Chr. 22 - The Lymphatic System and Immunity Flashcards
[22.1] What is immunity?
The ability to ward off damage or disease through defenses.
[22.1] What is susceptibility?
Vulnerability or lack of resistance.
[22.1] What are the types of immunity?
Innate and adaptive.
[22.1] What is innate immunity?
External physical and chemical barriers of skin and mucous membranes. Defenses present at birth, not involving recognition of microbes. Indiscriminate in its reaction.
[22.1] What is adaptive immunity?
The defenses involving specific recognition of microbes once innate immunity has been breached.
[22.1] List the cells involved in adaptive immunity.
- T lymphocytes
- B lymphocytes
[22.2] List the components of the lymphatic system.
- Lymph
- Lymphatic vessels
- Lymphatic organs
- Red bone marrow
[22.2] What is lymph?
Interstitial fluid that has passed into lymphatic vessels.
[22.2] What is lymphatic tissue?
Specialized form of reticular connective tissue containing large numbers of lymphocytes.
[22.2] List and describe the functions of the lymphatic system.
- Drain excess interstitial fluid
- Transport dietary lipids
- Carry out immune response
[22.3] What are lymphatic capillaries?
Capillaries located between cells and closed at one end, disallowing for backflow into interstitial fluid. Greater permeability than blood capillaries, allow in proteins and lipids.
[22.3] What are lymphatic vessels?
Vessels resembling veins with greater amounts of valves and thinner walls.
[22.3] What are lacteals?
Specialized lymphatic capillaries carrying dietary lipids into lymphatic vessels/
[22.3] What is chyle?
Lymph from the small intestine, white in appearance due to the lipids within.
[22.3] What is a lymph trunk?
Larger lymph vessels formed by uniting of smaller vessels.
[22.3] List the principal lymphatic trunks.
- Lumbar
- Intestinal
- Bronchomediastinal
- Subclavian
- Jugular.
[22.3] What regions do the lumbar trunks drain?
Lymph from the lower limbs, wall and viscera of pelvis, kidneys, adrenal glands, abdominal wall
[22.3] What regions do the intestinal trunks drain?
Stomach, intestines, pancreas, spleen, and part of liver.
[22.3] What regions do the bronchomediastinal trunks drain?
Thoracic wall, lungs, and heart.
[22.3] What regions do the subclavian trunks drain?
Upper limbs
[22.3] What regions do the jugular trunks drain?
The head and the neck.
[22.3] What are the pumps that maintain flow of lymph?
Respiratory pump and skeletal muscle pump.
[22.4] What are primary lymphatic organs?
Sites where stem cells divide and become immunocompetent.
[22.4] List the primary lymphatic organs.
- Red bone marrow
- Thymus.
[22.4] What are secondary lymphatic organs?
The sites where immune responses occur.
[22.4] List the secondary lymphatic organs and tissues.
- Lymph nodes
- Spleen
- Lymphatic nodules.
[22.4] Describe the thymus.
Bilobed organ in the mediastinum between sternum and aorta. Contains a connective tissue capsule enclosing each lobe that features extensions separating the lobes into lobules. Consists of an outer cortex and medulla.
[22.4] Describe the composition of the cortex of the thymus.
Tissue of the thymus composed of immature T cells, scattered dendritic cells, epithelium, and macrophages.
[22.4] Describe the composition of the medulla of the thymus.
Tissue composed of mature T cells, epithelium, dendritic cells, and macrophages. Epithelium features thymic corpuscles.
[22.4] What are thymic corpuscles?
Concentric epithelial layers of flat cells filled with keratohyalin granules and keratin.
[22.4] Describe lymph nodes.
Small, long bean-shaped bodies covered by a capsule of connective tissue similarly sectioned like the thymus. Features supporting reticular fibers and fibroblasts deep of the capsule. Separated into the stroma and parenchyma.
[22.4] What is the stroma of a lymph node?
