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Anatomy and Physiology - Wiley Plus - Unit 3
Chapter 22 - THE LYMPHATIC SYSTEM AND IMMUNITY
106
Biology
Undergraduate 2
06/26/2015

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Term
Pathogens
Definition
Disease-producing microbes such as bacteria and viruses
Term
Resistance
Definition
The ability to ward off damage or disease through our defenses
Term
Susceptibility
Definition
Vulnerability or lack of resistance
Term
Innate (nonspecific) Immunity
Definition
- Defenses that are present at birth. -- Does not involve specific recognition of a microbe and acts against all microbes in the same way
Term
Adaptive (specific) immunity
Definition
Defenses that involve specific recognition of a microbe once it has breached the innate immunity defenses
Term
Lymphatic System
Definition
- Consists of a fluid called lymph, vessels called lymphatic vessels that transport the lymph, a number of structures and organs containing lymphatic tissue (lymphocytes within a filtering tissue), and red bone marrow
Term
Lymph
Definition
After interstitial fluid passes into lymphatic vessels, it is called lymph
Term
Lymphatic tissue
Definition
- A specialized form of reticular connective tissue
- Contains large numbers of lymphocytes
Term
Functions of the Lymphatic System
Definition
1. Drains excess interstitial fluid
2. Transports dietary lipids
3. Carries out immune responses
Term
Lymphatic Capillaries
Definition
- Located in the spaces b/t cells
- Greater permeability than blood capillaries
- Can absorb large molecules such as proteins and lipids
- When pressure is greater in the interstitial fluid than in lymph, the cells separate slightly, like the open- ing of a oneway swinging door, and interstitial fluid enters the lymphatic capillary.
Term
Lymphatic Vessels
Definition
- Lymphatic capillaries unite to form
- Resemble small veins in structure but have thinner walls and more valves
Term
Lacteals
Definition
- In small intestine
- Carry dietary lipids into lymphatic vessels and ultimately into the blood
Term
Chyle
Definition
Lymph in small intestine
Term
Lymph Trunks
Definition
As lymphatic vessels exit lymph nodes in a particular region of the body, they unite to form lymph trunks
Term
Cisterna Chyli
Definition
Receives lymph from the right and left lumbar trunks and from the intes- tinal trunk
Term
Right Lymphatic Duct
Definition
- Receives lymph from right jugular, right subclavian, and right bronchomediastinal trunks
- Lymph from the upper right side of the body
Term
Formation and Flow of Lymph
Definition
Sequence of fluid flow is blood capillaries (blood) -> interstitial spaces (interstitial fluid) -> lymphatic capillaries (lymph) -> lymphatic vessels (lymph) -> lymphatic ducts (lymph) -> junction of the internal jugular and subclavian veins (blood)
Term
Skeletal muscle pump.
Definition
- The “milking action” of skeletal muscle contractions compresses lymphatic vessels (as well as veins) and forces lymph toward the junction of the internal jugular and subclavian veins
Term
Respiratory pump
Definition
Lymph flow is also maintained by pres- sure changes that occur during inhalation (breathing in)
Term
Primary Lymphatic Organs
Definition
Sites where stem cells divide and become immunocompetent
- Red bone marrow
- Thymus
Term
Immunocompetent
Definition
- Derived from stems cells
- Capable of mounting an immune response
Term
Secondary Lymphatic Organs and Tissues
Definition
- Sites where most immune responses occur
- Lymph nodes, the spleen, and lymphatic nodules (follicles)
- Thymus, lymph nodes, and spleen
Term
Thymus Capsule
Definition
Connects two lobes
Term
Trabeculae
Definition
Extensions of the capsule
Term
Cortex
Definition
Composed of large numbers of T cells and scattered dendritic cells, epithelial cells, and macrophages
Term
Dendritic Cells
Definition
- Derived from monocytes
- Present antigens to T cells, causing their proliferation. T
Term
Macrophages
Definition
Help clear out the debris of dead and dying cells.
Term
Medulla
Definition
- Consists of widely scattered, more mature T cells, epithelial cells, dendritic cells, and macrophages
- Contains B cells, antibody-producing plasma cells that have migrated out of the cortex into the medulla, and macrophages.
