and nutrient poor for microbial growth
- produces dermicidin, defensins, and cathelicidins that kill microbes
Skin
(External barrier)
(1st Line of Defense)
- mucus physically traps microbes
- lysozyme: enzyme destroys bacterial cell walls
- four systems = reproductive, digestive, respiratory, urinary
Mucous membranes
(External barrier)
(1st Line of Defense)
- lower pH inhibits bacterial and fungal growth
- sweat, sebum, vagina, stomach
“Acid mantle”
1st Line of Defense
- penetration of microbes slowed by moving them out of susceptible area
- urination, salivation, lacrimation, mucus-ciliary escalator
“Fluid flow”
1st Line of Defense
What consists of:
- protective cells = leukocytes, macrophages, and natural killers (NK) cells
- protective proteins = interferons and complement proteins
- protective responses = fever and inflammation
2nd Line of Defense
Name this WBC:
- kill bacteria using phagocytosis
- can kill by producing a respiratory burst
- lysosomes degranulate releasing bactericidal chemicals
- creates a killing zone around this WBC
Neutrophils
Name this WBC:
- guard against parasites, allergens, (allergy-causing agents), and other pathogens
- kills tapeworms and roundworms by producing superoxide, hydrogen peroxide, and toxic proteins
Eosinphils
Name this WBC:
- secrete histamine: promotes inflammation
- secretes heparin: inhibits clot formation
- Mast cells also secrete these substances; similar to this WBC but found in other connective tissue
Basophils
Name this WBC:
-leaves blood and transform into macrophages
Monocytes
- wandering macrophages actively seek pathogens
- Fixed macrophages phagocytize only pathogens that come to them
What system is this?
Macrophage System
- type of lymphocyte that is not a B-cell or T-cell
- continually patrol body looking for pathogens and diseased host cells
- attack and destroy bacteria, transplanted cells, cells infected with viruses, and cancer cells
Natural Killer (NK) Cells
- proteins that inhibit microbial reproduction and provide short-term, nonspecific resistance to pathogenic bacteria and viruses
Protective Proteins
2nd Line of Defense
List the two families of antimicrobial proteins
- interferons
- complement system
- secreted by certain cells infected by viruses
- of no benefit to the cell that secretes them
- alerts neighboring cells and protects them
Interferons
What happens to the original cell that secreted the interferon?
It dies; it tried to protect everyone around it
- group of 30 or more proteins
* four methods of pathogen destruction when activated
Complement System
Inflammation, Immune Clearance, Phagocytosis, and Cytolysis are mechanisms of _________ _________
Complement System
Stimulates mast cells and basophils to secrete histamine
Inflammation
- binds with antigen-antibody (Ag-Ab) complexes to RBCs
- when these RBCs circulate through liver and spleen, macrophages strip off and destroy the Ag-Ab complexes leaving RBCs unharmed
- principal means of clearing foreign antigens from the bloodstream
Immune Clearance
*assists phagocytes by opsonization (coating microbial cells)
Phagocytosis
- forms a membrane attack complex
- forms a hole in the target cell
- electrolytes leak out, water flows in rapidly, cell ruptures
Cytolysis
Protective responses:
2nd Line of Defense
- fever
- inflammation
- both slow the spread of infections
- Hypothalamus elevates body temperature
- Response to pyrogens (exogenous or endogenous)
Fever
Moderate fever is helpful:
- promotes interferon activity
- elevates metabolic rate and accelerates tissue repair
- inhibits reproduction of bacteria and viruses
- local response to tissue injury, including trauma and infection
- general purposes of inflammation; limits spread of pathogens then destroys them, removes debris from damaged tissue, initiates tissue repair
Inflammation
List the four cardinal signs of inflammation
- redness, swelling, heat, and pain
How many steps does inflammation have?
5
Release of inflammatory chemicals such as cytokines (ex. histamine)
Which step of inflammation is this?
Step 1
Vascular Changes: the chemicals cause vasodilation which increases blood flow to the area - produces redness & warmth; the chemicals will increase permeability of the capillaries, which increases leakage into the interstitial areas - produces swelling (edema) & pain - moves material into lymphatic vessels
Which step of inflammation is this?
Step 2
Clotting factors (now in the interstitial area) form clots to wall off the area. Prevents spread of bacteria. Heparin prevents clotting directly at the injury site.
Which step of inflammation is this?
Step 3
Attraction of neutrophils, then macrophages to the area (phagocyte mobilization)
Which step of inflammation is this?
Step 4
Tissue Repair
Which step of inflammation is this?
Step 5
How many steps does phagocyte mobilization?
4
Leukocytosis: release of neutrophils from bone marrow in response to leukocytosis-inducing factors from injured cells
Which step of phagocyte mobilization is this?
Step 1
Margination: neutrophils cling to walls of capillaries in inflamed area
Which step of phagocyte mobilization is this?