The supporting network region of the lymph node containing the capsule, trabeculae, reticular fibers, and fibroblasts.
[22.4] What is the parenchyma of a lymph node?
The functioning region of a lymph node divided into a cortex and medulla.
[22.4] What are lymphatic nodules?
Egg-shaped aggregates of B cells within the cortex of a lymph node
[22.4] What are primary and secondary lymphatic nodules?
Primary lymphatic nodules consist mainly of B cells and function to recognize antigens.
Secondary lymphatic nodules function to respond to antigens and form plasma cells and memory B cells.
[22.4] Describe the cortex of lymph nodes.
Divided into inner and outer cortex. Outer cortex features lymphatic nodules, inner cortex composed of dendritic cells and T cells.
[22.4] Describe the medulla of lymph nodes.
Composed of B cells and antibody-producing plasma cells embedded in a network of reticular fibers and reticular cells.
[22.4] What are afferent lymphatic vessels?
Vessels carrying lymph towards the lymph nodes
[22.4] What are lymph sinuses?
Series of irregular channels within a lymph node.
[22.4] List the sinuses of a lymph node.
- Subscapular sinus
- Trabecular sinus
- Medullary sinus.
[22.4] What are efferent lymphatic vessels?
Wider vessels carrying lymph away from lymph nodes.
[22.4] What is the hilum of lymph nodes?
A depression of the lymph node at the junction where efferent lymph vessels emerge from lymph nodes.
[22.4] Describe the spleen.
A soft, encapsulated organ in the left hypochondriac region between stomach and diaphragm. Covered by a visceral peritoneum, serous membrane, then capsule. The parenchyma consists of red and white pulp.
[22.4] What is white pulp?
Lymphatic tissue consisting mostly of lymphocytes and macrophages centered around the splenic artery.
[22.4] What is red pulp?
Blood-filled venous sinuses of the spleen featuring splenic cords.
[22.4] What is a splenic cord?
Cord consisting of red blood cells, macrophages, lymphocytes, plasma cells, and granulocytes.
[22.4] List the functions of red pulp related to blood cells.
- Removal of ruptured/old blood cells and platelets
- Storage of platelets
- Production of blood cells during fetal life
[22.4] Describe lymphatic nodules.
Egg-shaped masses of lymphatic tissue lacking a capsule. Scattered throughout lamina propria of mucous membranes in GI, urinary, and reproductive tracts, as well as the respiratory tissue.
[22.4] What is mucosa-associated lymphatic tissue?
Lymphatic nodules within the GI, urinary, and reproductive tracts, as well as in respiratory tissue.
[22.4] List the tonsils of the oral cavity and oropharynx.
- Singular pharyngeal tonsils
- Paired palatine tonsils
- Paired lingual tonsils
[22.6] List the lines of defense of innate immunity
- First line, skin and mucous membranes
- Second line, internal defenses
[22.6] What is the first line of defense?
The physical and chemical barriers discouraging pathogens from penetrating the body, formed by the skin and mucous membranes.
[22.6] Describe how the epidermis acts as a line of defense.
Featuring closely packed keratinized cells, the epidermis forms a physical barrier preventing entrance of microbes.
[22.6] Describe how mucous membranes act as a line of defense.
Secretion of mucus lubricates and moistens cavity surfaces, trapping microbes and foreign substances, typically found in conjunction with hair and cilia.
[22.6] List other fluids produced by organs that aid in protecting epithelial surfaces.
- Lacrimal fluid containing lysozyme
- Saliva
- Urine aids in cleaning the urethra and retarding microbial growth
- Vaginal secretions
[22.6] List chemicals contributing the resistance of skin and mucous to microbial invasion.
- Sebum
- Perspiration
- Gastric juice
[22.6] What are second line, internal defenses?
Internal antimicrobial substances, immune cells, and body reactions such as inflammation and fever.
[22.6] What are antimicrobial substances?
Substances discouraging microbial growth.
