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Lina Le Period 6 Immune System - Coggle Diagram
Lina Le Period 6 Immune System
Major Functions of the Lymphatic and Immune System
Lymphatic System
the function of the lymphatic system is to maintain the fluid levels in the body tissues by removing all fluids that leak out of the blood vessels
optimal in the functioning of the general and specific immune responses
Immune System
main function is to defend the body against disease
Location of Lymphatic organs and their Functions
Spleen
cleanses blood and removes aged or defective RBC
site for lymphocyte activation and proliferation
stores platelets, monocytes, and iron
Malt
prevent pathogens from penetrating mucous membrane
site for lymphocyte activation and proliferation
Lymph Nodes
cleanse lymph
site for lymphocyte activation and proliferation
Thymus
site of T cell maturation
Purpose and examples of the First, Second, and Third Line of Defense
Second Line of Defense
Second Line of Defense: antimicrobial proteins, phagocytes, and other cells
inhibit spread of invaders
Inflammation most important mechanism
many second-line cells have pattern recognition receptors that recognize and bind tightly to structures on microbes, disarming them before they do harm
Internal Defenses: necessary is microorganisms invade deeper tissues
Phagocytes
Phagocytes: white blood cells that ingest and digest (eat) foreign invaders
Neutrophils: most abundant phagocytes, but die fighting; become phagocytic on exposure to infectious material
Macrophages: develop from monocytes and are chief phagocytic cells; most robust phagocytic cell
Engulf and destroy pathogens that breach surface membrane barriers; macrophages also contribute to adaptive immune responses
Natural killer (NK) cells
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 “self” cell-surface receptors
Kill by inducing apoptosis in cancer cells and virus-infected cells
Secrete potent chemicals that enhance inflammatory response
Promote apoptosis (cell suicide) by directly attacking virus-infected or cancerous body cells; recognize general abnormalities rather than specific antigens
Inflammatory response (macrophages, mast cells, WBCs, and inflammatory chemicals)
Inflammation is triggered whenever body tissues are injured
Injuries can be due to trauma, heat, irritating chemicals, or infections by microorganisms
Benefits of inflammation
Disposes of cell debris and pathogens
Alerts adaptive immune system
Prevents spread of damaging agents
Sets the stage for repair
Four cardinal signs of acute inflammation
Redness, Heat, Swelling, Pain
Sometimes a fifth sign, impairment of function, is seen if movement or use of area is hampered
Stages of Inflammation
Vsodilation and increased vascular permeability
Phagocyte mobilization
Neutrophils flood area first; macrophages follow
If inflammation is due to pathogens, complement is activated; adaptive immunity elements arrive
Inflammatory chemical release
Chemicals are released into ECF by injured tissues or immune cells
Other inflammatory mediators besides histamine
Kinins, prostaglandins (PGs), cytokines and if pathogens are involved, complement
cause vasodilation of local arterioles
make capillaries leaky
many attract phagocytes to area
Prevents injurious agents from spreading to adjacent tissues, disposes of pathogens and dead tissue cells, and promotes tissue repair; released inflammatory chemicals attract phagocytes (and other immune cells) to the area
Antimicrobial proteins (interferons and complement proteins)
Complement: a group of bloodbone proteins that, when activated lyse microorganisms, enhance phagocytosis by opsonization, and intensify inflammatory and other immune responses
Interferons: proteins released by virus-infected cells and certain lymphocytes; act as chemical messengers to protect uninfected tissue cells from viral takeover; mobilize immune system
Fever
Systemic response initiated by pyrogens; high body temperature inhibits microbes from multiplying and enhances body repair processes
Third Line of Defense
First Line of Defense
First Line of Defense: external body membranes
Surface Barriers: skin and mucosa
Keratin is resistant to weak acids and bases, bacterial enzymes, and toxins
Mucosae provide similar mechanical barriers
Physical barrier to most microorganisms
Skin and mucous membranes produce protective chemicals that inhibit or destroy microorganisms
Mucin: sticky mucus that lines digestive and respiratory tract traps microorganisms
Enzymes: lysozyme of saliva, respiratory mucus, and lacrimal fluid kills many microorganisms; enzymes in stomach kill many microorganisms
Acid: acidity of skin and some mucous secretions inhibits growth; called acid mantle
Surface barriers breached by nicks or cuts trigger the internal second line of defense that protects deeper tissues
Intact skin epidermis: Forms mechanical barrier that prevents entry of pathogens and other harmful substance into body
