Lymphatic System Components of the lymphatic system Lymph

Lymphatic System § Functions of the lymphatic system § Return excess interstitial fluid to

Elephantiasis A condition in which parasites block lymphatic vessels, preventing the return of fluid

Lymphatic System § Lymphatic capillaries § Extra fluid enters these microscopic tubules § Differ

Lymphatic System § Lymph nodes § Bean-shaped structures § Filter lymph as it flows

Copyright © 2012 Pearson Education, Inc.

Body Defense Mechanisms § § § § The body’s defense system Three lines of

The Body’s Defense System § Targets of the body’s defense mechanisms § Pathogens §

Line of Defense § 1 st Line: barriers § Broad, external defense § “Walls

§ Adaptive Immunity: new phrasing for specific immunity § Innate Immune System: nonspecific defenses

1 st line: Physical Barriers • Non-specific defense • External barriers • skin –physically

Three Lines of Defense § First line of defense: Physical barriers § Skin §

Three Lines of Defense § First line of defense: Chemical barriers § Sweat and

Three Lines of Defense § First line of defense: Chemical barriers (cont. ) §

Three Lines of Defense § Second line of defense § § Defensive cells Defensive

2 nd Line of Defense Non-specific Inflammatory reaction §Four outward signs (redness, heat, swelling,

Three Lines of Defense § Defensive cells § Phagocytes (WBCs) that engulf pathogens §

Three Lines of Defense § Defensive cells (cont. ) § Natural killer (NK) cells

Three Lines of Defense § Defensive proteins § Interferons § Slow viral reproduction §

Three Lines of Defense § Interferons § Small proteins secreted by a cell infected

Three Lines of Defense § Complement system § Group of proteins that enhances both

Three Lines of Defense § Inflammatory response § Destroys invaders and helps repair and

Three Lines of Defense § Fever § An abnormally high body temperature § Caused

Three Lines of Defense § Third line of defense: Immune system § Has specific

3 rd Line of Defense - Specific Defense § Pathogens, cancer cells, or foreign

Different pathogen cause common infectious diseases Copyright © 2012 Pearson Education, Inc.

• Antibiotics kill pathogens inside the body • antibiotics cause pathogens to burst

§ Antibiotic resistance can cause medicines to become ineffective. – Some bacteria in a

Vaccines artificially produce acquired immunity. § Vaccines also control pathogens and disease. § given

• Vaccination provides acquired immunity. – stimulates a Antigens in a vaccine 1

Three Lines of Defense § Adaptive immune response § The body’s specific defenses §

Distinguishing Self from Nonself § MHC markers § Molecules found on our own cells

Distinguishing Self from Nonself § Antigens § Nonself substance or organism that triggers an

Distinguishing Self from Nonself § Lymphocytes § WBCs § Responsible for the specificity and

Distinguishing Self from Nonself § T cells § Recognize MHC self markers § T

Distinguishing Self from Nonself § T cells and B cells (cont. ) § B

Antibody-Mediated Responses and Cell-Mediated Responses § Antibody-mediated immune responses § Defend against antigens that

Antibody-Mediated Responses and Cell-Mediated Responses § Cell-mediated immune responses § Protect against cancer cells

Steps of the Adaptive Immune Response 1. Threat § Foreign organism or molecule (an

Steps of the Adaptive Immune Response 3. Alert § Macrophages present antigens to helper

Steps of the Adaptive Immune Response 4. Alarm § Helper T cells activate appropriate

Steps of the Adaptive Immune Response 5. Building specific defenses § B cells form

Steps of the Adaptive Immune Response 6. Defense: The antibody-mediated response § Antibodies specific

Steps of the Adaptive Immune Response § Immunoglobulins § Five classes of antibodies, each

Steps of the Adaptive Immune Response 6. Defense: The cell-mediated response § An effector

Steps of the Adaptive Immune Response 7. Continued surveillance § Immunological memory allows for

Steps of the Adaptive Immune Response 8. Withdrawal of forces § Suppressor T cells

Immunity § Active § Body creates an immune response after being exposed to a

Active and Passive Immunity § Active immunity § The body produces memory B cells

Active and Passive Immunity § Passive immunity § Results when a person receives antibodies

Monoclonal Antibodies § Monoclonal antibodies § A group of identical antibodies that bind to

Problems of the Immune System § Autoimmune disorders § Occur when the immune system

Problems of the Immune System § Allergies § Overreaction by the immune system to

Problems of the Immune System § Steps in an allergic reaction § During the

Problems of the Immune System § Anaphylactic shock § Extreme allergic reaction that can

Problems of the Immune System § Allergens can be identified by injecting small amounts

Slides: 73

Download presentation

Lymphatic System § Components of the lymphatic system § Lymph § Fluid identical to interstitial fluid § Lymphatic vessels § Vessels through which lymph flows § Have one-way valves to prevent backflow § Lymphoid tissues and organs Copyright © 2012 Pearson Education, Inc.

