multiple choice - Lymphatic System
Capillaries and Recirculate
E.
Stem Region
E.
Nonspecific Resistance
Guards equally against a broad range of pathogens; effectiveness does not depend on prior exposure (first and second lines of defense)
Helper T Cells
Help promote cytotoxic T cell and B cell action and nonspecific resistance
Neutrophils
Highly mobile phagocytes that water in connective tissue killing bacteria; Create a killing zone by degranulation and respiratory burst
Interleukin 2
IL-2 is a key growth factor, acting on cells that release it and other T cells: Encourages activated T cells to divide rapidly, used therapeutically to treat melanoma and kidney cancers, and other cytokines amplify and regulate innate and adaptive responses.
Secondary Lymphatic Organs
Immunocompetent cells populate these tissues
Humoral Immunity
Indirect method of specific immunity in which B lymphocytes produce antibodies that bind to antigens and tag them for destruction by other means
Regulatory T Cells
Inhibit multiplication and cytokine secretion by other T cells; Limit immune response
Heparin
Inhibits the formation of clots; Anticoagulant secreted by basophils
Passive Artificially Acquired
Injection of serum, such as gamma globulin and protection is immediate but ends when antibodies naturally degrade in the body.
Natural Killer (NK) Cells
Large granular lymphocytes, target cells that lack "self" cell-surface receptors, induce apoptosis in cancer cells and virus- infected cells, and secrete potent chemicals that enhance the inflammatory response.
Natural Killer Cells
Large lymphocytes that attack and destroy bacteria, transplanted tissue, host cells infected with viruses or have turned cancerous; Responsible for immune surveillance
IgM
Largest antibodies; Secreted in primary immune response, agglutination, and complement fixation
Thoracic Duct
Left collecting duct that empties into the left subclavian vein
Diapedesis (Emigration)
Leukocytes squeeze through gaps in the endothelial cells and enter tissue fluid; Occurs during inflammation
Inflammation
Local defensive response to tissue injury of any kind, including trauma and infection
3 Liters
Lost to tissues every 24 hours returned to the bloodstream.
Immunoglobulin
A defensive gamma globulin found in the blood-plasma, tissue fluids, body secretions, and some leukocyte membranes; Antibody
Cellular Immunity
A form of specific defense in which the T lymphocytes directly attack and destroy diseased or foreign cells, and the immune system remembers the antigens and prevents them from causing disease in the future
Complement System
A group of 30 or more globular proteins that make powerful contributions to both nonspecific resistance and specific immunity
IgM
A pentamer; first antibody released, potent agglutinating agent, readily fixes and activates complement, largest, medics of the first responders.
Red Bone Marrow and place where T and B Cells are born at
A.
9) Antibodies that act against a particular foreign substance are released by ________. A) T lymphocytes B) plasma cells C) lymph nodes D) medullary cords
B
Generating Antibody Diversity
Billions of antibodies result from somatic recombination of gene segments, hypervariable regions of some genes increase antibody variation through somatic mutations, and each plasma cell can switch the type of H chain produced, making an antibody of a different class.
Internal Defenses: Cells and Chemicals
Necessary if microorganisms invade deeper tissues by: • Phagocytes • Natural killer (NK) cells • Inflammatory response (macrophages, mast cells, WBCs, and inflammatory chemicals) • Antimicrobial proteins (interferons and complement proteins) • Fever
Margination
Neutrophils cling to capillary wall, clinging of phagocytic cells to inner wall of capillaries.
Leukocytes
Neutrophils enter blood from bone marrow.
Diapedesis
Neutrophils flatten and squeeze out of capillaries, phagocytes squeeze through the capillary endothelium.
Chemotaxis
Neutrophils follow chemical trail, white blood cells migrate to the site of tissue damage.
Respiratory Burst
Neutrophils rapidly absorb oxygen and creates toxic chemicals
Phagocyte Mobilization
Neutrophils, then phagocytes flood to inflamed sites.
Second Line of Defense
Nonspecific defense mechanisms; Leukocytes and macrophages, antimicrobial proteins (lysozymes), immune surveillance, inflammation, stomach acid, and fever
Antibodies of the Humoral Response
The simplest ammunition of the immune response Targets: Bacteria and molecules in extracellular environments (body secretions, tissue fluid, blood, and lymph).
Innate Defense System
Two lines of defense • First line of defense is external body membranes (skin and mucosae) • Second line of defense is antimicrobial proteins, phagocytes, and other cells by: Inhibit spread of invaders Inflammation is its most important mechanism
Self-Tolerance
Unresponsive to self antigens and property of lymphocytes that prevents them from attacking the body's own cells.