Keratin: provides resistance against acids, alkalis, and bacterial enzymes
Acid Mantle of Skin: skin secretions (sweat and sebum) make epidermal surface acidic, which inhibits bacterial growth, also contain various bactericidal chamicals
Intact mucous membranes: Form mechanical barrier that prevents entry of pathogens
Cilia: propel debris-laden mucus away from nasal cavity and lower respiratory passages
Gastric Juice: contains concentrated hydrochloric acid and protein-digesting enzymes that destroy pathogens in stomach
Acid Mantle of Vagina: Inhibits growth of most bacteria and fungi in female reproductive tract
Nasal Hairs: filter and trap microoganisms in nasal passages
Mucus: traps microoganisms in respiratory and digestive tracts
Lacrimal Secretion (tears); Saliva: continuously lubricate and cleanse eyes (tears) and oral cavity (saliva); contain lysozyme, an enzyme that destroys microorganisms
Urine: normally acid pH inhibits bacterial growth; cleanses the lower urinary tract as it flushes from the body
Innate (natural) Immune Defenses and Adaptive (acquired) Immune Defenses
Innate Immune Defense
Contains the First and Second lines of defense; used to stop attacks by pathogens
First Line of Defense: external body membranes
Surface Barriers: skin and mucosa
Keratin is resistant to weak acids and bases, bacterial enzymes, and toxins
Mucosae provide similar mechanical barriers
Physical barrier to most microorganisms
Skin and mucous membranes produce protective chemicals that inhibit or destroy microorganisms
Mucin: sticky mucus that lines digestive and respiratory tract traps microorganisms
Enzymes: lysozyme of saliva, respiratory mucus, and lacrimal fluid kills many microorganisms; enzymes in stomach kill many microorganisms
Acid: acidity of skin and some mucous secretions inhibits growth; called acid mantle
Surface barriers breached by nicks or cuts trigger the internal second line of defense that protects deeper tissues
Intact skin epidermis: Forms mechanical barrier that prevents entry of pathogens and other harmful substance into body
Keratin: provides resistance against acids, alkalis, and bacterial enzymes
Acid Mantle of Skin: skin secretions (sweat and sebum) make epidermal surface acidic, which inhibits bacterial growth, also contain various bactericidal chamicals
Intact mucous membranes: Form mechanical barrier that prevents entry of pathogens
Cilia: propel debris-laden mucus away from nasal cavity and lower respiratory passages
Gastric Juice: contains concentrated hydrochloric acid and protein-digesting enzymes that destroy pathogens in stomach
Acid Mantle of Vagina: Inhibits growth of most bacteria and fungi in female reproductive tract
Nasal Hairs: filter and trap microoganisms in nasal passages
Mucus: traps microoganisms in respiratory and digestive tracts
Lacrimal Secretion (tears); Saliva: continuously lubricate and cleanse eyes (tears) and oral cavity (saliva); contain lysozyme, an enzyme that destroys microorganisms
Urine: normally acid pH inhibits bacterial growth; cleanses the lower urinary tract as it flushes from the body
Second Line of Defense: antimicrobial proteins, phagocytes, and other cells
inhibit spread of invaders
Inflammation most important mechanism
many second-line cells have pattern recognition receptors that recognize and bind tightly to structures on microbes, disarming them before they do harm
Internal Defenses: necessary is microorganisms invade deeper tissues
Phagocytes
Phagocytes: white blood cells that ingest and digest (eat) foreign invaders
Neutrophils: most abundant phagocytes, but die fighting; become phagocytic on exposure to infectious material
Macrophages: develop from monocytes and are chief phagocytic cells; most robust phagocytic cell
Natural killer (NK) cells
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 “self” cell-surface receptors
Kill by inducing apoptosis in cancer cells and virus-infected cells
Secrete potent chemicals that enhance inflammatory response
Inflammatory response (macrophages, mast cells, WBCs, and inflammatory chemicals)
Inflammation is triggered whenever body tissues are injured
Injuries can be due to trauma, heat, irritating chemicals, or infections by microorganisms
Benefits of inflammation
Disposes of cell debris and pathogens
Alerts adaptive immune system
Prevents spread of damaging agents
Sets the stage for repair
Four cardinal signs of acute inflammation
Redness, Heat, Swelling, Pain
Sometimes a fifth sign, impairment of function, is seen if movement or use of area is hampered
Stages of Inflammation
Vsodilation and increased vascular permeability
Phagocyte mobilization
Neutrophils flood area first; macrophages follow
If inflammation is due to pathogens, complement is activated; adaptive immunity elements arrive
Inflammatory chemical release
Chemicals are released into ECF by injured tissues or immune cells
Other inflammatory mediators besides histamine
Kinins, prostaglandins (PGs), cytokines and if pathogens are involved, complement
3 more items...
