The lymphatic system consists of lymphatic vessels andlymphoid organs. The lymphatic vessels absorb fat mol-ecules at intestinal villi and excess tissue fluid at the car-diovascular capillaries. Eventually, two main ducts emptyinto the subclavian veins.

Lymphocytes are produced and accumulate in thelymphoid organs (lymph nodes, spleen, thymus gland,and red bone marrow).

Immunity involves nonspecific and specific de-fenses. Nonspecific defenses include barriers to entry,the inflammatory reaction, and protective proteins.

Specific defenses require lymphocytes, which areproduced in the bone marrow. B lymphocytes mature inthe bone marrow and undergo clonal selection in thelymph nodes and the spleen. T lymphocytes mature inthe thymus.

B cells are responsible for antibody-mediated im-munity. An antibody is a Y-shaped molecule that has twobinding sites. Each antibody is specific for a particularantigen. Activated B cells become antibody secretingplasma cells and memory B cells. Memory B cells respondif the same antigen enters the body at a later date.

There are four types of T cells. Cytotoxic T cellskill cells on contact; helper T cells stimulate other immune

cells and produce lymphokines; suppressor T cells sup-press the immune response; and memory T cells remainin the body to provide long lasting immunity.

Immunity can be induced in various ways. Vac-cines are available to promote long lived active immu-nity, and antibodies sometimes are available to providean individual with short lived passive immunity.

Cytokines, notably interferon and interleukins, areused in an attempt to promote the body’s ability to recoverfrom cancer and to treat AIDS.

Blood transfusions require compatible blood types.Of consideration are the antigens (A and B) on the red bloodcells and the antibodies (anti-A and anti-B) in the plasma.The Rh antigen is also important particularly because anRh-negative mother may produce anti-Rh antibodies thatwill attack the red blood cells of an Rh-positive fetus.

Allergies result when an overactive immune systemforms antibodies to substances not normally recognizedas foreign. Cytotoxic T cells attack transplanted organsas nonself; therefore, immunosuppressive drugs must beadministered. Autoimmune illnesses occur when antibodiesand T cells attack the body’s own tissues.

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14LYMPHATIC SYSTEM AND IMMUNITY

CHAPTER REVIEW

STUDY EXERCISES

Study the text section by section as you answer the questions that follow.

14.1 LYMPHATIC SYSTEM (P. 264)

• The lymphatic vessels form a one-way system, which transports lymph from the tissues and fat from thelacteals to certain cardiovascular veins.

• The lymphoid organs (red bone marrow, spleen, thymus, and lymph nodes) play critical roles in defensemechanisms.

1. Give three functions of the lymphatic system.a.

b.

c.

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2. Indicate whether the following statements about the structure/function of lymphatic vessels and lymphoidorgans are true (T) or false (F):

a. Bone marrow lacks lymphoid tissue.b. Lymph lobules are subdivided into sinus-containing nodes.c. The contraction of skeletal muscles blocks the return of lymph to the bloodstream.d. The sinuses of the spleen are filled with lymph.e. Lymphatic vessels are similar to systemic veins.f. Lymphatic vessels contain valves.

3. Indicate whether the statements that follow are true (T) or false (F). Rewrite any false statements to makethem true.

a. Vessels of the lymphatic system begin with systemic capillaries. Rewrite: _____________________b. Lymph most closely resembles arterial blood. Rewrite: ____________________________________

_____ c. The right thoracic duct serves the lower extremities, abdomen, one arm, and one side of the head andneck. Rewrite: ____________________________________________________________________

d. Lymphatic capillaries merge directly to form a particular lymphatic duct. Rewrite: _______________________________________________________________________________________________

4. Label each of the following statements as describing the thymus (T), spleen (S), or red bone marrow (RBM):a. contains red pulp and white pulpb. contains stem cellsc. is located along the trachead. is located in the upper left abdominal cavitye. produces hormones believed to stimulate the immune systemf. contains sinuses filled with bloodg. site of origin for all types of blood cells

14.2 NONSPECIFIC DEFENSES (P. 266)

• Immunity consists of nonspecific and specific defenses to protect the body against disease.• Nonspecific defenses consist of barriers to entry, the inflammatory reaction, natural killer cells, and

protective proteins.