[22.6] List the types of antimicrobial substances found within the body.
- Interferons
- Complement
- Iron-binding proteins
- Antimicrobial proteins
[22.6] What are interferons?
Proteins produced by lymphocytes, macrophages, and fibroblasts infected with a virus. Diffuse into uninfected cells to induce synthesis of antiviral proteins inhibiting viral replication.
[22.6] What is complement?
Inactive proteins in blood plasma that enhance immune reactions when activated. Typically cause cytolysis of microbes, promote phagocytosis, and contribute to inflammation.
[22.6] Describe iron-binding proteins in terms of immune responses.
Proteins binding iron to inhibit growth of bacteria by reducing available iron.
[22.6] Describe antimicrobial proteins.
Short peptides with a wide variety of antimicrobial activity as well as attracting dendritic cells and mast cells.
[22.6] What are natural killer cells?
Cells with the ability to kill a wide variety of infected and tumor cells, lacking membrane identity molecules
[22.6] Describe how natural killer cells carry out an immune response.
Natural killer cells bind to a target cell, triggering release of granules containing toxic substances typically using perforin or granzymes.
[22.6] What is perforin?
A protein that inserts into the plasma membrane of a target cell creating a channel through which extracellular flows into the cell. This causes cytolysis.
[22.6] What are granzymes?
Protein-digesting enzymes inducing apoptosis. Kills cells but not microbes within, leaving them for phagocytes.
[22.6] What are phagocytes?
Specialized cells performing phagocytosis.
[22.6] What are the major types of phagocytes?
Neutrophils and macrophages.
[22.6] What are wandering macrophages?
Macrophages that migrate to sites of infection.
[22.6] What are fixed macrophages?
Macrophages remaining in specific tissues.
[22.6] List the five stages of phagocytosis.
- Chemotaxis
- Adherence
- Ingestion
- Digestion
- Killing
[22.6] Describe the chemotaxis stage of phagocytosis.
Chemically stimulated movement of phagocytes to a site of damage.
[22.6] Describe the adherence stage of phagocytosis.
Attachment of phagocytes to microbes or foreign material.
[22.6] Describe the ingestion stage of phagocytosis.
The plasma membrane of the phagocyte extends projections that engulf a microbe, forming a phagosome around it.
[22.6] Describe the digestion stage of phagocytosis.
Phagosome enters the cytoplasm of phagocyte and merges with lysosomes. Lysosome introduce lysozyme which breaks down microbial cell walls as well as oxidants which burst the cell.
[22.6] Describe the killing stage of phagocytosis.
The chemical onslaught within phagolysosomes and the process of cell death of the microbe.
[22.6] Define inflammation.
A nonspecific defensive response of the body to tissue damage.
[22.6] What are the signs and symptoms of inflammation?
Pain, erythema, immobility, edema, heat.
[22.6] List the stages of inflammation.
- Vasodilation and increased blood vessel permeability
- Emigration of phagocytes
- Tissue repair
[22.6] Describe the vasodilation and increased blood vessel permeability stage of inflammation.
Vasodilation increases diameter of arterioles to promote blood flow, and increases permeability of capillaries to promote nutrient exchange.
[22.6] List substances that contribute to vasodilation.
- Histamine
- Kinins
- Prostaglandins
- Leukotrienes
- Complement
[22.6] Describe the emigration of phagocytes stage of inflammation.
Phagocytes are attracted to sites of injury through chemotaxis, squeezing through blood vessels to reach damaged tissue. Increase in blood vessel permeability helps facilitate this. Neutrophils respond first and die off quickly, followed by monocytes that transform into macrophages.
[22.6] What is leukocytosis?
An increase in white blood cells.
[22.6] What is pus?
A collection of dead cells and fluid.
[22.6] What is acute inflammation?
Rapid development of signs and symptoms that are typically resolved within a few days to weeks.
[22.6] What is chronic inflammation?
Slower development of signs and symptoms that can last months or years.
