CHAPTER © 2011 The McGraw-Hill Companies, Inc. All rights reserved. 4 The Lymphatic and Immune Systems

CHAPTER

© 2011 The McGraw-Hill Companies, Inc. All rights reserved.

4The Lymphatic and Immune Systems


4-2

Learning Outcomes4.1 List the pathways and organs of the lymphatic

system and give their locations.

4.2 Define lymph and tell how it is circulated in the body.

4.3 Define the terms infection, pathogen, and antigen.

4.4 List and describe the nonspecific body defense mechanisms.

4.5 Explain the signs and causes of inflammation.


4-3

Learning Outcomes (cont.)

4.6 Explain what is meant by body defenses.

4.7 Define B cells and T cells and describe their locations and functions.

4.8 Explain the importance of MHC proteins.

4.9 List the different types of T cells and describe their functions.

4.10 Explain how antibodies fight infection.


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4.11 List the different types of antibodies and tell how they differ.

4.12 Define complement proteins and give their function.

4.13 Explain the difference between the primary immune response and secondary immune response.

4.14 Explain the four different types of acquired immunities.

4.15 Describe the function of a vaccine.


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4.16 Define the terms cancer and carcinogen.

4.17 Describe how cancers are diagnosed and treated.

4.18 Explain how cancers are classified.

4.19 Describe how allergies develop.

4.20 Describe the causes, signs and symptoms, and treatments of other common immune disorders.


4-6

Introduction

• Immune system – Protects the body

against• Bacteria • Viruses • Fungi • Toxins • Parasites • Cancer

• Lymphatic system– Works with immune

system to remove disease-causing agents

– Organs• Thymus• Spleen• Lymph nodes


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The Lymphatic System• Network of

connecting vessels – Collects fluid (lymph)

between cells and returns it to bloodstream

– Picks up lipids from digestive organs and transports them to bloodstream

– Functions to defend the body against pathogens


4-8

Lymphatic Pathways

• Lymphatic capillaries– Extend into interstitial spaces– Permeable, thin walls pick up fluid, now lymph– Delivers lymph to lymphatic vessels

• Lymphatic vessels – Deliver lymph to lymph nodes

• Cells in nodes can remove pathogens from lymph and start an immune response

– Leaves nodes through efferent lymphatic vessels Lymph

System


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Lymphatic Pathways (cont.)

• Lymphatic trunks– Receive lymph from efferent lymphatic vessels – Deliver it to

• Lymphatic collecting ducts– Thoracic duct

• Left side of head and neck, left arm, left side of thorax, entire abdominopelvic area, and both legs

– Right lymphatic duct • Right side of head and neck, right arm, and right

side of chestLymph System


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Tissue Fluid and Lymph

• Interstitial fluid– Fluid in spaces between cells that has leaked

from blood capillaries and has not been picked up by body cells

– High in nutrients, oxygen, and small proteins– Becomes lymph

• Pushed through lymphatic vessels by squeezing action of neighboring skeletal muscles and breathing movement


4-11

Back


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Lymph Nodes

• Small, glandular structures

• Located along paths of larger lymphatic vessels– Afferent lymphatic

vessels – Lymph to node

– Efferent lymphatic vessels – Lymph from node


4-13

Lymph Nodes (cont.)

• More lymph enters than can leave at one time

• Cells in nodes– Macrophages – digest

unwanted pathogens– Lymphocytes – start

an immune response against pathogen

• Nodes can generate some lymphocytes


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The Thymus and Spleen

• Thymus

– Soft, bi-lobed organ

– Located just above the heart in the mediastinum

– Large in children, shrinks as we age

– Functions • Same as lymph nodes

• Also produces lymphocytes

• Produces thymosin – stimulates production of lymphocytes


4-15

The Thymus and Spleen (cont.)

• Spleen

– Largest lymphatic organ

– Located in the upper left quadrant of

abdominal cavity

– Functions

• Filters blood similarly to lymph nodes

• Removes worn-out red cells

– If removed (splenectomy), liver takes over

most of its function


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Apply Your Knowledge

What are the lymphatic collecting ducts and what area do they drain?

