Download LEARNING OBJECTIVE 1: Describe the general functions of the

CHAPTER 16
LYMPHATIC SYSTEM AND IMMUNITY
LEARNING OBJECTIVE 1: Describe the general functions of the lymphatic system.
and
LEARNING OBJECTIVE 2: Identify the locations of the major lymphatic pathways.
Lecture Suggestions and Guidelines
1. Introduce the lymphatic system and its association with the cardiovascular system.
2. Describe the lymphatic pathways, including a discussion of lymphatic capillaries, vessels, trunks, and collecting
ducts.
3. Discuss the role of lymph nodes.
4. Describe the location and function of the right lymphatic duct and the thoracic duct.
Application Question(s)
1. Ask students to label a diagram of the human body with the locations of the major lymphatic trunks and
collecting ducts.
Answer: The diagram should include the jugular trunk, subclavian trunk, bronchomediastinal trunk, intercostal
trunk, intestinal trunk, lumbar trunk, right lymphatic duct, and the thoracic duct.
Critical Thinking Issue(s)
1. Discuss the purpose of tonsils. What causes tonsillitis?
Answer: The tonsils are a form of lymph tissue, which filters bacteria and destroys them through phagocytosis.
Frequently, the streptococcal organisms cause the tonsils to become infected and irritated. This may lead to a
narrowing of the passageway for swallowing, fever, and leukocytosis. The treatment of choice is antibiotics. An
untreated streptococcal infection is potentially dangerous.
LEARNING OBJECTIVE 3: Describe how tissue fluid and lymph form and explain the function of
lymph.
and
LEARNING OBJECTIVE 4: Explain how lymphatic circulation is maintained and describe the
consequence of lymphatic obstruction.
Lecture Suggestions and Guidelines
1.
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6.
Review the processes of diffusion and filtration.
Discuss tissue fluid formation and osmotic pressure.
Describe lymph formation and function.
Describe the function of flaplike valves in the lymphatic capillary wall.
Discuss methods employed to insure lymph movement and flow.
Give examples of conditions, which may lead to an obstruction of lymph movement.
Application Question(s)
1. Apply the information provided by this learning objective to develop a flowchart depicting the lymphatic
pathway.
Answer: The flowchart should include lymphatic capillaries, lymphatic vessels, lymph nodes, lymphatic trunk,
collecting duct, and the subclavian vein.
Critical Thinking Issue(s)
1. Discuss elephantiasis.
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Answer: Elephantiasis is a disease of the lymphatic system in which the lymphatic vessels are blocked by
parasitic worms. The blockage will not allow the lymph to circulate properly, causing severe edema, primarily
in the extremities. Although relatively uncommon, the disease can be debilitating and painful.
LEARNING OBJECTIVE 5: Describe a lymph node and its major functions.
and
LEARNING OBJECTIVE 6: Describe the location of the major chains of lymph nodes.
Lecture Suggestions and Guidelines
1.
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3.
4.
Discuss the structure of a lymph node, including the hilum, nodules, and lymph sinuses.
Review the terms afferent and efferent.
Describe the tonsils and Peyer’s patches.
Discuss the major functions of lymph nodes and give examples of seven major lymph node locations.
Application Question(s)
1. Provide the following terms to students: trabecula, subcapsule, sinus capsule, germinal center, nodule, medulla,
and hilum. Ask students to sketch a lymph node and apply these terms to it.
Critical Thinking Issue(s)
1. Under what conditions might lymph nodes be swollen, but not painful?
Answer: Responses should include a discussion of cancer. Some cancers utilize lymphatic vessels for
transportation throughout the body.
LEARNING OBJECTIVE 7: Discuss the functions of the thymus and spleen.
Lecture Suggestions and Guidelines
1.
2.
3.
4.
Introduce the general anatomy, physiology, and location of the thymus and spleen.
Briefly describe the role of lymphocytes in providing immunity.
Review the role of thymosin.
Describe the spleen in terms of red pulp and white pulp, and its association with macrophages and lymphocytes.
Application Question(s)
1. Compare and contrast the functions of the spleen and thymus.
Answer: Both the spleen and thymus are lymphoid organs. The spleen synthesizes lymphocytes, the thymus
produces hormones which help program the lymphocytes to perform certain functions. The spleen filters blood,
unlike lymph nodes, which filter lymph. Both spleen and thymus contain reticular connective tissue and
lymphocytes.
Critical Thinking Issue(s)
1. Discuss a condition in which removal of the spleen may be beneficial.
Answer: Lecture on various types of hemolytic anemias. A congenital form, in which the red blood cells are
vulnerable to excessive hemolysis by the spleen, is one example.
LEARNING OBJECTIVE 8: Distinguish between specific and nonspecific defenses, and provide
examples of each.
Lecture Suggestions and Guidelines
1. Describe various examples of nonspecific defense mechanisms. Include a discussion of species resistance,
mechanical barriers, chemical barriers, fever, inflammation, and phagocytosis.
2. Introduce the concept of specific immunity. More detailed information will be discussed in meeting subsequent
learning objectives.