T Lymphocytes
(T Cells) Cell-Mediated Immunity in Thymus
Positive Selection
2% of T cells that pass the test multiply to form clones of identical T cells programmed to respond to a specific antigen
Fluid Recovery, Immunity, Lipid Absorption
3 Functions of the Lymphatic System
Palatine, Lingual, Pharyngeal (Adenoid)
3 Main Sets of Tonsils
Classical, Alternative, Lectin
3 Routes of Complement Activation
Lymph Nodes, Tonsils, Spleen
3 Secondary Lymphatic Organs
Recognition, Attack, Memory
3 Stages of Both Cellular and Humoral Immunity
Onset, Stadium, Defervescence
3 Stages of Fever
10) Lymph leaves a lymph node via ________. A) efferent lymphatic vessels B) afferent lymphatic vessels C) the cortical sinus D) the subscapular sinus
A
17) A ring of lymphoid tissue that appears as a swelling of the mucosa in the oral cavity is called a(n) ________. A) tonsil B) thymus C) Peyer's patch D) appendix
A
25) Functions of the lymphatic system include ________. A) transport of excess tissue fluid to the blood vascular system B) transport of red blood cells to the blood vascular system C) maintenance of blood pressure in the venous circulation D) excretion of excess dietary fat
A
MHC Proteins
Act as cell 'identification tags' that label every cell of your body as belonging to you
Leukotrienes
Activate and attract neutrophils and eosinophils
Lymphatic (Lymphoid) Tissue
Aggregations of lymphocytes in the connective tissues of mucous membranes and various organs
27) Which of the following is not a normal component of lymph? A) water B) plasma proteins C) red blood cells D) ions
C
Adherence of Phagocyte to Pathogen
Facilitated by opsonization—coating of pathogen by complement proteins or antibodies.
Pathogens
Environmental agents capable of producing disease
Lysozyme
Enzyme that destroys bacterial cell walls
Pyrogens
Fever producing agents
Bacterial Infection
Increase in Neutrophil
Adaptive Immune Response
Is specific, systemic, and has memory.
Cytotoxic T Cells
Killer T cells, carry out attack on enemy cells
Lacteals
Lymphatic vessels in the small intestine that absorb dietary lipids that are not absorbed by the blood capillaries
Gamma (γ)
Lymphocyte produce this.
White Pulp
Lymphocytes, macrophages surrounding small branches of splenic artery
External Barriers
Make up the first line of defense against pathogens
Other Type of T Cells
Regulatory T cells (TREG) and memory T cells.
Lymphatic Duct
Right collecting duct that empties into the right subclavian vein
Acid Mantle
Thin film of lactic acid from sweat which inhibits bacterial growth
Adaptive Defense System
Third line of defense attacks particular foreign substances by: Takes longer to react than the innate system and innate and adaptive defenses are deeply intertwined.
Lymphatic Vessels
Transport the lymph from interstial spaces (tissues) to the bloodstream
Alternate Pathway
Triggered when activated C3, B, D, and P interact on the surface of microorganisms.
Histamine
Vasodilator secreted by basophils
7) What effect does age have on the size of the thymus? A) The size of the thymus increases continuously from birth to death. B) The size of the thymus decreases continuously from birth to death. C) The thymus is not affected by age. D) The thymus initially increases in size and then decreases in size from adolescence through old age.
d
Antigen-Binding Site
A.
Bone Marrow and is immunocompetent with B Cells
C.
Tissue Injury
First Step in Inflammation
Antigen Challenge
First encounter between an antigen and a naive immunocompetent lymphocyte plus usually occurs in the spleen or a lymph node.
Active Humoral Immunity
Occurs when B cells encounter antigens and produce specific antibodies against them.
Palatine Tonsils
Pair of tonsils at posterior margin of oral cavity (most often infected) - visible to naked eye
Lymphatic System
Population of cells especially concentrated in the true organ system
Humoral Immunity
Provided by antibodies
Lymphocytes
T cells, B cells, and NK cells
2) Which of the following would not be classified as a lymphatic structure? A) pancreas B) spleen C) tonsils D) Peyer's patches of the intestine
a
18) Which is not a mucosa-associated lymphatic tissue? A) tonsil B) thymus C) Peyer's patch D) appendix
B
19) Peyer's patches are found in the ________. A) stomach B) small intestine C) large intestine D) spleen
B
Interferons, Complement System
Two Families of Antimicrobial Proteins
B Lymphocytes
(B Cells) Humoral Immunity in Red Bone
Interleukin 1
(IL-1) released by macrophages co-stimulates bound T cells to: • Release interleukin 2 (IL-2) • Synthesize more IL-2 receptors
Clonal Selection
1. B cell is activated when antigens bind to its surface receptors and cross-link them 2. Receptor-mediated endocytosis of cross- linked antigen-receptor complexes occurs 3. Stimulated B cell grows to form a clone of identical cells bearing the same antigen- specific receptors (T cells are usually required to help B cells achieve full activation)
Mechanisms of Autoimmune Diseases
1. Foreign antigens may resemble self-antigens and antibodies against the foreign antigen may cross- react with self-antigen. 2. New self-antigens may appear, generated by Gene mutations Changes in self-antigens by hapten attachment or as a result of infectious damage. 3. Release of novel self-antigens by trauma of a barrier (e.g., the blood-brain barrier)
Specificity, Memory
2 Characteristics that Distinguish Immunity from Nonspecific Resistance
Clonal Deletion, Anergy
2 Forms of Negative Selection
Red Bone Marrow, Thymus
2 Primary Lymphatic Organs
Cellular, Humoral
2 Types of Immunity
Mobilization, Containment, Tissue Cleanup
3 Stages of Inflammation
Redness, Swelling, Heat, Pain
4 Cardinal Signs of Inflammation
Cytotoxic, Helper, Regulatory, Memory
4 Classes of T Cells Involved in Cellular Immunity
Nodes, Tonsils, Thymus, Spleen
4 Major Lymphatic Organs
Inflammation, Immune Clearance, Phagocytosis, Cytolysis
4 Mechanisms of Action of Complement Proteins
NK Cells, T Cells, B Cells, Macrophages, Dendritic Cells, Reticular Cells
6 Types of Lymphatic Cells
26) The tonsils located at the base of the tongue are the ________. A) lingual tonsils B) palatine tonsils C) pharyngeal tonsils D) Peyer's tonsils
A
Human Immunodeficiency Virus (HIV)
AIDS is caused by this transmitted via body fluids—blood, semen, and vaginal secretions • HIV enters the body via • Blood transfusions • Blood-contaminated needles • Sexual intercourse and oral sex • HIV • Destroys TH cells • Depresses cell-mediated immunity
T Cell Activation
APCs (most often a dendritic cell) migrate to lymph nodes and other lymphoid tissues to present their antigens to T cells T cell activation is a two-step process: 1. Antigen binding 2. Co-stimulation
Reactivity
Ability to react with products of activated lymphocytes and antibodies released.