ANSWER: The collecting ducts are: Thoracic duct, which drains the left side of the head and neck, left arm, left side of thorax, entire abdominopelvic area, and both legs; and the right lymphatic duct, which drains the right side of the head and neck, right arm, and right side of the chest.


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Defenses Against Disease• Infection

– The presence of a pathogen in or on the body

• Pathogen – A disease-causing

agent

• Innate immunity– Nonspecific defenses

to protect against pathogens

• Nonspecific defenses

– Species resistance

– Mechanical barriers

– Chemical barriers

– Phagocytosis

– Fever

– Inflammation


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Specific Defenses Against Disease

• Immunities – Protect against very

specific pathogens– Antigens

• Foreign substances in the body

– Haptens• Foreign substances too

small to start an immune response by themselves

• Other substances– Proteins – antibodies

and complements– WBCs – lymphocytes

and macrophages– Lymph system

• Cytokines – assist in immune response regulation

• Monokines – increase B cell production and stimulate WBC production


4-19

Defenses Against Disease (cont.)

Two major types of lymphocytes

B Cells and T Cells

Recognize antigens in the body

T Cells Cell-mediated response Bind to antigens on cells

and attack them directly Secrete lymphokines that increase T cell production and directly kill cells with antigens

T Cells Cell-mediated response Bind to antigens on cells

and attack them directly Secrete lymphokines that increase T cell production and directly kill cells with antigens

B cells Respond to antigens by becoming plasma cells Plasma cells make antibodies Memory B cells produce stronger response with next exposure to antigen

B cells Respond to antigens by becoming plasma cells Plasma cells make antibodies Memory B cells produce stronger response with next exposure to antigen

Diagram


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• T cell activation – Begins when macrophage ingests and digests

pathogen with antigen on it– Antigens are placed on cell membrane of

macrophage – T cell recognizes and binds to antigen and the

major histocompatibility complex (MHC) on the surface of the macrophage

– Now can divide to form other types of T cells


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• Types – Cytotoxic T cells

• Protect body against viruses and cancer cells

– Helper T cells• Increase antibody formation, memory cell

formation, B cell formation, and phagocytosis

– Memory T cells• Remember the pathogen that activated original

T cell• Later exposures trigger an immune response more

effective than initial response


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• Natural killer (NK) cells

– Type of lymphocyte

– Primarily target cancer cells

– Kill on contact

– Do not recognize a specific antigen


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Identify whether each item refers to T cells, B cells, or NK cells:

___ Primarily target cancer cells

___ Respond to antigens by becoming plasma cells

___ Must be activated to respond to an antigen

___ Bind to antigens on cells and attack them directly

___ Kill on contact

___ Need macrophages and MHC for activation

___ Make antibodies against specific antigen

B

NK

T

T

T

B

NK

ANSWER:

Right on Target!


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Antibodies

• Also called immunoglobulins– IgA

• Prevents pathogens from entering body

– IgD • Found on B cell membranes• Thought to control B cell activity

– IgE • Found with IgA• Involved in triggering allergic reactions


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Antibodies (cont.)

– IgG• Recognizes bacteria, viruses, and toxins• Activates complements

– IgM • Large and binds to antigens on food,

bacteria, or incompatible blood cells• Activates compliments


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Antibodies (cont.)

• Actions that occur when antibodies bind to antigens

– Allow phagocytes to recognize and destroy antigens

– Cause antigens to clump together, causing them to be destroyed by macrophages

– Cover the toxic portions of antigens, making them harmless

– Activate complement

• Group of proteins in serum that attack pathogens by forming holes in them

• Attract macrophages to pathogens and can stimulate inflammation


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What are the possible actions that occur when antibodies bind to antigens?

ANSWER: Possible actions include: They allow phagocytes to recognize and destroy antigens. They make antigens clump together, causing them to be destroyed by macrophages. They cover the toxic portions of antigens to make them harmless. They activate complements.