Antimicrobial proteins (interferons and complement proteins)
Fever
Nonspecific
Do have specific pathway for certain substances
Adaptive Immune Defense
Third Line of Defense attacks particular foreign substances
Takes longer than innate
Specific
Humoral Immunity: B cells
Cellular Immunity: T cells
Adaptive immune system is a specific defensive system that eliminates almost any pathogen or abnormal cell in body
Characteristics of adaptive immunity
It is specific: recognizes and targets specific antigens
It is systemic: not restricted to initial site
It has memory: mounts an even stronger attack to “known” antigens (second and subsequent exposures)
Two main branches of adaptive system
Cellular (cell-mediated) immunity
Lymphocytes act against target cell
Directly—by killing infected cells
Indirectly—by releasing chemicals that enhance inflammatory response; or activating other lymphocytes or macrophages
Humoral (antibody-mediated) immunity
Bind temporarily to target cell
Mark for destruction
Antibodies, produced by lymphocytes, circulate freely in body fluids
Innate and Adaptive Immune Defenses
Innate responses release proteins that alert cells of adaptive system to foreign molecules
Both release and recognize many of the same defensive molecules
Humoral Response and Cellular Response
Two main branches of adaptive system
Cellular (cell-mediated) immunity
Lymphocytes act against target cell
Directly—by killing infected cells
Indirectly—by releasing chemicals that enhance inflammatory response; or activating other lymphocytes or macrophages
Humoral (antibody-mediated) immunity
Bind temporarily to target cell
Mark for destruction
Antibodies, produced by lymphocytes, circulate freely in body fluids
Antigens and Antibodies
Antigens: substances that can mobilize adaptive defenses and provoke an immune response
Mast are large, complex molecules not normally found in body (nonself)
Characteristics of antigens
Can be a complete antigen or hapten (incomplete)
Contain antigentic determinants
Can be a self-antigen
Targets of all adaptive immune responses
Self-Antigens : MHC Proteins
Self-antigens: all cells are covered with variety of proteins located on surface that are not antigenic to self, but may be antigenic to others in transfusions or grafts
One set of important self-proteins are group of glycoproteins called MHC proteins
Coded by genes of major histocompatibility complex (MHC) and unique to each individual
Contain groove that can hold piece of self-antigen or foreign antigen
T lymphocytes can recognize only antigens that are presented on MHC proteins
Antibodies—also called Immunoglobulins (Igs)—are proteins secreted by plasma cells
Basic antibody structure
Overall T- or Y-shaped antibody monomer consists of four looping polypeptide chains linked by disulfide bonds
Four chains consist of:
Two identical heavy (H) chains with hinge region at “middles”
Two identical light (L) chains
Variable (V) regions at one end of each arm combine to form two identical antigen-binding sites
Stems make up constant (C) regions
Grouped into one of five Ig classes
Five major classes: IgM, IgA, IgD, IgG, IgE
Capable of binding specifically with antigen detected by B cells
Antibody targets and functions
Antibodies do not destroy antigens; they inactivate and tag them
Form antigen-antibody(immune) response
Defensive mechanisms used by antibodies
Complement fixation and activation
Main antibody defense against cellular antigens (bacteria, mismatched RBCs)
When several antibodies are bound close together on same antigen, complement-binding sites on their stem regions are aligned
Precipitation
Soluble molecules (instead of cells) are cross-linked into complexes
Complexes precipitate out of solution
Precipated complexes are easier for phagocytes to engulf
Agglutination
Allows for antigen-antibody complexes to become cross-linked into large lattice-like clumps
Neutralization
Simplest, but one of most important defensive mechanism
Antibodies block specific sites on viruses or bacterial exotoxins
Prevent antigens from binding to receptors on tissue cells