Immunogenicity
Ability to stimulate proliferation of specific lymphocytes and antibodies.
Immunocompetence
Able to recognize and bind to a specific antigen.
Immunocompetent
Able to recognize and respond to antigens
Destruction of Pathogens
Acidification and digestion by lysosomal enzymes by: • Respiratory burst • Release of cell-killing free radicals • Activation of additional enzymes • Oxidizing chemicals (e.g. H2O2) • Defensins (in neutrophils)
Margination
Adhesion of the leukocytes to the vessel wall; Occurs during inflammation
Skeletal Muscle Pump
Aids the flow of lymph
Immediate Hypersensitivity
Allergy
Fever
An abnormally elevation of body temperature; Stimulates neurons in the hypothalamus that raises the set point for body temperature
Leukocytosis
An increase in the number of white blood cells that are in circulation.
Without Co-Stimulation
Anergy occurs by T cells because: • Become tolerant to that antigen • Are unable to divide • Do not secrete cytokines
Agglutination
Antibodies bind the same determinant on more than one cell-bound antigen and cross-linked antigen-antibody complexes agglutinate. Example: clumping of mismatched blood cells
Classical Pathway
Antibodies bind to invading organisms and C1 binds to the antigen-antibody complexes (complement fixation).
Passive Naturally Acquired
Antibodies delivered to a fetus via the placenta or to infant through milk.
Antibody Targets
Antibodies inactivate and tag antigens, form antigen-antibody (immune) complexes, defensive mechanisms used by antibodies, neutralization and agglutination (the two most important), and precipitation and complement fixation.
Antigen
Any molecule that triggers an immune response; Complex molecule with structures unique to the individual
Dendritic Cells
Are able to obtain other cells' endogenous antigens by • Engulfing dying virus-infected or tumor cells • Importing antigens through temporary gap junctions with infected cells They then display the endogenous antigens on both class I and class II MHCs.
Immunocompetent T Cells
Are activated when their surface receptors bind to a recognized antigen (nonself) T cells must simultaneously recognize, nonself (the antigen), self (an MHC protein of a body cell).
Rheumatoid Arthritis
Autoimmune Disorder
11) By secreting hormones, the thymus causes what cells to become immunocompetent? A) basophils B) lymphocytes C) macrophages D) monocytes
B
12) Functions of the spleen include all of those below except ________. A) removal of old or defective blood cells from the blood B) crypts that trap bacteria C) storage of blood platelets D) storage of iron
B
13) When the lymphatics are blocked due to tumors, the result is ________. A) shrinkage of tissues distal to the blockage due to inadequate delivery of lymph B) severe localized edema distal to the blockage C) increased pressure in the lymphatics proximal to the blockage D) abnormally high lymph drainage from the distal region
B
15) Select the correct statement about lymphocytes. A) The two main types are T cells and macrophages. B) B cells produce plasma cells, which secrete antibodies into the blood. C) T cells are the precursors of B cells. D) T cells are the only form of lymphocyte found in lymphoid tissue.
B
Naive (Unexposed)
B and T cells are exported to lymph nodes, spleen, and other lymphoid organs.
Heavy Chain
B.
Thymus and is immunocompetent with T Cells
B.
Antibody Monomer
Basic structural unit of an antibody; Composed of four polypeptide chains: two larger heavy chains and two light chains
Clone Cells that do not become plasma cells
Become memory cells that provide immunological memory and mount an immediate response to future exposures of the same antigen.
Neutrophils
Become phagocytic on encountering infectious material in tissues.
Isografts
Between identical twins.
Allografts
Between individuals who are not identical twins.
Cytotoxic T Cells
Bind to a self-nonself complex and can destroy all infected or abnormal cells. Lethal Hit- Tc cell releases perforins and granzymes by exocytosis, perforins create pores through which granzymes enter the target cell, granzymes stimulate apoptosis • In some cases, TC cell binds with a Fas receptor on the target cell, and stimulates apoptosis
Reticular Cells
Branched stationary cells that contribute to the stroma of a lymphatic organ; Act as APCs in the thymus
Dendritic Cells
Branched, mobile APCs found in the epidermis, mucous membranes, and lymphatic organs; Alert immune system to pathogens that have breached their surface
16) Select the correct statement about lymphoid tissue. A) Once a lymphocyte enters the lymphoid tissue, it resides there permanently. B) Lymphoid macrophages secrete antibodies into the blood. C) Lymphoid tissue is predominantly reticular connective tissue. D) T lymphocytes act by ingesting foreign substances.