Very Good!


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Immune Responses and Acquired Immunity

• Primary immune response occurs with first exposure to antigen– Slow process– Memory cells are formed

• Secondary immune response with next exposure to same antigen– Quick and carried out by memory cells– Usually prevents person from developing disease

from the antigen


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Immune Responses and Acquired Immunity (cont.)

• Naturally acquired active immunity– Natural exposure to antigen – having an

illness– Makes antibodies and memory cells– Long-lasting

• Artificially acquired active immunity– Injected with pathogen – immunizations or

vaccines– Makes antibodies and memory cells– Long-lasting


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Immune Responses and Acquired Immunity (cont.)

• Naturally acquired passive immunity– Acquired from mother

• Breast milk• Placenta

– Short-lived

• Artificially acquired passive immunity– Injected with antibodies (such as antivenom)– Short-lived


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ANSWER: Immunization is an artificially acquired immunity because a person develops this immunity by being injected with a pathogen and then making antibodies and memory cells against the pathogen.

After you give an immunization to a 2-year-old, her mother asks you why this will work to prevent her from getting a disease.


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Major Immune System Disorders• Cancer

– Uncontrolled growth of abnormal cells form malignant tumors

– Factors known to cause cancer are called carcinogens

– Treatment based on stage0 – very early; cancer cells localizedI – spread to deeper layers or some in surrounding tissuesII – spread to surrounding tissues but contained in primary siteIII – spread beyond primary site into nearby areasIV – spread to other organsRecurrent – reappeared after treatment


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Major Immune System Disorders (cont.)

• Allergies

– Immune response to an allergen

– IgE antibodies bind to allergens and stimulate mast cells to release histamine and heparin, triggering allergic response

– Allergy shots• Small amounts of allergen stimulates production of

IgG to prevent IgE from binding to antigen • IgG antibodies do not stimulate mast cells, so

immune response is not generated


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Major Immune System Disorders (cont.)

– Allergy signs/symptoms• Inhaled allergens – runny nose, sneezing, coughing,

wheezing

• Ingested allergens – nausea, vomiting, diarrhea

• Skin allergens – rashes

• Allergens in blood – most life-threatening; can affect many organs

– Treatment• Antihistamines, decongestants – OTC or prescription

• Epinephrine for anaphylaxis – vasoconstriction, increasing BP

– Anaphylaxis – life-threatening response


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Common Immune System Disorders

• Autoimmune disease– Body attacks its own antigens– Examples

• Scleroderma• Rheumatoid arthritis• Multiple sclerosis• Glomerulonephritis• Crohn’s disease• Diabetes mellitus, type I


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Common Immune System Disorders (cont.)

Disorder Description

AIDS Development of severe signs and symptoms caused by HIV as it destroys lymphocytes; leaves immune system weakened and susceptible to other diseases

Chronic fatigue syndrome (CFS)

Condition of severe tiredness not relieved by rest and not related to other illnesses

Lymphedema Blockage of lymphatic vessels results in tissue swelling that increases over time


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Common Immune System Disorders (cont.)

Disorder Description

Mononucleosis “Mono”; highly contagious viral infection spread through saliva of infected person

Systemic lupus erythematous (SLE)

Autoimmune disorder; produces antibodies that target own cells and tissues; affects women more often than men


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Matching:

___ Immune response to a substance A. CFS

___ Blockage of lymphatic vessels B. SLE

___ “Kissing disease” C. Cancer

___ “Butterfly” rash on face D. Autoimmune disease

___ Severe tiredness E. Lymphedema

___ Uncontrolled growth of abnormal cells F. Mononucleosis

___ Body attacks its own antigens G. Allergy

G

F

E

D

C

B

A

ANSWER:


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In Summary

4.1 The lymph system is composed of pathways known as lymph vessels. In addition to the lymph vessels, the organs of the lymphatic system include lymph nodes located throughout the body, the thymus in the mediastinum, and the spleen located in the LUQ.