- The various cells are embedded in a network of reticular fibers and reticular cells
Term
Lymph Nodes
Definition
- Scattered throughout body, both su- perficially and deep,
- Usually occur in groups
Term
Capsule
Definition
- Cover lymph nodes
- Dense connective tissue
Term
Trabeculae
Definition
- Capsular extensions
- Divide node into compartments, provide support, and provide a route for blood vessels into the interior of a node
Term
Lymphatic Nodules (follicles)
Definition
- Egg-shaped aggregates of B cells called
- Sites of plasma cell and memory B cell formation.
Term
Inner Cortex
Definition
- Does not contain lymphatic nodules
- Consists mainly of T cells and dendritic cells that enter a lymph node from other tissues
Term
Afferent Lymphatic Vessels
Definition
- Afferent vessels contain valves that open toward the center of the node, directing the lymph inward
Term
Sinuses
Definition
- Within the node, lymph enters sinuses
- A series of irregular channels that contain branching reticular fibers, lymphocytes, and macrophages
Term
Efferent Lymphatic Vessels
Definition
- Medullary sinuses drain into
- Contain valves that open away from center of the lymph node to convey lymph, antibodies secreted by plasma cells, and activated T cells out of the node.
Term
Hilum
Definition
- A slight depression from which an efferent lymphatic vessels emerge from one side of the lymph node
Term
White Pulp
Definition
- Lymphatic tissue, consisting mostly of lymphocytes and macrophages arranged around branches of the splenic artery
- B cells and T cells carry out immune functions, similar to lymph nodes, while spleen macrophages destroy blood-borne pathogens by phagocytosis
Term
Red Pulp
Definition
The spleen performs three functions related to blood cells:
(1) removal by macrophages of ruptured, worn out, or defective blood cells and platelets;
(2) storage of platelets, up to one-third of the body’s supply; and
(3) production of blood cells (hemopoiesis) during fetal life
Term
Mucosa-associated Lymphatic Tissue (MALT)
Definition
Lymphatic nodules (follicles
Term
Tonsils
Definition
Strategically positioned to participate in immune responses against inhaled or ingested foreign substances
Term
Pharyngeal Tonsil & Adenoid
Definition
Embedded in the posterior wall of the nasopharynx.
Term
Palatine Tonsils (x2)
Definition
- Lie at posterior region of oral cavity, one on either side;
- Tonsils commonly removed in a tonsillectomy
Term
Lingual Tonsils
Definition
Located at the base of the tongue, may also require removal during a tonsillectomy
Term
First Line of Defense: Skin and Mucous Membranes
Definition
- Provide both physical and chemical barriers that discourage pathogens and foreign substances from penetrating the body and causing disease
- Provides a formidable physical barrier to the entrance of microbes
- Epidermis
- Mucous Membranes
- Mucus
Term
Second Line of Defense: Internal Defense
Definition
- Internal antimicrobial substances
- Phagocytesa
- Natural killer cells
- Inflammation
- Fever
Term
Antimicrobial Substances
Definition
Discourage microbial growth: interferons, complement, iron-binding proteins, and antimicrobial proteins.
Term
Interferons
Definition
Proteins produced be lymphocytes, macrophages, and fibroblasts infected with viruses
Term
Complement System
Definition
- Proteins “complement” or enhance certain immune reactions
- The complement system causes cytolysis (bursting) of microbes, promotes phagocytosis, and contributes to inflammation.
Term
Iron-binding Protein
Definition
Inhibit growth of certain bacteria by reducing the amount of available iron ex. transferrin
Term
Antimicrobial Proteins (AMPs)
Definition
Attract dendritic cells and mast cells, which participate in immune responses.
Term
Natural Killer (NK) Cells
Definition
- Present in the spleen, lymph nodes, and red bone marrow
- Lack membrane molecules that identify B and T cells
- Have ability to kill wide variety of infected body cells and certain tumor cells
Term
Perforin
Definition
- Inserts into plasma membrane of the target cell and creates channels (perforations) in the membrane.