Lymphatic System § Functions of the lymphatic system § Return excess interstitial fluid to the bloodstream § Transport products of fat digestion from the small intestine to the bloodstream § Defend the body against disease-causing organisms and abnormal cells Copyright © 2012 Pearson Education, Inc.

Elephantiasis A condition in which parasites block lymphatic vessels, preventing the return of fluid to blood Results in massive swelling, darkening, and thickening of the skin in the affected area Copyright © 2012 Pearson Education, Inc.

Lymphatic System § Lymphatic capillaries § Extra fluid enters these microscopic tubules § Differ from blood capillaries § End blindly § More permeable § Drain into larger lymphatic vessels § Lymph eventually enters ducts that join with large veins at the base of the neck Copyright © 2012 Pearson Education, Inc.

Lymphatic System § Lymph nodes § Bean-shaped structures § Filter lymph as it flows through them § Contain macrophages and lymphocytes that actively defend against disease-causing organisms Copyright © 2012 Pearson Education, Inc.

Body Defense Mechanisms § § § § The body’s defense system Three lines of defense Distinguishing self from nonself Antibody-mediated responses and cell-mediated responses Steps of the adaptive immune response Active and passive immunity Monoclonal antibodies Problems of the immune system Copyright © 2012 Pearson Education, Inc.

The Body’s Defense System § Targets of the body’s defense mechanisms § Pathogens § Disease-causing bacteria, viruses, protozoans, fungi, parasitic worms, prions § Cancer cells § Once normal body cells whose genetic changes cause unregulated cell division Copyright © 2012 Pearson Education, Inc.

Line of Defense § 1 st Line: barriers § Broad, external defense § “Walls and Moats” § skin & mucus membranes § 2 nd Line: Nonspecific patrol § Broad, internal defense § “Patrolling soldiers” § phagocytes eating WBC’s § 3 rd Line: Immune System § Specific, acquired immunity § Elite trained units § lymphocyte WBCs & antibodies § B & T cells Copyright © 2012 Pearson Education, Inc.

1 st line: Physical Barriers • Non-specific defense • External barriers • skin –physically blocks pathogens • mucus membranes- traps particles in nose and throat • excretions • sweat • tears • mucus • stomach acids • saliva (“lick your wounds”) Copyright © 2012 Pearson Education, Inc. Lining of trachea: ciliated cells & mucus secreting cells

Three Lines of Defense § First line of defense: Physical barriers § Skin § Nearly impenetrable § Waterproof § Resistant to most toxins and enzymes of invading organisms § Mucous membranes § Line the respiratory and digestive tracts § Sticky mucus traps microbes Copyright © 2012 Pearson Education, Inc.

Three Lines of Defense § First line of defense: Chemical barriers § Sweat and oil glands of the skin § Produce chemicals that slow or prevent growth of bacteria § Lining of the stomach § Produces hydrochloric acid and proteindigesting enzymes that destroy pathogens Copyright © 2012 Pearson Education, Inc.

Three Lines of Defense § First line of defense: Chemical barriers (cont. ) § Urine § Slows bacterial growth with acidity § (Also washes microbes from urethra) § Saliva and tears § Contain lysozyme, an enzyme that kills bacteria Copyright © 2012 Pearson Education, Inc.

2 nd Line of Defense Non-specific Inflammatory reaction §Four outward signs (redness, heat, swelling, & pain) §Histamine is released which cause capillaries to become enlarged §and more permeable §(causes redness, §swelling, pain) White Blood cells Non-specific (macrophage) Copyright © 2012 Pearson Education, Inc.

Three Lines of Defense § Defensive cells § Phagocytes (WBCs) that engulf pathogens § Neutrophils § Arrive first § Macrophages § Develop from monocytes that leave the circulatory system § Eosinophils § Attack pathogens that are too large for phagocytosis, such as parasitic worms Copyright © 2012 Pearson Education, Inc.

Three Lines of Defense § Defensive cells (cont. ) § Natural killer (NK) cells § Also a type of WBC § Search out abnormal cells, including cancer cells, and kill them Copyright © 2012 Pearson Education, Inc.

Three Lines of Defense § Interferons § Small proteins secreted by a cell infected by a virus § Attract macrophages and natural killer cells that destroy infected cells § Stimulate neighboring cells to make proteins that prevent the viruses from replicating in those cells Copyright © 2012 Pearson Education, Inc.

Three Lines of Defense § Complement system § Group of proteins that enhances both nonspecific and specific defense mechanisms § Destroy pathogens § Enhance phagocytosis § Stimulate inflammation Copyright © 2012 Pearson Education, Inc.