C
20) Lymph collecting or pooling from the lower extremities would first pool in the ________ before moving on up. A) thoracic duct B) inguinal nodes C) cisterna chyli D) azygos
C
Costimulation
The double checking of the T ell to see if it is really bound to a foreign antigen
Light Chain
C.
T Cell Activation: Antigen Binding
CD4 and CD8 cells bind to different classes of MHC proteins (MHC restriction), CD4 cells bind to antigen linked to class II MHC proteins of APCs, CD8 cells are activated by antigen fragments linked to class I MHC of APCs, TCR that recognizes the nonself-self complex is linked to multiple intracellular signaling pathways, other T cell surface proteins are involved in antigen binding (e.g., CD4 and CD8 help maintain coupling during antigen recognition), antigen binding stimulates the T cell, but co- stimulation is required before proliferation can occur.
Exercise
Can significantly increase lymphatic return
Subacute Hypersensitivities
Caused by IgM and IgG transferred via blood plasma or serum and slow onset (1-3 hours) and long duration (10-15 hours).
Low Pressure
Causes lymph to flow at a slower speed than venous blood
CD8
Cells become cytotoxic T cells (TC) that destroy cells harboring foreign antigens.
CD4
Cells become helper T cells (TH) when activated.
Antigenic Determinants
Certain parts of an entire antigen that are immunogenic and antibodies and lymphocyte receptors bind to them. Most naturally occurring antigens have numerous antigenic determinants that: Mobilize several different lymphocyte populations, form different kinds of antibodies against it, and large, chemically simple molecules (e.g.,plastics) have little or no immunogenicity.
Epitopes
Certain regions of an antigen molecule that stimulate immune responses
Cytokines
Class of chemicals that regulate inflammation and immunity
Lymph
Clear, colorless fluid, similar to plasma, but much less protein; recovered fluid of the lymphatic system
Opsonization
Coats microbial cells and serves as binding sites for phagocyte attachment (aids in phagocytosis by making the foreign cell more appetizing)
Monoclonal Antibodies
Commercially prepared pure antibody, produced by hybridomas, cell hybrids: fusion of a tumor cell and a B cell, proliferate indefinitely and have the ability to produce a single type of antibody; used in research, clinical testing, and cancer treatment.
Interferons (IFNs)
Complement proteins that attack microorganisms directly and hinder microorganisms' ability to reproduce, Viral-infected cells are activated to secrete this by enter neighboring cells, neighboring cells produce antiviral proteins that block viral reproduction and also activates macrophages and mobilizes NKs. Functions • Anti-viral • Reduce inflammation • Activate macrophages and mobilize NK cells • Genetically engineered IFNs for • Antiviral agents against hepatitis and genital warts virus • Multiple sclerosis treatment *They do not stimulate B cells to produce antibodies.*
Immunodeficiencies
Congenital and acquired conditions that cause immune cells, phagocytes, or complement to behave abnormally.
14) Select the correct statement about lymph transport. A) Under normal conditions, lymph vessels are very high-pressure conduits. B) Lymph transport is faster than that occurring in veins. C) Lymph transport is only necessary when illness causes tissue swelling. D) Lymph transport depends on the movement of adjacent tissues, such as skeletal muscles.
D
21) What is a bubo? A) a wall in a lymph node B) a lobe of the spleen C) an infected Peyer's patch D) an infected lymph node
D
22) What is the function of a Hassall's corpuscle? A) It increases the surface area of the thymic cortex. B) It assists in the production of lymphocytes. C) It forms the blood-thymus barrier. D) It has no known significant function.
D
23) Particularly large clusters of lymph nodes occur in all of the following locations except the ________. A) inguinal region B) cervical region C) axillary region D) lower extremities
D
24) Digestive tract-associated lymphatic tissue includes all of the following except ________. A) Peyer's patches B) palatine tonsils C) lingual tonsils D) islets of Langerhans
D
28) A sentinel node is ________. A) a lymph node found in the intestinal lamina propria B) the first node at the junction of all the lumbar trunks C) a small node in the spleen D) the first node to receive lymph from an area suspected to be cancerous
D
Hinge Region
D.
Lymph Nodes and help with clone selection and with both B and T cells
D.
Regulatory T (TReg) Cells
Dampen the immune response by direct contact or by inhibitory cytokines and important in preventing autoimmune reactions.
Tonsilar Crypts
Deep pits of the tonsils lined with lymphatic nodules where pathogens enter in and encounter lymphocytes
Granzymes
Degrading enzymes that induce apoptosis
Chyle
Delivered to blood via lymphatic system.
Peyer Patches
Dense clusters in the ileum, the distal portion of the small intestine
Lymphatic Nodules
Dense masses of lymphocytes and macrophages that congregate in response to pathogens
Phagocytes: Macrophages
Develop from monocytes to become the chief phagocytic cells Free macrophages wander through tissue spaces • E.g., alveolar macrophages Fixed macrophages are permanent residents of some organs • E.g., Kupffer cells (liver) and microglia (brain)
Macrophages
Develop from monocytes; Phagocytize tissue debris, dead neutrophils, bacteria, and other foreign matter; Antigen Presenting Cells
Class I MHC Proteins
Displayed by all cells except RBCs, bind with fragment of a protein synthesized in the cell (endogenous antigen), endogenous antigen is a self-antigen in a normal cell; a nonself antigen in an infected or abnormal cell, informs cytotoxic T cells of the presence of microorganisms hiding in cells (cytotoxic T cells ignore displayed self-antigens).
