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Chapter 21 LO � Lymphatic system and immunity
disease producing organism
present at birth, provides rapid response against disease
Occurs more slowly & develops in response to specific pathogens
Distinguishing between interstitial fluid and lymph
interstitial fluid is located in the space surrounding the cells, lymph is located in the lymphatic vessels
Describing the composition of lymphatic tissue
Reticular connective tissue containing lymphocytes
Describing the functions of the lymphatic system
Drains excess interstitial fluid, Transport dietary lipids from the gastrointestinal tract to the blood and protect against invasion through immune responses. thymus, lymph nodes, and spleen
Describe lymphatic capillaries.
Lymphatic capillaries are closed at one end by overlapping endothelial cells that form their wall. They unite to form lymphatic vessels but they differ by having thin walls and more valves. Anchoring filaments are attached to the lymphatic capillaries and pull the endothelial cells apart when edema is present to enlarge the openings and allow the interstitial fluid to flow inside the lymphatic capillaries.
Describe the sequence of lymphatic structures a drop of lymph encounters from the time it leaves the interstitial spaces until it reaches venous blood (the exam will not ask about lymphatic trunks).
Interstitial Space --> Lymphatic Capillaries --> Lymphatic Vessels --> Lymph Nodes --> More Lymphatic Vessels� --> Lymphatic Ducts --> Venous Blood
which vessels lymph enters venous blood
- The thoracic duct drains into the left brachiocephalic v., near the junction of the left internal jugular v. and left subclavian v.
- The right lymphatic duct drains into the right brachiocephalic v., near the junction of the right internal jugular v. and right subclavian v.
Explain how skeletal muscle contractions and breathing help maintain the flow of lymph.
Skeletal muscle contractions-- a "milking" action that forces lymph to internal jugular & subclavian veins Breathing-- maintained by pressure changes from inhaling & exhaling; valves prevent backflow
LO 6: Naming the organs of the lymphatic system
Thymus, lymph nodes, spleen and red bone marrow. Lymphatic nodules are tissues not organs.
LO 6: Describing the flow of lymph through a lymph node
Afferent lymphatic vessel--->Subcapsular sinus---->Trabecular sinus---> Medullary sinus--->Efferent lymphatic vessel.
Stating two examples of lymphatic tissue in the gastrointestinal tract
- Peyer's patches (lymphatic nodules) in the ileum
- Palatine tonsils in the back of the oral cavity.
LO 7: Describe the physical and chemical barriers that form the first line of defense against pathogens and foreign substances.
- Physical: skin, hair, mucus, cilia, flow of urine
- Chemical: saliva, sebum, lysozyme, tears, vaginal secretions, gastric juices
LO8: State the source and function of interferons.
- Source: body cells infected with a virus produce interferons.
- Function: KISS: prevent spreading of the virus to unaffected body cells.
- (non-KISS: stimulate antiviral proteins in neighboring uneffected cells by diffusing into them to block viral replication)
LO 9: Describe the function of natural killer cells.
NK cells kill cells that are infected with intracellular pathogens, they are members of innate immunity and act in non-specific manner. They produce perforin and granzymes, resulting in cytolysis and apoptosis, respectively.
LO 9:Cytolysis is:
when a cell bursts due to being hypertonic to its environment. In cytolysis, the high osmalarity within the cell draws in more water than the cell membrane can contain and the cell bursts, spilling all of its contents out into its environment. The spilled cellular debris may be damaging to nearby cells.
LO 9:Apoptosis is:
a type of programmed cell death, or "cell suicide," that may be activated by the addition or removal of certain chemicals to or from the cell. The process of apoptosis includes changes to cellular DNA. Apoptosis results in the cell dying and being split into apoptotic fragments. The formation of apoptotic fragments are less damaging to nearby cells and more easily engulfed by phagocytes.
LO 10:Two major types of phagocytes:
LO 10:Origin of macrophages
LO 10:Function of phagocytes
ingest and destroy microbes, cell debris, and other foreign matter.
LO 10: Where do Macrophages come from?
- They do not originate from Thymus, they are derived from monocytes after migration to infected/inflammed tissues. Monocytes are found circulating in the blood
- stream and the monocyte precursors come from the red bone marrow.
LO 11:State the conditions that can produce inflammation:
- extremely cold and hot temperatures
- cellular damage
- invasion by pathogens
- certain chemicals
LO 11: Stating the signs and symptoms of inflammation
LO 11:Stating the beneficial purpose of inflammation
- promotion of healing by tissue repair
- disposal of pathogens
- limiting their spread to distal sites
LO 11:Describing the inflammatory response (the exam will not ask the names of specific inflammatory substances)
- Vasodilation and increased vascular permeability
- Phagocytic cell emigration
- Chemotaxis and pathogen killing
LO 11:Define pus:
The liquid product of inflammation containing leukocytes or their remains and debris of dead cells.