3. Summarize the major actions that may occur during an inflammation response.
4. Define the terms interferon, pyrogen, and macrophage.
5. Discuss various types of infections.
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Application Question(s)
1. Ask students to prepare a chart, which summarizes nonspecific body defenses. Include specific examples of
each type.
Answer: Types of nonspecific defenses include species resistance, mechanical barriers, chemical barriers,
fever, inflammation, and phagocytosis. Specific examples of each will vary.
Critical Thinking Issue(s)
1. Discuss the nonspecific defense mechanisms, which would be activated and violated following a situation in
which a barefoot child has stepped on a rusty nail, which pierced the skin.
Answer: Responses will vary, but should employ several nonspecific defense mechanisms.
LEARNING OBJECTIVE 9: Explain how two major types of lymphocytes are formed, activated, and
how they function in immune mechanisms.
Lecture Suggestions and Guidelines
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Discuss the origins of lymphocytes and specialization into B cells and T cells.
Describe the term antigen and give several examples.
Define hapten.
Distinguish between cell-mediated immunity and antibody-mediated immunity.
Define cytokines.
Discuss the general functions of lymphocytes and lymphocyte clones.
Describe the process of B cell activation and the polyclonal response.
Application Question(s)
1. Ask students to develop a table which compares T cells and B cells.
Answer: The table should describe differences between humoral and cell-mediated immunity, origin of
undifferentiated cells, site of differentiation, and primary locations. T cells can further be subcategorized as
helper T cells, killer T cells, and suppressor T cells.
Critical Thinking Issue(s)
1. Ask students to prepare a short report about the interrelationship between T cells and AIDS. Which type of T
cell provides a prime target for AIDS?
Answer: Discussion should lead to a description of the role of the cluster-of-differentiation antigen.
LEARNING OBJECTIVE 10: Name the major types of immunoglobulins and discuss their origins and
actions.
Lecture Suggestions and Guidelines
1. Introduce the five major types of immunoglobulins. Describe each name, occurrence, and major function.
2. Describe the role of complement.
3. Discuss the actions of antibodies.
Application Question(s)
1. Provide students with a drawing of each of the five major immunoglobulins. Have them identify each by name,
give the location where each would be found in the body, and give a description of their biological functions.
Answer: Responses should include a discussion and identification of IgD, IgM, IgG, IgA, and IgE.
Critical Thinking Issue(s)
1. Ask students to investigate the sequence of complement activation in more detail.
Answer: The sequence of complement fixation involves nine separate proteins. An antigen-antibody complex
activates C1, which creates a complex that activates C4 and C2, creating a complex which activates C3,
creating a complex which activates C567, creating a complex which activates C89, which will finally result in
the punching of holes in foreign cell membranes.
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LEARNING OBJECTIVE 11: Distinguish between primary and secondary immune responses.
Lecture Suggestions and Guidelines
1. Describe the events which occur when B cells or T cells first encounter an antigen.
2. Define memory cells.
3. Explain the occurrence of a secondary immune response.
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Application Question(s)
1. What sequence of events occurs after a macrophage digests antigen-bearing agents?
Answer: Students may develop a flowchart of events, including the activation of helper T cells, T cell
interaction with B cells, binding of macrophages to lymphocytes, and the triggering of other immune defenses.
Critical Thinking Issue(s)
1. Ask students to illustrate the proliferation of activated B cells, which give rise to plasma cells and memory
cells.
Answer: Illustrations will vary.
LEARNING OBJECTIVE 12: Distinguish between active and passive immunity.
Lecture Suggestions and Guidelines
1. Discuss active immunity. Distinguish between naturally-acquired and artificially-acquired active immunity.
Give examples of each.
2. Describe passive immunity. Distinguish between naturally-acquired and artificially-acquired passive immunity.
Give examples of each.
3. Define the term vaccine.
4. Discuss the competence of the immune system with advancing age.
Application Question(s)
1. What are some examples of active and passive naturally acquired immunity?
Answer: Examples of naturally acquired active immunity might be infection caused by a pathogenic organism.
Antibodies crossing the placenta from mother to fetus would be an example of naturally acquired passive
immunity.
Critical Thinking Issue(s)
1. Discuss the advantages of receiving a vaccine.
Answer: Responses will probably include a discussion of protection from disease, i.e., we would not be
required to suffer through the signs and symptoms activated by a primary response. Also, booster shots
facilitate antibody production and memory.
LEARNING OBJECTIVE 13: Explain how allergic reactions, tissue rejection reactions, and
autoimmunity arise from immune mechanisms.
Lecture Suggestions and Guidelines
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Describe allergic or hypersensitivity reactions.
Define a delayed-action allergy.
Discuss anaphylactic shock.
Discuss tissue rejection reactions and their similarity to cell-mediated responses.
Describe four major types of grafts. Give examples of each.
Define autoimmunity and describe a variety of autoimmune disorders.