Antigen-Presenting Cells (APCs)
Do not respond to specific antigens and play essential auxiliary roles in immunity.
Class II MHC Proteins
Dsplayed by APCs (dendritic cells, macrophages and B cells), bind with fragments of exogenous antigens that have been engulfed and broken down in a phagolysosome, and recognized by helper T cells.
Complement Activation
Each pathway involves activation of proteins in an orderly sequence, each step catalyzes the next, both pathways converge on C3, which cleaves into C3a and C3b, enhances inflammation, promotes phagocytosis, causes cell lysis, C3b initiates formation of a membrane attack complex (MAC), MAC causes cell lysis by inducing a massive influx of water, C3b also causes opsonization, and C3a causes inflammation.
Monocytes
Emigrate from the blood into the connective tissue and transform into macrophages
Antigen-Presenting Cells (APCs)
Engulf antigens, present fragments of antigens to be recognized by T cells. Major types: Dendritic cells in connective tissues and epidermis, macrophages in connective tissues and lymphoid, organs, and B cells.
T Cells that are Activated
Enlarge, proliferate, and form clones plus differentiate and perform functions according to their T cell class.
1) Peyer's patches are clusters of lymphoid tissue found primarily in the large intestine.
FALSE
3) Lymph always flows away from the heart
FALSE
All lymphoid organs develop from mesoderm
FALSE
All the lymphoid organs are well developed before birth
FALSE
The cisterna chyli collects lymph from the lumbar trunks draining the upper limbs and from the intestinal trunk draining the digestive organs
FALSE
The largest lymphatic vessels are called lacteals
FALSE
The thymus lacks T cells
FALSE
Lacteal
Fats absorbed in lymph capillaries.
Beta (β) Interferon
Fibroblasts produce this.
MALT
Found in digestive layers; Associated with diffuse lymphatic tissue
Class II MHC Proteins
Found on certain cells in the immune response, antigen-presenting cells.
Class I MHC Proteins
Found on virtually all body cells (except RBC)
Xenografts
From another animal species.
Autografts
From one body site to another in the same person.
Immunoglobulins
Gamma globulin portion of blood, protein secreted by plasma cells and capable of binding specifically with antigen detected by B cells.
T Lymphocytes
Lymphatic cells that mature in the thymus and become immunocompetent
B Lymphocytes
Lymphatic cells that when activated causes proliferation and differentiation into plasma cells that produce antibodies
Red Bone Marrow
Lymphatic organ involved in hemopoiesis and immunity
Diffuse Lymphatic Tissue
Lymphocytes are scattered, rather than densely clustered in mucous membranes and connective tissue of many organs; Found in respiratory, digestive mucosa, urinary, and reproductive tracts; Associated with MALT
Antigen Receptor Diversity
Lymphocytes make up to a billion different types of antigen receptors is coded for by ~25,000 genes, gene segments are shuffled by somatic recombination, genes determine which foreign substances the immune system will recognize and resist.
Degranulation
Lysosomes discharge contents into tissue fluid
Toll-Like Receptors (TLR)
Macrophages and epithelial cells of boundary tissues bear this and recognize specific classes of infecting microbes by activated this trigger the release of cytokines that promote inflammation.
Present Antigen and Activate T Cells
Macrophages mostly remain fixed in the lymphoid organs dendritic cells internalize pathogens and enter lymphatics to present the antigens to T cells in lymphoid organs.
Immune Clearance
Macrophages of the liver and spleen strip off and destroy the Ag-Ab complexes leaving RBCs unharmed (clearing foreign antigens from the bloodstream)
Complement Fixation and Activation
Main antibody defense against cellular antigens, several antibodies bind close together on a cellular antigen, their complement-binding sites trigger complement fixation into the cell's surface, complement triggers cell lysis, activated complement functions, amplifies the inflammatory response, opsonization, and enlists more and more defensive elements.
B Cells
Mature in red bone marrow, Self-reactive B cells, are eliminated by apoptosis (clonal deletion) or undergo receptor editing - rearrangement of their receptors are inactivated (anergy) if they escape from the bone marrow, involved in adaptive immunity.
T Cells
Mature in the thymus under negative and positive selection pressures, positive selection, selects T cells capable of binding to self-MHC proteins (MHC restriction), negative selection, prompts apoptosis of T cells that bind to self-antigens displayed by self-MHC, ensures self-tolerance.
Cytolysis
Mechanism of complement system that forms a hole in the target cell, electrolytes leak out, water flows in rapidly and the cell ruptures
Cytokines
Mediate cell development, differentiation, and responses in the immune system plus include interleukins and interferons.
Thymus
Member of the endocrine, lymphatic, and immune systems; Houses developing T cells; Goes through involution; Location where T cells become immunocompetent
IgE
Monomer active in some allergies and parasitic infections and causes mast cells and basophils to release histamine.
IgD
Monomer attached to the surface of B cells and functions as a B cell receptor, and pump plus antigen receptor found on B cells.
IgA
Monomer in plasma; Provides passive immunity to newborns
IgA
Monomer or dimer; in mucus and other secretions, helps prevent entry of pathogens, and in all body fluids.