[22.6] What is fever?
Abnormally high body temperature induced by the hypothalamus either induced naturally or by bacterial toxins. Fever intensifies effect of interferons, inhibits growth of microbes, and promotes repair of tissue.
[22.7] What is adaptive immunity?
The ability of the body to defend itself against specific invasive agents.
[22.7] What are antigens?
Substances that provoke the immune responses, short for antibody generator.
[22.7] List and describe the properties that differentiate adaptive immunity from innate immunity.
- Specificity for particular foreign molecules
- Memory for previously encountered antigens prompting stronger responses.
[22.7] What are the lymphocytes involved in adaptive immunity?
B cells and T cells.
[22.7] Where do B and T cells develop and mature?
Both develop in red bone marrow.
B cells mature in bone marrow, T cells mature in the thymus.
[22.7] What is immunocompetence?
The ability to carry out adaptive immune responses.
[22.7] What are antigen receptors?
Proteins within the plasma membrane of immunocompetent cells capable of recognizing antigens.
[22.7] List the types of adaptive immunity.
- Cell-mediated immunity
- Antibody-mediated immunity
[22.7] What is cell-mediated immunity?
Cell-to-cell immunity carried out by cytotoxic T cells, mainly attacking intracellular pathogens, cancer cells, and foreign tissue.
[22.7] What is antibody-mediated immunity?
Cell-to-pathogen immunity carried out by B cells that have transformed into plasma cells, synthesizing and secreting antibodies. Mainly attacked extracellular pathogens.
[22.7] What are antibodies?
Specific protein binding molecules that inactivate specific antigens.
[22.7] What is clonal selection?
The process in which a lymphocyte proliferates and differentiates in response to an antigen.
[22.7] What is a clone cell?
An identical lymphocyte that emerges from clonal selection with the ability to recognize the same specific antigens.
[22.7] List the major types of cells produced by clonal selection.
- Effector
- Memory
[22.7] What is an effector cell in relation to immune cells?
Lymphocyte clones carrying out immune respones.
[22.7] List the types of effector cells and the cells they stem from.
- Active helper T cell; Helper T cell.
- Active cytotoxic T cell; Cytotoxic T cell
- Plasma cell; B cell
[22.7] What are memory cells?
Cells not participating in initial immune response but allow for a swifter and stronger response to antigens.
[22.7] List the types of memory cells and the cells they stem from.
- Memory helper T cells; Helper T cells.
- Memory cytotoxic T cells; Cytotoxic T cells
- Memory B cells; B cells.
[22.7] What is immunogenicity?
The ability to provoke an immune response by stimulating antibodies.
[22.7] What is reactivity with regards to immunity.
The ability of antigens to react specifically with antibodies or cells they provoke.
[22.7] What is a complete antigen?
Substances with both properties of immunogenicity and reactivity.
[22.7] What are epitopes?
Small parts of antigen molecules that act as triggers for immune responses.
[22.7] List the routes antigens follow into the lymphatic system.
- Trapped in the bloodstream as it flows through the spleen
- Penetrate skin defenses and enter lymphatic vessels/nodes
- Penetration of mucous membranes and subsequent trapping in MALT.
[22.7] What are haptens?
Smaller substances featuring reactivity but not immunogenicity. Can stimulate immune responses if bound to proteins.
[22.7] What is genetic recombination?
The process of shuffling and rearranging a few hundred versions of gene segments.
[22.7] What are major histocompatibility complex antigens?
Unique transmembrane glycoproteins assisting T cells in recognizing self vs foreign antigens.
[22.7] List and describe the classes of major histocompatibility complex antigens.
- Class I, molecules built into the plasma membranes. Featured in all cells except RBCs
- Class II, molecules on surface of antigen-presenting cells.
[22.7] What is antigen processing?
Process where antigen proteins are broken into peptide fragments that associate with MHC molecules. The antigen-MHC complex inserts into plasma membrane of a cell.