LO 11:Explaining the cause of each of the signs and symptoms of inflammation
- Heat: increased flow of blood and higher metabolism at the site of inflammation
- Redness: dilated arterioles allow large amounts of
- blood to accumulate at the injured site
- Pain: injured neurons, released microbial toxic substances, pressure of edema
- Edema: increased vascular permeabilization
LO 12: Define abscess.
a localized collection of pus and liquefied tissue in a cavity.
LO 13: Explain how a mild fever can benefit your body.
- Increasing interferons' effects
- Directly inhibits the growth of some microbes
- Speeds up the body's reactions that aid in repair.
LO 14: Defining adaptive immunity
The body's learned defense activities against specific pathogens and antigens
LO 14: Stating two properties that distinguish adaptive immunity from innate immunity
Specificity and Immunological Memory
LO 14: Defining immunocompetence
The capacity to develop an immune response following exposure to an antigen.
LO 14: Distinguishing between B and T lymphocytes with regard to their origin, maturation into immunocompetent cells, and general function
- Both B & T Cells originate from pleuripotent stem cells and lymphoblasts in red bone marrow.
- B cells finish maturation and acquisition of immunocompetence in the red bone marrow. When reacting with a foreign antigen, they become plasma cells, which produce antibodies.
- T Cells finish maturation and acquisition of immunocompetence in the thymus. When T cells react with a foreign antigen they clone and activate B Cells and cytotoxic T cells. Memory T cells are also produced.
LO 14: Distinguish between cell-mediated immunity and antibody-mediated immunity
In antibody-mediated immunity, antibodies are produced and secreted (by activated B cells) into the extracellular fluid to encounter their specific antigens.
LO 14: Defining antibodies
Antibodies or immunoglobulins are certain specific proteins that are produced in response to specific antigens and are capable of inactivating it.
LO 14: Describing antigens
foreign substances that trigger an immune response.
LO 15: Define autoimmune disease
when the immune system fails to tolerate and attacks the body's own tissue.
LO 15: Briefly explain how autoimmune disease can occur
- Immune system turns against itself, can not distinguish what are foreign anitgens and itself.
- Production of antibodies and Tc Cells that destroy its own tissue
LO 15: Describe two autoimmune diseases:
- Multiple Sclerosis: white matter of the brain and spinal cord is destroyed
- Grave's Disease: Thyroid gland overproduces thryoxine
- Rheumatoid arthritis: systematic destruction of joints
- Type I Diabetes mellitus: destruction of pancreatic beta cells which results in a deficit of insulin and inability to use carbohydrates
LO 16: Describe the role of antigen-presenting cells.
APC's present T cells with the digested antigens, invoking the immune response and production of antibodies specific to the presented antigens. Antigen-presenting cells (APC's) digest and process pathogens. They are a special class of migratory cell that processes and presents antigens to T cells during an immune response.
LO 17: Summarize the functions of helper T cells
- cooperates with B cells to amplify antibody production by plasma cells and secretes interleukin-2, which stimulates proliferation of T cells and B cells.
- KISS: increases production of antibodies, T cells and B cells.
LO 17: Summarize the functions of cytotoxic T cells.
- kill host target cells by releasing granzymes that induce apoptosis, perforin that forms channels to cause cytolysis, granulysin that destroys microbes and lymphotoxin that destroys target cell DNA.
- KISS: Kills target cells including microbes by stopping target cell internal activity resulting in cell death or by stopping cellular replication.
LO 18: Define AIDS and state its full name.
Aquired immunodeficiency syndrome
LO 18: Name the virus that produces AIDS.
Human immunodeficiency virus (HIV) produces AIDS.
LO 18: Explain how AIDS is transmitted.
Since HIV is present in the blood and some body fluids, it is most effectively transmitted by actions or practices that involve the exchange of blood or body fluids between people.
LO 18: State which immune system cells are attacked by the AIDS virus.
Helper T Cells
LO 19: B cell activation, proliferation, and differentiation:
LO 19: Plasma cells:
Secrete a lot of antibodies each day (starting after few days of exposure) for 4 to 5 days until they die. After activation of a B cell, a clone of plasma cells and memory B cells are formed. Plasma cells secrete specific antibodies.
LO 19: Memory cells:
Are not involved in the initial immune response against an invading pathogen, they have very long lifespan and linger on in circulation well after the pathogen has been dealt with. If the same pathogen invades again, the memory cells much more rapidly initiate an immune response.