5. Match each of the descriptions with the following defense mechanisms:1 barrier to entry2 inflammatory response3 complement protein4 natural killer cells

a. accompanied by swelling and rednessb. cilia action in the respiratory tractc. produces holes in bacterial cell wallsd. stomach secretionse. histamine increases capillary permeabilityf. injured cells release bradykining. inhabitation of normal body bacteriah. interferon actioni. neutrophils and macrophages carry out phagocytosisj. secretions of the oil, or sebaceous, glandsk. kills cells infected with a virus or tumor cells

14.3 SPECIFIC DEFENSES (P. 268)

• Specific defenses require two types of lymphocytes: B lymphocytes and T lymphocytes.

6. Fill in this table with yes or no:

Cytotoxic T Cell B Cell

Ultimately derived from stem cells in bone marrow a. b.

Pass through thymus c. d.

Carry receptors on membrane e. f.

Cell-mediated immunity g. h.

Antibody-mediated immunity i. j.

B Cells and Antibody-Mediated Immunity (p. 269)

Study the diagram and answer questions 7–10.7. Which of these makes a particular B cell undergo clonal expansion?

a. When the correct antigen is present.b. When; any antigen is present

8. Explain the clonal selection theory. _________________________________________________________________

_________________________________________________________________________________________________

9. Which of these are cells that result from clonal expansion of B cells?a. plasma cellsb. memory cellsc. both types of cells.

10. What happens to these cells once the infection is under control?

a. memory cells ___________________________________________________________________________________

b. plasma cells ____________________________________________________________________________________

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antigenreceptor

antigens

Activation ApoptosisClonal Expansion

antibodies

memory cells

plasma cells

endoplasmicreticulum

B lymphocytes

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11. a. Label this diagram of an antibody molecule with the following terms: antigen-binding site, constant region,heavy chain, light chain, and variable region.

What is the function of antibodies? b._______________________

T Cells and Cell-Mediated Immunity (p.272)

Activation Activated T cells

T lymphocytes

cytotoxicT cell

antigenreceptor

self protein (HLA)presents an antigen

virus-infected cell

memory cells

Apoptosis

Clonal Expansion

cytokines

cytokines

Study the diagram and answer questions 12–14.12. Which of these makes a particular T cell under go clonal expansion?

a. When the antigen is presented to the T cells by an APC.b. When a T cell encounters an antigen.

13. What is the significance of HLA antigens? a. __________________________________________________________

_________________________________________________________________________________________________

Why are they called antigens? b. _____________________________________________________________________

_________________________________________________________________________________________________

14. What happens after a helper T cell recognizes an antigen? a. ____________________________________________

_________________________________________________________________________________________________

What happens after a cytotoxic T cell recognizes an antigen? b. __________________________________________

_________________________________________________________________________________________________

What happens to T cells (except for memory T cells) after the infection is past? c. _________________________

_________________________________________________________________________________________________

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14.4 INDUCED IMMUNITY (P. 274)

• Induced immunity for medical purposes involves the use of vaccines to achieve long-lasting immunity and theuse of antibodies to provide temporary immunity.

15. a. Label the following diagram, using the alphabetized list of terms.antibody titer in serumprimary response,secondary responsetime (days)exposure to vaccine (needed twice)

b. A good secondary response can be related to the ________________________ dependent on the number of

________________________ and ________________________ cells capable of responding to a particular antigen.

16. When an individual receives antibodies from another, as when a baby breast-feeds, it is called ___________________.

17. List five diseases for which children should be immunized.

18. Why is it better to immunize children in advance than to wait until the disease has been contracted?

19. Name two types of cytokines, and tell what role they play in immunotherapy.

a. b.

20. What are monoclonal antibodies?

14.5 IMMUNITY HAS SIDE EFFECTS (P. 276)

• While immunity preserves our existence, it also is responsible for certain undesirable effects, such asallergies, autoimmune diseases, and tissue rejection.