[22.7] What is antigen presentation?
The insertion of an MHC-antigen molecule into the plasma membrane of a cell. Causes reactions with foreign proteins, not from self-proteins.
[22.7] What are exogenous antigens?
Foreign antigens present in fluids outside body cells.
[22.7] What are antigen-presenting cells?
Cells that process and present exogenous antigens. Strategically located in areas likely to be exposed to antigens.
[22.7] Describe the first half of exogenous antigen processing and presenting.
- Antigen-presenting cells (APC) ingest exogenous agents.
- Protein-digesting enzymes within the APC split large antigens into peptide fragments.
- APC synthesizes and packages MHC-II molecules in ER
[22.7] Describe the second half of exogenous antigen processing and presenting.
- Vesicles containing antigen peptide fragments and MHC-II combine.
- Antigen peptide fragments bind to MHC-II.
- Antigen-MHC-II complex inserts into the plasma membrane.
[22.7] What are endogenous antigens?
Antigens present within body cells.
[22.7] Describe endogenous antigen processing and packaging.
- Antigen is digested into peptide fragments.
- MHC-I is synthesized in ER of body cell.
- Antigen peptide fragments and MHC-I bind within ER and are packaged.
- Antigen-MHC-I is inserted into the plasma membrane.
[22.7] What are cytokines?
Small protein hormones stimulating or inhibiting normal cell functions.
[22.8] What are T-cell receptors?
Antigen receptors on the surface of T cells recognizing and binding antigen fragments presented in antigen-MHC complexes.
[22.8] What are the auxiliary proteins of T cells aiding in antigen recognition?
CD4 and CD8.
[22.8] What is costimulation?
The process of activating a T cell involving receiving two signals simultaneously - the antigen-MHC and a protein costimulator.
[22.8] What is interleukin-2?
A cytokine costimulator for T cells.
[22.8] What is anergy?
A prolonged state of inactivity derived from binding of antigen-MHC but lacking a costimulator.
[22.8] What are helper T cells?
T cells displaying CD4 recognizing exogenous antigen fragments.
[22.8] Describe the response of helper T cells when activated.
CD4 acts as a costimulator when antigen-MHC complexes bind to plasma membrane. Helper T undergoes clonal selection and produced active helper T cells. The active cells secrete interluekine-2 and other cytokines.
[22.8] What are some actions of interleukin-2?
Acts as a costimulator for helper T, cytotoxic T, B, and natural killer cells.
[22.8] What are cytotoxic T cells?
T cells featuring CD8 protein in plasma membranes. Responds to exogenous antigens.
[22.8] What are the principal mechanisms for cytotoxic T cells when killing infected target cells?
- Release of granzymes that trigger apoptosis.
- Release of perforin and granulysin.
[22.8] Describe how perforin functions.
Inserts into plasma membrane of target cell and creates a channel allowing ECF to flow into the cytosol, triggering cytolysis.
[22.8] Describe how granulysin functions.
Enters a target cell through channels and creates holes in plasma membrane from within.
[22.8] What is lymphtoxin?
A molecule released by cytotoxic T cells, activating enzymes in target cell to fragment DNA.
[22.8] What are tumor antigens?
Novel cell surface components displayed by cancerous cells.
[22.8] what is immunological surveillance?
Immune responses carried out by cytotoxic T cells, macrophages, and NK cells that eliminate cancer cells displaying tumor antigens.
[22.9] What are B-cell receptors?
Integral transmembrane proteins chemically similar to antibodies, secreted by plasma cells.
[22.9] Describe the function of plasma cells.
Formed from clonal selection of B cells. After exposure to antigens, produces millions of antibodies per day until death, usually 4-5 days after initiation.
[22.9] What group of glycoproteins are antibodies considered?
Immunoglobulins.
[22.9] Describe the structure of antibodies.