LO 19: The actions of antibodies:
- Neutralizing antigen: Antibodies bind with its antigen to neutralize bacterial toxins and prevent attachment to body cells.
- Immobilizing bacteria: Antibodies disable bacteria motility, which limits their spread.
- Agglutinating and precipitating antigen: Since antibodies have two antigen binding sites, the antigen-antibody reaction connects pathogens to one another, causing agglutination. Phagocytic cells ingest agglutinated microbes more readily.
- Activating complement: Antigen-antibody complexes activate complement protein.
- Enhancing phagocytosis: Antibodies attract phagocytes to antigens they bind to. Antibodies enhance the activity of phagocytes by causing agglutination, by activating complement, and by coating microbes so that they are more susceptible to phagocytosis.
LO 20: Define allergic reactions:
A hypersensitivity reaction brought on by an allergen's exposure to a foreign substance.
LO 20: Define allergen:
An antigen that evokes a hypersensitivity reaction.
LO 20: Define infectious mononucleosis:
- A disease caused by Epstein-Barr Virus infecting B Cells.
- Transmitted from person to person by oral contact(a.k.a. kissing disease)
- characterized by fatigue ,dizziness,headache,sore throat,fever and enlarged and painful lymph nodes.
- Monocytes are not infected in mononucleosis. The infected B cells, however, become enlarged and atypical to the point that they appear similar to monocytes.
LO 21: Define monoclonal antibodies and list the diagnostic uses of monoclonal antibodies.
- MAbs are numerous identical antibodies that spring from the cloning of identical cells.
- Diagnostic uses of monoclonal antibodies include: strep throat, pregnancy, allergies, hepatitis, rabies and some sexually transmitted diseases. Also, MAbs can be used to detect cancer at an early stage.
LO 22: Explain the immune-response of the spleen:
- Stores some of the breakdown products of red blood cells for later resuse and releases others to the blood for processing by the liver
- A site of erythrocyte production in the fetus
- Stores blood platelets
LO 22: Explain the immune-response of lymph nodes-
- Act as lymph "filters": marcophages remove and destroy microogranisms and other debris that enter the lymph from the loose connective tissue
- Help activate the immune system: lymphocyctes monitor the lymphatic stream for the presence of antigens and when there is some present they mount an attack against them.
LO 22:Explain the immune-response of the tonsils:
effectively positioned lymphatic nodules near the possible entry of microbes into the body (Nasopharynx, tongue). They trap the pathogens as they are being inhaled or ingested. (Pharyngeal, Palatine, Lingual tonsils)
Define the complement system:
The complement system includes a group of more than 30 proteins that are made in the liver and are circulating in the blood plasma and within the tissues in the whole body.
Explain complement's three functions [also see Table 21.1 in text]:
- Enhances phagocytosis by coating microbes with C3b.
- Cytolysis: bursting of microbe due to inflow of extracellular fluid through channel formed by membrane attack complex C5-C9.
- Inflammation: Increases blood vessel permeability and chemotactic attraction of phagocytes.
Describe immunological memory:
The immune system's ability to retain memory of the specific antigens that have triggered a previous response. Immunological memory exists due to the presence of long lasting antibodies and lymphocytes that are in the immune system during clonal selection of antigen-stimulated B cell and T cells.
Describe the primary response:
Is triggered by the first exposure to an antigen, this is a slow rise in antibody titer several days after exposure, followed by a gradual decline.
Describe the secondary response:
The accelerated response to an antigen after a subsequent exposure is caused by memory B cells and memory T cells that remain in the body.
Vaccinations of weakened or killed whole microbes or portions of microbes trigger a primary response so in the future if you encounter live microbes the much quicker secondary response will be initiated.
AGGREGATED LYMPHATIC NODULES:
are not LYMPHATIC ORGANS. Instead, they are simple masses of lymphatic tissue found within the walls of the small intestine and the appendix,
- another form of lymphatic nodules. The tonsils form a ring of lymphatic tissue around the entrance to the pharynx (throat), where they appear as swellings of
- the mucosa.
- The paired PALATINE TONSILS are located on either side of the posterior end of the oral cavity.
- The LINGUAL TONSILS are a lumpy collection of lymphoid follicles at the base of the tongue.
- The PHARYNGEAL TONSIL (referred to as the “adenoids” when enlarged) is imbedded in the posterior wall of the nasopharynx (upper throat in back of the nose). In these strategic locations, tonsils trap and phagocytize many of the pathogens entering the pharynx within food or inhaled air.
Right lymphatic duct
Afferent lymphatic vessels
Efferent lymphatic vessels