Three Lines of Defense § Fever § An abnormally high body temperature § Caused by pyrogens § Chemicals that reset the brain’s thermostat to a higher temperature § A mild or moderate fever helps fight bacterial infection § A very high fever (over 105 F or 40. 6 C) is dangerous Copyright © 2012 Pearson Education, Inc.

Three Lines of Defense § Third line of defense: Immune system § Has specific responses and memory § Organs of the lymphatic system are important components § Defined by its function § Recognize and destroy specific pathogens or foreign molecules Copyright © 2012 Pearson Education, Inc.

3 rd Line of Defense - Specific Defense § Pathogens, cancer cells, or foreign cells have protein markers on surface (antigens) that activate the immune system because foreign to body Types of White Blood Cells - all made in the bone marrow - All called in after the non-specific WBCs § B lymphocyte cells (mature in bone marrow) § produce antibodies that combine with antigens and target particular pathogens § Produce memory B cells § T lymphocyte cells (mature in thymus gland) § directly destroy infected cells § produce cytotoxic T cells, helper T cells, and memory T cells Copyright © 2012 Pearson Education, Inc.

• Antibiotics kill pathogens inside the body • antibiotics cause pathogens to burst • target on specific bacterium or fungus • not effective against viruses • antibiotic resistance issues Antibiotics have killed the bottom cell by weakening its cell wall and causing it to burst. (colored TEM; magnification 55, 000 X Aimee Copeland – Ziplining Copyright © 2012 Pearson Education, Inc.

§ Antibiotic resistance can cause medicines to become ineffective. – Some bacteria in a population have genes that make them immune to antibiotics. – These bacteria spread the gene, making the antibiotics useless. A bacterium carries genes for antibiotic resistance on a plasmid. A copy of the plasmid is transferred through conjugation. Resistance is quickly spread through many bacteria. Copyright © 2012 Pearson Education, Inc.

Vaccines artificially produce acquired immunity. § Vaccines also control pathogens and disease. § given to prevent illness § contain the antigen of a weakened pathogen Copyright © 2012 Pearson Education, Inc.

• Vaccination provides acquired immunity. – stimulates a Antigens in a vaccine 1 trigger an immune specific immune response, and memory B cells are made. response memory B cell is – causes memory 2 Astimulated when the real pathogen binds to it. cells to be produced – allows immune B cell quickly system to respond 3 The activates and makes antibodies that fight the quickly to infection pathogens before you get – has such a fast response, a person will not get sick Copyright © 2012 Pearson Education, Inc. sick.

Three Lines of Defense § Adaptive immune response § The body’s specific defenses § Important characteristics § Specificity § Directed at a specific pathogen § Memory § Remembers the pathogen and attacks it so quickly that illness does not result upon second exposure Copyright © 2012 Pearson Education, Inc.

Distinguishing Self from Nonself § MHC markers § Molecules found on our own cells that label cells as “self” § Named for major histocompatibility genes that code for them § Used by the immune system to distinguish cells of your body from foreign invaders Copyright © 2012 Pearson Education, Inc.

Distinguishing Self from Nonself § Antigens § Nonself substance or organism that triggers an immune response § Usually large molecules, such as proteins, polysaccharides, or nucleic acids § Often found on surface of invader Copyright © 2012 Pearson Education, Inc.

Distinguishing Self from Nonself § Lymphocytes § WBCs § Responsible for the specificity and memory of the adaptive immune response § B lymphocytes (B cells) § Form and mature in bone marrow § T lymphocytes (T cells) § Form in bone marrow and mature in thymus gland Copyright © 2012 Pearson Education, Inc.

Distinguishing Self from Nonself § T cells § Recognize MHC self markers § T cells and B cells § Programmed to recognize one particular type of antigen § Specificity results from each cell developing its own particular receptors on its surface § When an antigen fits into receptors, then the body targets that particular antigen Copyright © 2012 Pearson Education, Inc.

Distinguishing Self from Nonself § T cells and B cells (cont. ) § B cells and T cells that respond to a particular antigen divide repeatedly, forming two cell lines § Effector cells § Short-lived cells that attack the invader § Memory cells § Long-lived cells that remember the invader and mount a quick response when it is next encountered Copyright © 2012 Pearson Education, Inc.

Antibody-Mediated Responses and Cell-Mediated Responses § Antibody-mediated immune responses § Defend against antigens that are free in body fluids, including toxins or extracellular pathogens § Effector B cells (plasma cells) use antibodies (Y-shaped proteins) to neutralize the antigen Copyright © 2012 Pearson Education, Inc.

Antibody-Mediated Responses and Cell-Mediated Responses § Cell-mediated immune responses § Protect against cancer cells and body cells that have become infected with viruses or other pathogens § Cytotoxic T cells cause cancer cells and infected body cells to burst Copyright © 2012 Pearson Education, Inc.