Generally containing four polypeptide chains; two heavy chains containing 450 amino acids and two light chains containing 220 amino acids. Disulfide bonds attach heavy chains to light at a region termed the hinge region, and the portion of antibody composed of heavy chains is termed the stem region.
[22.9] List major actions of antibodies.
- Neutralizing antigens
- Immobilization of bacteria
- Agglutinating and precipitating antigens
- Activating complement
- Enhancing phagocytosis
[22.9] List the classes of immunoglobulins.
- IgG
- IgA
- IgM
- IgE
- IgD
[22.9] Describe IgG.
Most abundant, feature monomer structure. Enhances phagocytosis, neutralizes toxins, and triggers complement. Crosses placenta.
[22.9] Describe IgA
Second most abundant, found in glandular secretions. Occurs as monomer and dimer, protects against bacteria and viruses.
[22.9] Describe IgM
Third most abundant, occurs as a pentamer, first to be secreted by plasma cells. activates complement and causes agglutination and lysis of microbes. Also found as part of ABO antibodies.
[22.9] Describe IgE.
Monomer found on surface of B cell, involved in activation of B cells.
[22.9] Describe IgD.
Least abundant antibody, monomer located on mast cells and basophils. Functions in allergic and hypersensitivity reactions and protects against parasites.
[22.9] What is the complement system?
A defensive system comprised of over 30 proteins that destroy microbes through promotion of phagocytosis and inflammation. Typically function through cascade effect.
[22.9] List the steps of the cascade initiated by activation of C3.
- Inactive C3 splits into C3a and C3b.
- C3b binds to microbes and phagocytes, enhancing phagocytosis. This is known as opsonization.
- C3b initiates another cascade leading to a cylinder-shaped membrane attack complex.
- The membrane attack complex creates channels in microbes’ plasma membrane and induces cytolysis.
- C3a and C5a bind to mast cells and release histamine, increasing blood vessel permeability during inflammation.
[22.9] Describe the cascade triggered by C3b that leads to membrane attack complex.
C3b splits C5, leading to C5b. C5b binds to C6 and C7, attaching them to the plasma membrane of invading microbes. C8 and C9 begin binding and forms membrane attack complex.
[22.9] List the pathways of C3 activation.
- Classical pathway
- Alternative pathway
- Lectin pathway
[22.9] Describe the classical pathway of C3 activation.
Initiated by binding of antibodies to antigens. This action activates C1, which eventually activates C3. Very descriptive textbook.
[22.9] Describe the alternative pathway of C3 activation.
Initiated by lipid-carbohydrate complexes on surface of microbes interacting with complements B, D, and P.
[22.9] Describe the lectin pathway of C3 activation.
Macrophages digest microbes and release chemicals causing liver to produce lectin proteins. Lectins bind to carbohydrates on microbes and cause activation of C3.
[22.9] What is immunological memory?
The presence of long-lasting antibodies and long-lived lymphocytes that arise during clonal selection of antigen-stimulated B and T cells.
[22.9] What is an antibody titer?
The amount of antibody within serum.
[22.9] what is the primary response?
A slow rise in IgM antibody titer followed by a slow rise in IgG antibody titer occurring several days after initial contact with an antigen.
[22.9] What is the secondary response?
An intense accelerated response subsequent of primary responses showing larger flux in IgM and IgG antibody titer.
[22.10] List the two traits necessary for proper function of T cells.
- Self-recognition: ability to recognize self MHC proteins.
- Self-tolerance: inability to react to peptide fragment of self-proteins.
[22.10] How are autoimmune diseases developed?
A loss in self-tolerance of either T or B cells.
[22.10] What is positive selection?
The development of the capacity for self-recognition in pre-T cells in the thymus. Involves selecting pre-T cells interacting with self-MHC proteins to survive, and initiating apoptosis in pre-T cells that do not interact with self-MHC.
[22.10] What is negative selection?
The development of self-tolerance of T cells within the thymus, where T cells that react to self-peptide fragments are eliminated.