Antigen-antibody complexes undergo phagocytosis
Artificial vs. Naturally acquired immunity
Artificially Acquired Immunity
In active humoral immunity it is formed in response to a vaccine of dead or attenuated pathogens
In passive humoral immunity it is the injection of serum
Naturally Acquired Immunity
In passive humoral immunity it is the antibodies delievered to a fetus via placenta or to an infant through milk
In active humoral immunity it is fromed in response to actual bacterial or viral infections
Passive vs. Active Immunity
Active humoral immunity occurs when B cells encounter antigens and produce specific antibodies against them
Two types of active humoral immunity
Artificially acquired: formed in response to vaccine of dead or attenuated pathogens
Naturally acquired: formed in response to actual bacterial or viral infection
Passive humoral immunity occurs when ready-made antibodies are introduced into body
Protection ends when antibodies degrade
Two types of passive humoral immunity
Naturally acquired: antibodies delivered to fetus via placenta or to infant through milk
Artificially acquired: injection of serum, such as gamma globulin
Protection immediate but ends when antibodies naturally degrade in body
B cells are not challenged by antigens; Immunological memory does not occur
Cells involved in the Immune System and their Functions
Cells involved
Phagocytes
Phagocytes: white blood cells that ingest and digest (eat) foreign invaders
Neutrophils: most abundant phagocytes, but die fighting; become phagocytic on exposure to infectious material
Macrophages: develop from monocytes and are chief phagocytic cells; most robust phagocytic cell
Natural killer (NK) cells
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 “self” cell-surface receptors
Kill by inducing apoptosis in cancer cells and virus-infected cells
Secrete potent chemicals that enhance inflammatory response
Inflammatory response (macrophages, mast cells, WBCs, and inflammatory chemicals)
Inflammation is triggered whenever body tissues are injured
Injuries can be due to trauma, heat, irritating chemicals, or infections by microorganisms
Benefits of inflammation
Disposes of cell debris and pathogens
Alerts adaptive immune system
Prevents spread of damaging agents
Sets the stage for repair
Four cardinal signs of acute inflammation
Redness, Heat, Swelling, Pain
Sometimes a fifth sign, impairment of function, is seen if movement or use of area is hampered
Stages of Inflammation
Vsodilation and increased vascular permeability
Phagocyte mobilization
Neutrophils flood area first; macrophages follow
If inflammation is due to pathogens, complement is activated; adaptive immunity elements arrive
Inflammatory chemical release
Chemicals are released into ECF by injured tissues or immune cells
Other inflammatory mediators besides histamine
Kinins, prostaglandins (PGs), cytokines and if pathogens are involved, complement
cause vasodilation of local arterioles
make capillaries leaky
many attract phagocytes to area
Two types of lymphocytes
B lymphocytes (B cells) - humoral immunity
T lymphocytes (T cells) - cullular immunity
Antigen-presenting cells (APCs)
Don't respond to specific antigens
Play essential auxillary roles in immunity
Engulf antigens and present fragments of antigens to T cells for recognition
3 Major types
Dendritic cells
Found in connective tissues and epidermis
Act as mobile sentinels of boundary tissues
Phagocytize pathogens that enter tissues, then enter lymphatics to present antigens to T cells in lymph node
Most effective antigen presenter known
Key link between innate and adaptive immunity
Macrophages
Widely distributed in connective tissues and lymphoid organs
Present antigens to T cells, which not only activates T cell, but also further activates macrophage
Activated macrophage becomes phagocytic killer
Also trigger powerful inflammatory responses and recruit additional defenses
B lymphocytes
Do not activate naive T cells
Present antigens to helper T cell to assist their own activation
Helper T cells
Activate both humoral and cellular arms