IgG
Monomer that constitutes 80% of circulating antibodies
IgE
Monomer that stimulates the release of histamine and other chemical mediators of inflammation
IgD
Monomer which functions in B cell activation
IgG
Monomer; 75-85% of antibodies in plasma, from secondary and late primary responses, crosses the placental barrier, abundant, and cross placenta barrier plus most abundant class of antibodies.
Fate of Clone Cells
Most clone cells become plasma cells that secrete specific antibodies at the rate of 2,000 molecules per second for four to five days. Secreted antibodies by: circulate in blood or lymph, bind to free antigens, and mark the antigens for destruction.
Lymph Nodes
Most numerous lymphatic organs; Cleanses the lymph and act as a site of T and B cells activation
Alpha (α) Interferon
Most other WBC's produce this.
Edema
Moves foreign material into lymphatic vessels and delivers clotting proteins to form a scaffold for repair and to isolate the area.
Respiratory System Modifications
Mucus-coated hairs in the nose and cilia of upper respiratory tract sweep dust- and bacteria-laden mucus from lower respiratory passages.
Secondary Immune Response
Occurs on re-exposure to the same antigen, sensitized memory cells respond within hours, antibody levels peak in two to three days at much higher levels, antibodies bind with greater affinity, antibody level can remain high for weeks to months plus last longer than a primary immune response.
Primary Immune Response
Occurs on the first exposure to a specific antigen, lag period: three to six days, peak levels of plasma antibody are reached in 10 days, antibody levels then decline.
T or Y Shaped Monomer
Of 4 looping linked polypeptide chains, two identical heavy chains and two identical light chains and variable regions of each arm combine to form two identical antigen-binding sites.
Constant Region
Of stem determines: the antibody class, cells and chemical that the antibody can bind to, and how the antibody class functions in antigen elimination.
Lingual Tonsils
Pair of tonsils at the root of the tongue
Surface Barriers
Part of internal defense by the Skin, mucous membranes, and their secretions by physical barrier to most microorganisms, keratin is resistant to weak acids and bases, bacterial enzymes, and toxins and mucosae provide similar mechanical barriers plus Protective chemicals inhibit or destroy microorganisms • Skin acidity • Lipids in sebum and dermcidin in sweat • HCl and protein-digesting enzymes of stomach mucosae • Lysozyme of saliva and lacrimal fluid • Mucus
Tonsils
Patches of lymphatic tissue located at the entrance to the pharynx
Basophils
Phagocytes that secrete histamine and heparin
Eosinophils
Phagocytes that stand guard against parasites and allergens; Limit action of histamine and other inflammatory chemicals; Found in mucous membranes
Phagocytes
Phagocytic cells with voracious appetite for foreign matter
Memory
Phase of immunity in which some cytotoxic and helper T cells develop a recall so as to issue a quick attack upon re-exposure to the same pathogen later in life
Attack
Phase of immunity in which the helper T cells secrete interleukins that attract neutrophils, NK cells, and macrophages; Cytotoxic cells deliver a lethal hit of toxic chemicals
Recognition
Phase of immunity that includes antigen presentation and T cell activation
Immune System
Population of cells that inhabit all of our organs and defend the body from agents of disease; not an organ system
Immune Surveillance
Process in which natural killer cells release perforins that form a hole in the target cells plasma membrane and secrete granzymes that induce apoptosis
Natural Active Immunity
Production of one's own antibodies or T cells as a result of infection or natural exposure to an antigen
Artificial Active Immunity
Production of one's own antibodies or T cells as a result of vaccination against disease
Adaptive Immune System
Protects against infectious agents and abnormal body cells, amplifies the inflammatory response, activates complement, and specific defense.
Self-Antigens: MHC Proteins
Protein molecules (self-antigens) on the surface of cells, antigenic to others in transfusions or grafts (example: MHC proteins) coded for by genes of the major histocompatibility complex (MHC) and are unique to an individual.
Perforins
Proteins that polymerize a ring and create a hole in the plasma membrane of a target cell
T Cells of the Cell-Mediated Response
Recognize and respond only to processed fragments of antigen displayed on the surface of body cells Targets • Body cells infected by viruses or bacteria • Abnormal or cancerous cells • Cells of infused or transplanted foreign tissue
Natural Killer Cells
Recognize other signs of abnormality: • Lack of class I MHC • Antibody coating a target cell • Different surface marker on stressed cells • Use the same key mechanisms as Tc cells for killing their target cells
Activated T Cells
Release chemicals that: Prod macrophages to become insatiable phagocytes and to secrete bactericidal chemicals.
T Cell Activation: Co-Stimulation
Requires T cell binding to other surface receptors on an APC, dendritic cells and macrophages produce surface B7 proteins when innate defenses are mobilized, and B7 binding with a CD28 receptor on a T cell is a crucial co-stimulatory signal.
Lymphatic System
Resistance to disease and has two intrinsic systems: • Innate (nonspecific) defense system • Adaptive (specific) defense system
Primary T Cells
Response peaks within a week, T cell apoptosis occurs between days 7 and 30, effector activity wanes as the amount of antigen declines, benefit of apoptosis: activated T cells are a hazard, memory T cells remain and mediate secondary responses.
Active Naturally Acquired
Response to a bacterial or viral infection.
Active Artificially Acquired
Response to a vaccine of dead or attenuated pathogens.