Steps of the Adaptive Immune Response 1. Threat § Foreign organism or molecule (an antigen) enters the body 2. Detection § Macrophage detects foreign organism or molecule and engulfs it Copyright © 2012 Pearson Education, Inc.

Steps of the Adaptive Immune Response 3. Alert § Macrophages present antigens to helper T cells § Macrophages are antigen-presenting cells § Helper T cells are the main switch for the adaptive immune response Copyright © 2012 Pearson Education, Inc.

Steps of the Adaptive Immune Response 4. Alarm § Helper T cells activate appropriate B cells and T cells to destroy the specific antigen § When activated, these cells divide to form clones of cells designed to eliminate the specific antigen from the body § Clonal selection is critical to the adaptive immune response Copyright © 2012 Pearson Education, Inc.

Steps of the Adaptive Immune Response 5. Building specific defenses § B cells form plasma cells that secrete antibodies into the bloodstream that bind to antigens § T cells form cytotoxic T cells that attack Copyright © 2012 Pearson Education, Inc.

Steps of the Adaptive Immune Response 6. Defense: The antibody-mediated response § Antibodies specific to the antigen eliminate the antigen § Precipitation § Lysis (bursting) § Attraction of phagocytes § Neutralization Copyright © 2012 Pearson Education, Inc.

Steps of the Adaptive Immune Response § Immunoglobulins § Five classes of antibodies, each with a special role to play in protecting against invaders § Ig. G § Ig. M § Ig. E § Ig. A § Ig. D Copyright © 2012 Pearson Education, Inc.

Steps of the Adaptive Immune Response 6. Defense: The cell-mediated response § An effector cytotoxic T cell releases perforins, which cause holes to form in cells with the particular antigen Copyright © 2012 Pearson Education, Inc.

Steps of the Adaptive Immune Response 7. Continued surveillance § Immunological memory allows for a more rapid response on subsequent exposure to the antigen § Primary response § Occurs during body’s first encounter with a particular antigen § Antibody concentration rises slowly § Secondary response § Occurs during subsequent encounter with that antigen § Strong and swift due to the large number of memory cells programmed to respond to that particular antigen Copyright © 2012 Pearson Education, Inc.

Immunity § Active § Body creates an immune response after being exposed to a pathogen or a vaccine § Memory cells are produced so this immunity lasts (sometimes even a lifetime) § Passive § Antibodies in breast milk or shots of antibodies provide a temporary immune response Copyright © 2012 Pearson Education, Inc.

Active and Passive Immunity § Active immunity § The body produces memory B cells and T cells following exposure to an antigen § Occurs naturally whenever a person gets an infection § Can also occur through vaccination § Introduction of a harmless form of an antigen into the body to stimulate immune responses § Long-lived because memory cells are produced Copyright © 2012 Pearson Education, Inc.

Active and Passive Immunity § Passive immunity § Results when a person receives antibodies that were produced by another person or animal § Short-lived because the recipient’s body was not stimulated to produce memory cells Copyright © 2012 Pearson Education, Inc.

Monoclonal Antibodies § Monoclonal antibodies § A group of identical antibodies that bind to one specific antigen § Used in research, clinical diagnosis, and disease treatment Copyright © 2012 Pearson Education, Inc.

Problems of the Immune System § Autoimmune disorders § Occur when the immune system fails to distinguish between self and nonself and attacks tissues or organs of the body § Classification § Organ-specific § Usually caused by problematic T cells § Example: Hashimoto’s thyroiditis § Non-organ-specific § Usually caused by problematic B cells § Example: systemic lupus erythematosus Copyright © 2012 Pearson Education, Inc.

Problems of the Immune System § Allergies § Overreaction by the immune system to an antigen § The antigen is usually harmless and is called an allergen § Example: hay fever (allergic rhinitis) Copyright © 2012 Pearson Education, Inc.

Problems of the Immune System § Steps in an allergic reaction § During the first exposure: § Allergens cause plasma cells to release class Ig. E antibodies § Ig. E antibodies bind to mast cells or basophils § On subsequent exposures: § Allergen combines with Ig. E attached to mast cells and causes release of histamine § Histamine causes redness, swelling, itching, and other symptoms of an allergic response Copyright © 2012 Pearson Education, Inc.

Problems of the Immune System § Anaphylactic shock § Extreme allergic reaction that can be fatal § Can cause pooling of blood in capillaries, which makes breathing difficult § Common triggers § Insect stings § Medications (penicillin) § Foods (shellfish, peanuts) Copyright © 2012 Pearson Education, Inc.

Problems of the Immune System § Allergens can be identified by injecting small amounts of suspected antigens and monitoring skin response § Treatments § Antihistamines § Block the effects of histamine § Allergy shots § Inject increasing amounts of a known allergen in an effort to desensitize the person to the offending allergen Copyright © 2012 Pearson Education, Inc.