21. Match the descriptions with the numbered terms. Then explain your choice.1 allergy2 tissue rejection3 autoimmune disease

a. foreign HLA proteins

b. the body attacks itself

c. sensitized immune system 22. The following table indicates the blood types. Fill in the third and fourth columns by using this formula: The

donor’s antigen(s) must not be of the same type letter as the recipient’s antibody (antibodies).

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Blood Type Antigen Antibody Can Receive from Can Donate to

A A Anti-B a. b.

B B Anti-A c. d.

AB A, B ______ e. f.

O None Anti-A and B g. h.

23. This diagram shows the results of typing someone’s blood. What is the blood type? ________________________

24. Draw a similar diagram showing the results if someone has AB negative blood.

25. Consider these possible combinations of mates:Rh+ mother and Rh– father Rh– mother and Rh– fatherRh+ mother and Rh+ father Rh– mother and Rh+ fatherWhich of these combinations can cause pregnancy difficulties and why?

CHAPTER TEST

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OBJECTIVE QUESTIONS

Do not refer to the text when taking this test.1. The two collecting ducts of the lymphatic system

empty intoa. systemic arteries.b. systemic veins.c. pulmonary arteries.d. pulmonary veins.

2. The structure of a lymphatic vessel is most sim-ilar to that of aa. cardiovascular artery.b. cardiovascular arteriole.c. cardiovascular vein.d. skeletal muscle fiber.

3. Lymph nodes housea. neutrophils and monocytes.b. lymphocytes and macrophages.c. granular leukocytes.d. red blood cells.

4. Lymph is ____________________ in lymphaticvessels.a. bloodb. serumc. tissue fluidd. plasma

5. All of the following are functions of macrophagesEXCEPTa. liberate a growth factor to help leukocytes.b. phagocytize bacteria.c. scavenge dead and decaying tissue.d. transport oxygen in the blood.

Use this key for questions 6–9.Key a. thymus gland b. spleen c. lymph

node d. red bone marrow

6. causes differentiation of T cells7. purifies lymph8. contains red pulp and white pulp9. formation of agranular and granular leukocytes

10. The spleena. contains stem cells from the bone marrow.b. is located along the trachea.c. produces a hormone believed to stimulate the

immune system.d. is a blood reservoir.

11. The thymusa. contains all types of stem cells from the bone

marrow.b. is located along the trachea.c. produces a hormone believed to stimulate the

immune system.d. both b and c

12. Activity of the complement system is an exam-ple of nonspecific defense bya. barriers to entry.b. phagocytic cells.c. protective proteins.d. Both a and c are correct.

13. Secretions of the oil glands is an example of non-specific defense by a(n)a. barrier to entry.b. protective protein.c. phagocytic cell.d. acidic pH.

14. Interferon is produced by cells in response to thepresence ofa. chemical irritants.b. viruses.c. bacterial infection.d. malarial parasite in blood.

15. The most active white blood cell phagocytes area. neutrophils and macrophages.b. neutrophils and eosinophils.c. lymphocytes and macrophages.d. lymphocytes and neutrophils.

16. The white blood cells that are primarily respon-sible for specific immunity area. neutrophils.b. eosinophils.c. macrophages.d. lymphocytes.

17. Which of these is not a valid contrast between Tcells and B cells?

T cells B cellsa. matures in the thymus–matures in bone mar-

rowb. antibody-mediated immunity–cell mediated

immunityc. antigen must be presented–direct recognition

by APCd. produce lymphokines–do not produce lym-

phokines18. A particular antibody can

a. attack any type antigen.b. attack only a specific type antigen.c. be produced by any B lymphocyte.d. be produced by any T lymphocyte.

19. The clonal selection theory refers to thea. presence of four different types of T lym-

phocytes in the blood.b. response of only one type B lymphocyte to a

specific antigen.c. occurrence of many types of plasma cells,

each producing many types of antigens.

20. The portions of an antibody molecule that pairup with the foreign antigens are thea. heavy chains.b. light chains.c. variable regions.d. constant regions.