Memory Cells
Responsible for memory in cellular immunity for future exposure to an antigen
Lymphatic Capillaries - Collecting Vessels - 6 Lymphatic Trunks - 2 Collecting Ducts - Subclavian Veins
Route of Lymph Flow
Classical Pathway
Route of the complement activation that requires an antibody molecule to get started; Part of specific immunity
Alternative Pathway, Lectin Pathway
Routes of the complement activation that are nonspecific and do not require an antibody
Cisterna Chyli
Sac in the abdomen that receives lymph; Begins thoracic duct
Interferons
Secreted by certain cells infected by viruses; Alert neighboring cells (NK cells and macrophages) and protect them from becoming infected
Clonal Deletion
Self-reactive T cells die and macrophages phagocytize them (Negative Selection)
Anergy
Self-reactive T cells remain alive but unresponsive (Negative Selection)
Neutralization
Simplest mechanism, antibodies block specific sites on viruses or bacterial exotoxins, prevent these antigens from binding to receptors on tissue cells, and antigen-antibody complexes undergo phagocytosis.
Pharyngeal (Adenoid) Tonsil
Single tonsil on the wall of the nasopharynx; Intercepts inhaled pathogens
Red Pulp
Sinuses of the spleen filled with erythrocytes
Primary Lymphatic Organs
Sites where T and B cells become immunocompetent
Peyer's Patches
Small intestine (end part of ilium).
Haptens (Incomplete Antigens)
Small molecules (peptides, nucleotides, and hormones), not immunogenic by themselves, are immunogenic when attached to body proteins, cause the immune system to mount a harmful attack. Ex: Poison ivy, animal dander, detergents, and cosmetics.
Precipitation
Soluble molecules are cross-linked and complexes precipitate and are subject to phagocytosis.
Vaccines
Spare us the symptoms of the primary response, provide antigenic determinants that are immunogenic and reactive, target only one type of helper T cell, so fail to fully establish cellular immunological memory.
Immunity
Specific defense because it results from prior exposure to a pathogen; usually provides future protection only against that particular one (vaccine)
Antigens
Substances that can mobilize the adaptive defenses and provoke an immune response and most are large, complex molecules not normally found in the body (nonself).
Both Types of MHC Proteins
Synthesized at the ER and bind to peptide fragments.
Third Line of Defense
The immune system; results from prior exposure, defeats specific pathogen, and leaves the body a 'memory' of it so it can defeat it faster in the future (vaccine)
Fever
Systemic response to invading microorganisms, leukocytes and macrophages exposed to foreign substances secrete pyrogens, reset the body's thermostat upward, high fevers are dangerous because heat denatures enzymes, benefits of moderate fever, causes the liver and spleen to sequester iron and zinc (needed by microorganisms) plus increases metabolic rate, which speeds up repair and not a sign of inflammation.
Cell-Mediated Immune Response
T cells provide defense against intracellular antigens, two types of surface receptors of T cells, T cell antigen receptors: • Cell differentiation glycoproteins • CD4 or CD8 • Play a role in T cell interactions with other cells
) If even a small part of the spleen is left in a ten-year-old child, it will most likely regenerate itself
TRUE
) Lymphocytes reside temporarily in lymphoid tissue, then move to other parts of the body.
TRUE
2) The lymphatics function to absorb the excess protein-containing interstitial fluid and return it to the bloodstream
TRUE
About 3 liters of fluid are lost to the tissue spaces every 24 hours and are returned to the bloodstream as lymph
TRUE
An infected lymph gland is called a bubo
TRUE
Because lymph vessels are very low-pressure conduits, movements of adjacent tissues are important in propelling lymph through the lymphatics
TRUE
Chyle is delivered to the blood via the lymphatic system
TRUE
Digested fats are absorbed from the intestine by the lymph capillaries.
TRUE
Lymphatic capillaries are permeable to proteins
TRUE
Lymphoid tissue is mainly reticular connective tissue
TRUE
Natural Passive Immunity
Temporary immunity that results from antibodies produced by another person; Fetus acquires antibodies from mother through placenta
Artificial Passive Immunity
Temporary immunity that results from the injection of immune serum from another person or animal; Antivenum for a snake bite
Lymphocyte is a B Cell
The antigen provokes a humoral immune response and antibodies are produced.
Spleen
The body's largest lymphatic organ; Functions in blood production in the fetus, as a blood reservoir, in RBC disposal, and monitors blood for foreign antigens; Highly vascular and vulnerable to trauma and infection
Inflammatory Chemicals
This cause: • Dilation of arterioles, resulting in hyperemia • Increased permeability of local capillaries and edema (leakage of exudate) Exudate contains proteins, clotting factors, and antibodies.
Inflammatory Response
Triggered whenever body tissues are injured or infected, prevents the spread of damaging agents, disposes of cell debris and pathogens, sets the stage for repair, Cardinal signs of acute inflammation: 1. Redness 2. Heat 3. Swelling 4. Pain (And sometimes 5. Impairment of function)
Bone Marrow
Where self-reactive B cells are eliminated at.