Step 2
Diapedesis of neutrophils
Which step of phagocyte mobilization is this?
Step 3
Chemotaxis: inflammatory chemicals promote positive chemotaxis of neutrophils
Which step of phagocyte mobilization is this?
Step 4
- mobilization of defenses
- neutrophil behavior
- selectins cause leukocytes to adhere to blood vessel walls
Margination
- mobilization of defenses
- neutrophil behavior
- leukocytes squeeze between endothelial cells into tissue space
Diapedesis (emigration)
Containment/destruction of pathogens
- name the WBC that quickly responds to and kills bacteria
- phagocytosis
- respiratory burst
Neutrophils
Containment/destruction of pathogens
- name the cells that stimulate leukopoiesis
- neutrophilia = 5,000 cells/ul to 25,000 cells/ul in bacterial infection
- eosinophilia - allergy or parasitic infection
Macrophages and T-cells
- accumulation of dead neutrophils, bacteria, cellular debris, and tissue fluid
Puss
Which WBC is the primary agent of tissue cleanup and repair?
- they arrive in 8 to 12 hours and become macrophages
- engulf and destroy bacteria, damaged host cells, and dead and dying neutrophils
Monocytes
Edema contributes to:
- tissue cleanup
- forces more fluid into lymphatic system
Platelet-derived growth factor stimulates:
fibroblasts
Lists the two characteristics of Adaptive (Specific) Immunity
- Specificity
- Memory
- immunity directed against a particular region
Which characteristic of adaptive (specific) immunity is this?
Specificity
- when reexposed to the same pathogen, the body reacts so quickly that there is no noticeable illness
Which characteristic of adaptive (specific) immunity is this?
Memory
The forms of immunity are:
- Cellular (cell-mediated) immunity
- Humoral (antibody-mediated) immunity
- Natural active immunity
- Artificial active immunity
- Natural passive immunity
- Artificial passive immunity
- T-cells directly attack and destroy foreign cells or diseased host cells
- Gets rid of intracellular pathogens by killing the cell
Which form of immunity is this?
Cellular (cell-mediated) immunity
- B-cells —> plasma cell —> antibodies
- Antibodies do not directly destroy a pathogen but tag it for destruction
- Primarily works on extracellular infections
Which form of immunity is this?
Humoral (antibody-mediated) immunity
*Production of one’s own antibodies or T cells as a result of infection or natural exposure to antigen
Which form of immunity is this?
Natural active immunity
*Production of one’s own antibodies or T cells as a result of vaccination against disease
Which form of immunity is this?
Artificial active immunity
- consists of dead or attenuated (weakened) pathogens that stimulate the immune response without causing the disease
Vaccine
- periodic immunizations to stimulate immune memory to maintain a high level of protection
Booster Shots
- Temporary immunity that results from the injection of immune serum (antibodies) from another person or animal
- Treatment for snakebite, botulism, rabies, tetanus, and other diseases
Which form of immunity is this?
Artificial passive immunity
- Temporary immunity that results from antibodies produced by another person
- Fetus acquires antibodies from mother through placenta, breastmilk
Which form of immunity is this?
Natural passive immunity
- any molecule that triggers an immune response
- usually large complex molecules
- regions of an antigen that stimulate immune response: epitopes
Antigens
- too small to be antigenic by themselves
- but if combined with a host macromolecule, can trigger an immune response
- cosmetics, detergents, industrial chemicals, poison ivy, animal dander, penicillin
Haptens
List the major cells of the immune system:
- lymphocytes
- macrophages
- dendritic cells
The three classes of lymphocytes:
- T lymphocyte (T cells)
- B lymphocyte (B cells)
- Natural Killer (NK cells) - 2nd line of defense
Three stages in life of T Cell:
- born in bone marrow
- educated in thymus
- deployed to carry out immune function
Within the thymus, T Cells:
- develop surface antigen receptors
- with receptors, the T cells are now immunocompetent: capable of recognizing antigens presented to them
- T cells tested: need to be able to recognize self-antigens, not react to the self antigen, only 2% of T cells pass the test
immunocompetent T cells that have not yet encountered foreign antigens
naive lymphocyte pool
naive T cells leave thymus and colonize lymphatic tissues and organs everywhere in the body
deployment
Three stages in life of B cell:
- born in bone marrow
- educated in bone marrow
- deployed to carry out immune function
Immunocompetent B and T cells
- Each B cell and T cell displays a unique type of receptor that responds to a specific antigen
- It is genes, not antigens, that determine which foreign substances our immune system will recognize and resist
T cells cannot recognize antigens on their own, so this type of cell is required.
- dendritic cells, macrophages, reticular cells, and B cells function as this type of cell
Antigen-presenting cells (APCs)
Function of APCs depends on this protein.