Application Question(s)
1. What is graft-versus-host disease?
Answer: Graft-versus-host disease is a common concern during bone marrow transplantation. The recipient’s
cells are sometimes mistaken as foreign, and are attacked by the donor’s lymphocytes. This disease is often
fatal, causing remarkable changes in the liver, intestine, and skin.
Critical Thinking Issue(s)
1. Ask students to research a major autoimmune disease. The report should include a definition of the disease, the
antigen involved, the manifestations, signs and symptoms, course, outcome, prognosis, and survival rate of the
disease.
Answer: Some examples include autoimmune hemolytic anemia, myasthenia gravis, rheumatic heart disease,
systemic lupus erythematosus, and rheumatoid arthritis.
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LEARNING OBJECTIVE 14: Describe life-span changes in immunity.
Lecture Suggestions and Guidelines
1. Describe the general changes in the immune system.
2. Discuss the effects of aging on the declining strength of the immune response.
3. Identify the shift in various antibody classes.
Application Question(s)
1. Ask students to identify the changes in the immune system that occur with AIDS.
Answer: Discussion should include opportunism, symptoms, structure of the virus, effects on helper T-cells, etc.
Critical Thinking Issue(s)
1. Compare and contrast various methods being researched to combat AIDS.
Answer: Responses may include an analysis of various drugs and a discussion of receptor molecules.
RELATED DISEASES OF HOMEOSTATIC INSTABILITY
1. Infectious Mononucleosis—A viral infection caused by the Epstein-Barr virus. It is commonly referred to as
“mono,” “the kissing disease,” or “the college disease.” An increased appearance of atypical lymphocytes is
present. Signs and symptoms include fever, fatigue, sore throat, and swollen lymph nodes. The major treatment
is bed rest.
2. Hodgkin’s Disease—The most common type of lymphoma. It is malignant in nature and appears to be of viral
or infectious origin. Symptoms include painless lymph nodes, nonspecific malaise, fever, weight loss, itching of
skin, and the presence of large, atypical macrophages. Remission is common.
3. Anaphylaxis—A hypersensitivity reaction influenced by IgE antibodies. The reaction may be localized (rash,
wheals, or hives) or systemic. The systemic version is more severe and may include a drop in blood pressure
and an inability to breathe.
SUGGESTIONS FOR ADDITIONAL READING
Baltimore, David. January 26, 1995. Lessons from people with nonprogressive HIV infection. New England Journal
of Medicine, vol. 332. A small percentage of people infected with HIV for more than a decade have not become
ill—why? This issue of the journal contains several articles on long-term survivors of AIDS.
Diamond, Jared. September 1992. The mysterious origin of AIDS. Natural History. Did the AIDS epidemic begin
because of a single mutation in a virus or as a terrible side effect of vaccine research decades ago? Or has AIDS
been around for a long time, but simply gone unnoticed among the infections common in some societies?
Fields, Bernard N. May 12, 1994. AIDS: Time to turn to basic science. Nature, vol. 369. Understanding the
interactions between HIV and the human immune system will help us develop treatments and a vaccine.
Johnson, Howard M. et al. May 1994. How interferons fight disease. Scientific American. They are not the cure-all
researchers once hoped they would be, but they are providing therapy for a variety of infectious illnesses and for
some cancers.
Landry, Donald W. February 1997. Immunotherapy for Cocaine Addiction. Scientific American.
Lewis, Ricki. July 1991. Joint attack: Arthritis. FDA Consumer. Rheumatoid arthritis is an autoimmune disorder.
Lowenstein, Jerold M. June 1993. The transplant gap. Discover. We humans don’t supply enough organs for
transplant. Can animals solve our problem?
McIntosh, K. And S.K. Burchett. March 30, 1995. Clearance of HIV-lessons from newborns. New England Journal
of Medicine, vol. 332. At first, researchers thought that babies with HIV infection who became free of the virus
reflected laboratory errors—that is, they had never really been infected. They were wrong. This is the first
official report of such a child—his recovery may help us beat AIDS.
Murray, Joseph E. June 5, 1992. Human organ transplantation: Background and consequences. Science, vol. 256. An
extensive and fascinating review of the development of transplantation medicine.
Nowak, Rachel. December 17, 1993. ‘‘Bubble boy’’ paradox resolved. Science, vol. 262. SCID is sometimes caused
by defective cytokine receptors.
Old, Lloyd J. September 1996. Immunotherapy for Cancer. Scientific American.
Sanfilippo, Fred. September 22, 1994. HLA matching in renal transplantation. New England Journal of Medicine,
vol. 331. The closer the HLA match, the more likely a kidney transplant is to succeed.
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Short, Nicholas. February 1995. A fight to the death. Nature Medicine, vol. 1. HIV reproduces so rapidly that it is
only a matter of time until it overwhelms the human immune system.
Wain-Hobson, Simon. January 12, 1995. Virological mayhem. Nature, vol. 373. HIV infection spirals out of control
much sooner than we had thought.
Winter, Greg and Cesar Milstein. January 24, 1991. Man-made antibodies. Nature, vol. 349. Genetic engineering can
provide antibodies not seen in nature.
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