8) The lymphatic capillaries are ________. A) more permeable than blood capillaries B) less permeable than blood capillaries C) equally permeable to blood capillaries D) completely impermeable
a
1) Small organs associated with lymphatic vessels are termed ________. A) lymph follicles B) lymph nodes C) axillary nodes D) cisterna chyli
b
3) The distal portion of the small intestine contains clumps of lymph follicles called ________. A) islets of Langerhans B) Peyer's patches C) rugae D) villi
b
4) Both lymph and venous blood flow are heavily dependent on ________. A) the pumping action of the heart B) skeletal muscle contractions and differences in thoracic pressures due to respiratory movement C) contraction of the vessels themselves D) two-way valves
b
5) The thymus is most active during ________. A) fetal development B) childhood C) middle age D) old age
b
6) Which lymphatic structure drains lymph from the right upper limb and the right side of the head and thorax? A) lumbar trunk B) thoracic duct C) right lymphatic duct D) cisterna chyli
c
Complement
~20 blood proteins that circulate in an inactive form, include C1-C9, factors B, D, and P, and regulatory proteins, major mechanism for destroying foreign substances, amplifies all aspects of the inflammatory response, kills bacteria and certain other cell types by cell lysis, and enhances both nonspecific and specific defenses.
Hodgkin's Disease
• An acquired immunodeficiency • Cancer of the B cells • Leads to immunodeficiency by depressing lymph node cells
Immune Complex (Type III) Hypersensitivity
• Antigens are widely distributed through the body or blood • Insoluble antigen-antibody complexes form • Complexes cannot be cleared from a particular area of the body • Intense inflammation, local cell lysis, and death may result • Example: systemic lupus erythematosus (SLE)
Acquired Immune Deficiency Syndrome (AIDS)
• Cripples the immune system by interfering with the 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
Prevention of Rejection
• Depends on the similarity of the tissues • Patient is treated with immunosuppressive therapy • Corticosteroid drugs to suppress inflammation • Antiproliferative drugs • Immunosuppressant drugs • Many of these have severe side effects
Roles of Cytotoxic T(TC) Cells
• Directly attack and kill other cells • Activated TC cells circulate in blood and lymph and lymphoid organs in search of body cells displaying antigen they recognize Targets: • Virus-infected cells • Cells with intracellular bacteria or parasites • Cancer cells • Foreign cells (transfusions or transplants) Carry out cellular immune responses
Severe Combined Immunodeficiency (SCID) Syndrome
• Genetic defect • Marked deficit in B and T cells • Abnormalities in interleukin receptors • Defective adenosine deaminase (ADA) enzyme • Metabolites lethal to T cells accumulate • This is fatal if untreated; treatment is with bone marrow transplants
Making of AIDS
• HIV multiplies in lymph nodes throughout the asymptomatic period • Symptoms appear in a few months to 10 years • HIV-coated glycoprotein complex attaches to the CD4 receptor • HIV enters the cell and uses reverse transcriptase to produce DNA from viral RNA • The DNA copy (a provirus) directs the host cell to make viral RNA and proteins, enabling the virus to reproduce • HIV reverse transcriptase produces frequent transcription errors; high mutation rate and resistance to drugs • Treatment with antiviral drugs • Reverse transcriptase inhibitors (AZT) • Protease inhibitors (saquinavir and ritonavir) • New Fusion inhibitors that block HIV's entry to helper T cells
Inflammatory Mediators
• Histamine (from mast cells) • Blood proteins • Kinins, prostaglandins (PGs), leukotrienes, and complement Released by injured tissue, phagocytes, lymphocytes, basophils, and mast cells.
Acute (Type I) Reactions
• Hypersensitivities (allergies) begin in seconds after contact with allergen • Initial contact is asymptomatic but sensitizes the person • Reaction may be local or systemic • The mechanism involves IL-4 secreted by T cells • IL-4 stimulates B cells to produce IgE • IgE binds to mast cells and basophils, resulting in a flood of histamine release and inducing the inflammatory response • Systemic response to allergen that directly enters the blood • Basophils and mast cells are enlisted throughout the body • Systemic histamine releases may cause • Constrict ion of bronchioles • Sudden vasodilation and fluid loss from the bloodstream • Hypotensive shock and death • Treatment: epinephrine
Hypersensitivities
• Immune responses to a perceived (otherwise harmless) threat • Causes tissue damage • Different types are distinguished by • Their time course • Whether antibodies or T cells are involved • Antibodies cause immediate and subacute hypersensitivities • T cells cause delayed hypersensitivity
Autoimmune Diseases
• Immune system loses the ability to distinguish self from foreign • Production of autoantibodies and sensitized TC cells that destroy body tissues • Examples include multiple sclerosis, myasthenia gravis, Graves' disease, type I diabetes mellitus, systemic lupus erythematosus (SLE), glomerulonephritis, and rheumatoid arthritis
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 • B cells may be activated without TH cells by binding to T cell-independent antigens • Most antigens require TH co-stimulation to activate B cells • Cause dendritic cells to express co- stimulatory molecules required for CD8 cell activation
Roles of Helper T(TH) Cells
• Play a central role in the adaptive immune response, once primed by APC presentation of antigen, they: • Help activate T and B cells • Induce T and B cell proliferation •Activate macrophages and recruit other immune cells • Without TH, there is no immune response
Delayed Hypersensitivities
• Slow onset (one to three days) • Mechanism depends on helper T cells • Cytokine-activated macrophages and cytotoxic T cells cause damage • Example: allergic contact dermatitis (e.g., poison ivy)
Cytoxic (Type II) Reactions
•Antibodies bind to antigens on specific body cells, stimulating phagocytosis and complement-mediated lysis of the cellular antigens •Example:mismatched blood transfusion reaction