21. Which of these is incorrect?a. helper T cells–orchestrate the immune re-

sponseb. cytotoxic T cells–stimulate B cells to produce

antibodiesc. memory T cells–long-lasting active immu-

nityd. suppressor T cells–shut down the immune

response22. A person receiving an injection of gamma glob-

ulin as a protection against hepatitis is an ex-ample ofa. naturally acquired active immunity.b. naturally acquired passive immunity.c. artificially acquired passive immunity.d. artificially acquired active immunity.

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23. A person vaccinated to produce immunity to theflu is an example ofa. naturally acquired active immunity.b. naturally acquired passive immunity.c. artificially acquired passive immunity.d. artificially acquired active immunity.

24. Allergies are caused bya. strong toxins in the environment.b. autoimmune diseases.c. the overproduction of IgE.d. the receipt of IgA in breast milk.

25. Which is not true of an autoimmune response?a. responsible for such diseases as multiple scle-

rosis and myasthenia gravis and perhaps typeI diabetes

b. occurs when self-antibodies attack self-tis-sues

c. interferes with the transplantation of organsbetween one person and another

d. All of these are correct.

THOUGHT QUESTIONS

Answer in complete sentences.26. How do we know that one aspect of specific immunity is the ability of the body to recognize self as opposed to nonself?

27. How is the functioning of the immune system another example of homeostasis?

Test Results: _______ number correct ÷ 27 = _________ × 100 = _______%

ANSWER KEY

STUDY EXERCISES

1. a. return of excess tissue fluid to bloodstream b. ab-sorption of fats at intestinal villi c. defense againstdisease 2. a. F b. F c. F d. F e. T f. T 3. a. F; . . . begin with lymph capillaries b. F; . . . resemblestissue fluid that has entered the lymph vessels c. F; Theright lymphatic duct serves the right arm, the right sideof the head and neck, and the right thoracic area. d. F; . . . capillaries form lymphatic vessels first, and thesemerge before entering a particular lymphatic duct4. a. S b. RBM c. T d. S e. T f. S g. RBM 5. a. 2b. 1 c. 3 d. 1 e. 2 f. 2 g. 1 h. 3 i. 2 j. 1 k. 46.

Cytotoxic T Cell B Cell

a. yes b. yes

c. yes d. no

e. yes f. yes

g. yes h. no

i. no j. yes

7. a 8. Antigens selects the B cell that will clone. 9. c10. a. remain in body ready to produce more antibodieswhen needed b. undergo apoptosis and die off11. a. antigen-bearing site b. variable region c. con-stant region d. heavy chain e. light chain f. combinewith antigens and mark them for destruction 12. a

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13. a. Identify cell as belonging to a individual b. Theyare antigenic in someone else’s body. 14. a. secretes cy-tokines that stimulate other immune cells b. destroyscells that are infected with virus c. undergo apoptosisand die 15. a. see Figure 14.9, text page 274. b. im-munological memory, memory B, memory T 16. passiveimmunity 17. tetanus, whooping cough, diphtheria, he-patitis B, measles, mumps, rubella, polio, Haemophilisinfluenza (type b) 18. It is better to prevent a disease thantry to treat it with antibiotics. Resistant strains of bacte-ria and allergies to antibiotics are two side effects, plusviruses do not respond to antibiotic therapy. 19. a. In-terleukins activate and maintain killer activity of T cells.b. Interferon causes other cells to resist a viral infection.20. Same-type antibodies produced by the same lym-phocyte. 21. a. 2 b. 3 c. 1 22. a. A, O b. A, AB c. B,O d. B, AB e. A, B, AB, O f. AB g. O h. A, B, AB, O23. B+ 24. clumping should occur for anti-A and anti-B25. Rh– mother and Rh+ father because the mother mightform antibodies to destroy red blood cells of this or a fu-ture baby who is Rh+.

CHAPTER TEST

1. b 2. c 3. b 4. c 5. d 6. a 7. c 8. b 9. d10. d 11. d 12. c 13. a 14. b 15. a 16. d17. b 18. b 19. b 20. c 21. b 22. c 23. d24. c 25. c 26. Ordinarily, antibodies and T cells at-tack only foreign antigens. If and when they attack thebody’s own cells, illness results 27. The immune sys-tem protects the body from disease, making it possible forother systems to function properly.