Once primed by APC presentation of antigen, helper T cells:
help activate B cells and other T cells
induce T and B cell proliferation
secrete cytokines that recruit other immune cells
Play central role in adaptive immune response
Without these there is no immune response
Activation of Cd* cells
CD8 cells require TH cell to become activated into destructive cytotoxic T cells
Cause dendritic cells to express co-stimulatory molecules required for CD8 cell activation
Activation of B cells
Helper T cells interact directly with B cells displaying antigen fragments bound to MHC II receptors
Stimulate B cells to divide more rapidly and begin antibody formation
Cytotoxic T cells
Activated TC cells circulate in blood and lymph and lymphoid organs in search of body cells displaying antigen they recognize
Activated Tc cells target
Virus-infected cells
Cells with intracellular bacteria or parasites
Cancer cells
Foreign cells (transfusions or transplants)
Directly attack and kill other cells
Cytotoxic T cells deliver lethal hit using two mechanisms
TC cell releases perforins and granzymes by exocytosis
stimulates apoptosis
TC cell binds specific membrane receptor on target cell and stimulates apoptosis
Regulatory T cells
Important in preventing autoimmune reactions
Disorders associated with the Immune System
Acquired immune deficiency syndrome (AIDS)
Human immunodeficiency virus (HIV) cripples immune system by interfering with activity of helper T cells
Characterized by severe weight loss, night sweats, and swollen lymph nodes
Opportunistic infections occur, including Pneumocystis pneumonia and Kaposi’s sarcoma
HIV is transmitted via body fluids: blood, semen, and vaginal secretions
HIV can enter the body via:
Blood transfusions; blood-contaminated needles; sexual intercourse and oral sex; mother to fetus
HIV destroys TH cells, thereby depressing cellular immunity
Symptoms begin when immune system collapses
No cure for AIDS found; four major classes of antivirals in combination help but can fail as virus becomes resistant
Autoimmune disease results when immune system loses ability to distinguish self from foreign
Hodgkin’s disease is an acquired immunodeficiency that causes cancer of B cells, which depresses lymph node cells and thus leads to immunodeficiency
Autoimmunity: production of autoantibodies and sensitized TC cells that destroys body tissues
Rheumatoid arthritis: destroys joints
Myasthenia gravis: impairs nerve-muscle connections
Multiple sclerosis: destroys white matter myelin
Graves’ disease: causes hyperthyroidism
Type 1 diabetes mellitus: destroys pancreatic cells
Systemic lupus erythematosus (SLE): affects multiple organs
Glomerulonephritis: damages kidney
Severe combined immunodeficiency (SCID) syndrome: genetic defect with marked deficit in B and T cells
Defective adenosine deaminase (ADA) enzyme allows accumulation of metabolites lethal to T cells; fatal if untreated
Treatment: bone marrow transplants
Hypersensitivities: immune responses to perceived (otherwise harmless) threat that cause tissue damage
Immunodeficiency: congenital or acquired conditions that impair function or production of immune cells or molecules
Immediate hypersensitivity
Initial contact with allergen is asymptomatic but sensitizes person
Activated IgE against antigen binds to mast cells and basophils
Also called acute (type I) hypersensitivities (allergies); begin in seconds after contact with allergen, antigen that causes allergic reaction
Later encounter with same allergen causes flood of histamine release from IgEs, resulting in induced inflammatory response
Histamines causes vasodilation and leakiness of the vessels, leading to symptoms of runny nose, itchy hives, or watery eyes
Asthma can occur if allergen is inhaled
Antihistamines are needed to control
Allergic reactions can be local or systemic
Systemic response is anaphylactic shock
Usually seen with injected allergens (example: bee sting)
Bronchioles constrict, making breathing difficult
asodilation results in low blood volume, which could cause circulatory collapse
Treatment: epinephrine