4.2 Lymph is the body fluid found between the body’s cells. It circulates through the body via lymphatic capillaries, lymphatic vessels, lymph nodes, lymphatic trunk, collecting ducts, and to the subclavian vein.


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In Summary (cont.)

4.3 Infection is the presence of a pathogen in or on the body. A pathogen is a disease-causing agent, and antigens are foreign substances within the body that may or may not cause disease.

4.4 The nonspecific body defenses include species resistance, mechanical and chemical barriers, phagocytosis, fever, and inflammation.

4.5 Inflammation is the result of injury or infection. Signs are redness, heat, swelling, and pain.


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In Summary (cont.)

4.6 Specific defenses are immunities or defenses against very specific antigens.

4.7 B and T cells come from the bone marrow, thymus, lymph nodes, spleen, and the lining of the digestive tract and are found circulating in the blood. B cells utilize memory and plasma cells in a process called humoral or antibody-mediated immunity, and T cells bind directly to cell antigens, attacking them directly, producing cell-mediated immunity.


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In Summary (cont.)

4.8 T cells cannot be activated to produce immunity without MHC proteins and macrophages.

4.9 Activated T cells may form cytotoxic cells which protect the body against viruses and certain types of cancer. Other T cells may become helper T cells, which increase antibody and memory cell and B cell formation and phagocytosis. Still other T cells become memory cells.

4.10 Antibodies may work in the following ways: phagocytosis, antigen clumping, covering (inactivating) toxic portions of antigens, and activating complements.


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In Summary (cont.)

4.11 Antibodies are also known as immunoglobulins. IgA prevents pathogens from entering the body; IgD controls B cell activity; IgE works with IgA in triggering allergic reactions; IgG recognizes bacteria, viruses and toxins and activates complements; and IgM binds to antigens on food, bacteria, or incompatible blood cells. IgM also activates complements.


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In Summary (cont.)

4.12 Complements are serum proteins that attack pathogens by forming holes in them. They also attract macrophages and can stimulate inflammation.

4.13 A primary immune response occurs the first time a person is exposed to an antigen. The response is slow and takes several weeks to occur. A secondary immune response occurs at the next exposure. This response is very quick and may prevent the person from becoming ill.


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In Summary (cont.)

4.14 The four types of immune response are natural active immunity, such as when someone becomes ill and develops immunity; artificial active immunity, as when an injection is given against a pathogen, preventing illness; natural passive immunity occurs when an infant has its mother’s immunity for a short while after birth and through breast-milk; and artificial passive immunity occurs after injection of antibodies such as with an antivenom.


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In Summary (cont.)

4.15 Vaccines are used to produce artificially acquired active immunity.

4.16 Cancer is defined as the uncontrolled growth of abnormal cells. A carcinogen is an agent that is known to cause cancer.

4.17 Cancer diagnoses can come about in many ways, but often a biopsy confirms the diagnosis. Treatments vary depending on the type and stage of the cancer, but treatment options include surgery, including bone marrow transplants, chemotherapy, and radiation therapy, as well as newer immune therapies.


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In Summary (cont.)

4.18 Cancers are classified as Stages IIV and recurrent. Definitions of these stages may be found in Table 4-1.

4.19 An allergic reaction is an immune response to a substance that is not normally considered harmful to the body. Allergic reactions can also be an excessive immune response. Allergens are substances that produce an allergic response.


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In Summary (cont.)

4.20 Diseases and disorders of the immune system include autoimmune diseases, where the body attacks its own antigens, as well as numerous other diseases, including some cancers, caused by pathogens, allergens, and other antigens. The signs, symptoms and treatments are as numerous and varied as the diseases. Some of the more common diseases and disorders are discussed in the Pathophysiology section at the end of this chapter.


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End of Chapter 4

Thought is an infection. In the case of certain thoughts, it becomes

an epidemic.

~Wallace Stevens

Documents

CHAPTER © 2011 The McGraw-Hill Companies, Inc. All rights reserved. 4 The Lymphatic and Immune Systems