- Extracellular fluid flows into target cell and the cell bursts, a process called cytolysis
Term
Five Phases of Phagocytosis
Definition
1. Chemotaxis
2. Sdherence
3. Ingestion
4. Digestion
5. Killing
Term
Chemotaxis
Definition
- Chemically stimulated movement of phagocytes to a site of damage
- Chemicals that attract phagocytes might come from invading microbes, white blood cells, damaged tissue cells, or activated complement proteins.
Term
Adherence
Definition
- Attachment of the phagocyte to the microbe or other foreign material
- Binding of complement proteins to the invading pathogen enhances adherence
Term
Ingestion
Definition
- Plasma membrane of the phagocyte extends projections that engulf the microbe
Term
Digestion
Definition
- Phagosome enters the cytoplasm and merges with lysosomes
- lysosome contributes lysozyme, which breaks down microbial cell walls, and other digestive enzymes that degrade carbohydrates, proteins, lipids, and nucleic acids.
Term
Killing
Definition
- Chemical onslaught provided by lysozyme, digestive enzymes, and oxidants within a phagolysosome quickly kills many types of microbes
Term
Inflammation
Definition
Nonspecific, defensive response of the body to tissue damage
Term
Causes of Inflammation
Definition
Pathogens, abrasions, chemical irritations, distortion or disturbances of cells, and extreme temperatures.
Term
Histamine
Definition
- Mast cells in connective tis sue and basophils and platelets in blood release histamine.
- Neutrophils and macrophages attracted to the site of injury also stimulate the release of histamine, which causes vasodilation and increased permeability of blood vessels.
Term
Kinins
Definition
- Induce vasodilation and increased permeability and serve as chemotactic agents for phagocytes
Term
Prostaglandins
Definition
- Lipids, released by damaged cells and intensify the effects of histamine and kinins.
- PGs also may stimulate the emigration of phagocytes through capillary walls.
Term
Leukotrienes
Definition
- Produced by basophils and mast cells
- Cause increased permeability; they also function in adherence of phagocytes to pathogens and as chemotactic agents that attract phagocytes
Term
Complement
Definition
Attract neutrophils by chemotaxis, and promote phagocytosis; some components can also destroy bacteria
Term
Emigration
Definition
Neutrophils begin to squeeze through the wall of the blood vessel to reach the damaged area
Term
Leukocytosis
Definition
An increase in white blood cells in the blood
Term
Pus
Definition
Collection of dead cells and fluid
Term
Adaptive (specific) Immunity.
Definition
- Ability of body to defend itself against specific invading agents such as bacteria, toxins, viruses, and foreign tissues
Term
Two properties distinguish adaptive immunity from innate immunity
Definition
Specificity & Memory
Term
Antigens
Definition
Substances that are recognized as foreign and provoke immune responses
Term
B cells
Definition
Complete their development in red bone marrow, a process that continues throughout life
Term
T cells
Definition
Cells develop from pre-T cells that migrate from red bone marrow into the thymus, where they mature
Term
Immunocompetence
Definition
- The ability to carry out adaptive immune responses
- Takes place before T cells leave the thymus or B cells leave red bone marrow
Term
Antigen Receptors
Definition
Molecules capable of recognizing specific antigens
Term
Two Major Types of Mature T Cells
Definition
- Exit thymus
- Helper T cells and cytotoxic T cells
Term
Helper T cells (aka. CD4 T Cells)
Definition
Term
Cytotoxic T Cells (aka CD8 T Cells)
Definition
Term
Cell-mediated Immunity
Definition
Cytotoxic T cells directly attack invading antigens
Term
Antibody-mediated Immunity
Definition
B cells transform into plasma cells, which synthesize and secrete specific proteins called antibodies (Abs) or immunoglobulins (Igs)
Term
Cell-mediated Immunity
Definition
Particularly effective against
(1) Intracellular pathogens, which include any viruses, bacteria, or fungi that are inside cells;
(2) some cancer cells
(3) foreign tissue transplants
Term
Antibody-mediated Immunity
Definition
Works mainly against extracellular pathogens, which include any viruses, bacteria, or fungi that are in body fluids outside cells
Term
B-cell receptors (BCRs)
Definition
- Integral transmembrane proteins
- Chemically similar to the antibodies that eventually are secreted by plasma cells
Term
Plasma Cells
Definition
- Secrete antibodies
- A few days after exposure to an antigen, plasma cell secretes hundreds of millions of antibodies each day for about 4 or 5 days, until the plasma cell dies.