- act as cell “identification tags” that label every cell of your body as belonging to you
- structurally unique for each individual, except for identical twins
Major histocompatibility (MHC) complex proteins
Two classes of MHC proteins:
- MHC-1
* MHC-II
The class of MHC proteins that:
- are produced by all nucleated cells
- will display either normal self-antigens (ignored) or abnormal viral/cancer antigens (attached)
- only Cytoxic T cells respond to this protein
MHC-1
The class of MHC proteins that:
- occur only in APCs
- display only foreign antigens
- only helper T cells respond to this protein
MHC-II
- APC encounters antigen
- Internalizes it by endocytosis
- Digests it into molecular fragments
- Displays fragments (epitopes) in the grooves of the MHC protein
Antigen-Presenting Cells / Antigen Processing
- wandering T cells inspect APCs for displayed antigens
- if APC only displays a self antigen, the T cell disregards it
- if APC displays a nonself antigen that the T cell is programmed to recognize, the T cell initiates an immune attack
Antigen-Presenting Cells / Antigen Presenting
List the 4 classes of T-cells
identified by protein markers {CD receptors}
- Cytotoxic T cells
- Helper T cells
- Regulatory T cells
- Memory T cells
- killer T cells have CD8 receptors
- “effectors” of cellular immunity; carry out attack on enemy cells
which class of T-cells is this?
Cytotoxic T cells
- have CD4 receptors
- help promote Tc cell and B cell action and nonspecific resistance
which class of T-cells is this?
Helper T cells
- inhibit multiplication and cytokine secretion by other T cells; limit immune response
- have CD4 receptors
which class of T-cells is this?
Regulatory T cells
- responsible for memory in cellular immunity
which class of T-cells is this?
Memory T cells
Both cellular and humoral immunity occur in three stages:
- recognition (recognize)
- attack (react)
- memory (remember)
- a defensive gamma globulin
- found in blood plasma, tissue fluids, body secretions, and some leukocyte membranes
Immunoglobulin (Ig)
Five categories of Immunoglobulins:
IgG, IgA, IgM, IgD, IgE
(Immunoglobulin)
- 80% of total
- most abundant and diverse; able to cross the placenta; protects against a wide diversity of bacteria, viruses, and toxins
IgG
(Immunoglobulin)
- 10-15% of total
- prevents attachment of pathogens to mucosa; found in saliva, tears, breast milk (too large to cross placenta)
IgA
(Immunoglobulin)
- 5-10% of total
- found primarily in blood; first to be formed in primary response {indicates a current infection}; responsible for ABO incompatibility response
IgM
(Immunoglobulin)
- 0.2% of total
- important in B cell activation
IgD
(Immunoglobulin)
- 0.002% of total
- binds to mast cells and basophils, causing histamine release when activated
IgE
Antibodies have four mechanisms of attack against antigens:
- neutralization
- complement fixation
- agglutination
- precipitation
- antibodies mask pathogenic region of antigen
neutralization
- leads to inflammation, phagocytosis, immune clearance, or cytolysis
complement fixation
- antibody has 2 to 10 binding sites; binds to multiple enemy cells, immobilizing them from spreading
agglutination
- antibody binds antigen molecules (not cells); creates antigen-antibody complex that precipitates, allowing them to be removed by immune clearance or phagocytized by eosinophils
precipitation
Classes of Antibodies:
- B cells can switch antibody but retain antigen specificity
- IgM at first; then IgG
- secondary responses are mostly IgG
(Immunological Memory)
- have a lag period during the first exposure to a specific antigen {3 to 6 days}
- peak levels of the antibody in about 10 days
Primary immune response
(Immunological Memory)
- reexposure to the same antigen
- memory cells respond within hours, not days
- antibody (mostly IgG) levels peak in 2 to 3 days at much higher levels than in the primary response
Secondary (anamnestic) immune response
Cellular Immunity:
- Best for:
- Effector cells:
- Memory:
- intracellular pathogens, cancer cells, transplanted tissues
- cytotoxic T cells (helped by Helper T cells)
- T cell recall response
Humoral Immunity:
- Best for:
- Effector cells:
- Memory:
- extracellular pathogens, toxins, venoms, allergens, mismatched RBCs
- plasma cells (develop from B cells and helped by Helper T cells)
- secondary (anamnestic) response
Immune response may be:
- too vigorous
- too weak
- misdirected against wrong targets
an excessive immune reaction against antigens that most people tolerate
hypersensitivity
four types of hypersensitivity disorders:
- Type I
- Type II
- Type III
- Type IV
- acute (immediate) hypersensitivity
- very rapid response
- based on antibodies
Type I
- subacute hypersensitivity
- slower onset (1 to 3 hours after exposure)
- last longer (10 to 15 hours)
- based on antibodies
Type II and Type III
- delayed cell mediated response
- signs appear 12 to 72 hours after exposure
- cosmetics, poison ivy, graft rejection, TB skin test
Type IV