Term
Memory B cells
Definition
- Do not secrete antibodies
- Quickly proliferate and differentiate into more plasma cells and more memory B cells should the same antigen reappear at a future time.
Term
Antibodies
Definition
- Combine specifically with the epitope on the antigen that triggered its production
- Structure matches its antigen much as a lock accepts a specific key
Term
Antibody Structure
Definition
Belong to a group of glycoproteins called globulins
Term
Immunoglobulins
Definition
- IgG
- Appear first
- Relatively short-lived
- Indicate a recent invasion
Term
T shape or a Y shape
Definition
Because the antibody “arms” can move somewhat as the hinge region bends, an antibody can assume either a T shape or a Y shape
Term
Antigen-binding Site
Definition
- Most antibodies have two antigen-binding sites
- Variable region, which is different for each kind of antibody, is the part of the antibody that recognizes and attaches specifically to a particular antigen.
Term
Antibody Actions
Definition
1. Neutralizing antigen
2. Immobilizing bacteria
3. Agglutinating and precipitating antigen.
4. Activating complement
5. Enhancing phagocytosis
Term
Neutralizing Antigen
Definition
Reaction of antibody with antigen blocks or neutralizes some bacterial toxins and prevents attachment of some viruses to body cells.
Term
Immobilizing Bacteria
Definition
If antibodies form against antigens on the cilia or flagella of motile bacteria, the antigen–antibody reaction may cause the bacteria to lose their motility, which limits their spread into nearby tissues
Term
Agglutinating and Precipitating Antigen
Definition
- Antibodies have two or more sites for binding to antigen
- Antigen– antibody reaction may cross-link pathogens to one another, causing agglutination (clumping together). Phagocytic cells ingest agglutinated microbes more readily.
- Likewise, soluble antigens may come out of solution and form a more easily phagocytized precipitate when cross-linked by antibodies.
Term
Activating Complement
Definition
Antigen–antibody complexes initiate the classical pathway of the complement system
Term
Enhancing Phagocytosis
Definition
- Stem region of antibody acts as flag, attracts phagocytes once antigens have bound to the antibody’s variable region
- Enhance activity of phagocytes by causing agglutination and precipitation, by activating complement, and by coating microbes so that they are more susceptible to phagocytosis
Term
Complement System
Definition
- Defensive system made up of over 30 proteins produced by the liver and found circulating in blood plasma and within tissues throughout the body
Term
Role of the Complement System in Immunity
Definition
- Complement proteins destroy microbes by causing phagocytosis, cytolysis, and inflammation; they also prevent excessive damage to body tissues
Term
Immunological Memory
Definition
- Due to presence of long-lasting antibodies and very long-lived lymphocytes that arise during clonal selection of antigen-stimulated B cells and T cells.
Term
Primary Response
Definition
- After initial contact with antigen, no antibodies are present for a period of several days
- slow rise in antibody titer occurs, first IgM and then IgG, followed by gradual decline in antibody titer
Term
Secondary Response
Definition
After subsequent encounters, antibody titer is far greater than during a primary response and consists mainly of IgG antibodies.
Term
Self-recognition
Definition
T-cells must be able to recognize your own major histocompatibility com- plex (MHC) proteins,
Term
Self-tolerance
Definition
T-cells must lack reactivity to peptide fragments from your own proteins, a condition
Term
Infectious Mononucleosis
Definition
- A contagious disease caused by the Epstein–Barr virus (EBV).
- Fatigue, headache, dizziness, sore throat, enlarged and tender lymph nodes, and fever.
Term
Systemic Lupus Erythematosus
Definition
- A chronic autoimmune, inflammatory disease that affects multiple body systems
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