The Lymphatic System and Body Defenses Chapter 12

Name three things involved in the formation of antibodies.

(1) an antigen activating some of the body's B cells (2) activated B cells producing many plasma cells (3) plasma cells releasing antibodies into the blood

What are the three ways that the cytokines which helper T cells release act indirectly to rid the body of antigens?

(1) stimulating cytotoxic T cells and B cells to grow and divide (2) attracting other types of protective white blood cells, such as neutrophils, into the area (3) enhancing the ability of macrophages to engulf and destroy microorganisms

What two benefits do we receive from vaccines?

(1) they spare us most of the signs and symptoms (and discomfort) of the disease that would otherwise occur during the primary response (2) the weakened antigens are still able to stimulate antibody production and promote immunological memory.

What are three important aspects of adaptive defense?

1. It is antigen specific—it recognizes and acts against particular pathogens or foreign substances. 2. It is systemic—immunity is not restricted to the initial infection site. 3. It has "memory"—it recognizes and mounts even stronger attacks on previously encountered pathogens.

Name the three important aspects of the adaptive defense system.

1. It is antigen-specific—it recognizes and acts against particular pathogens or foreign substances. 2. It is systemic—immunity is not restricted to the initial infection site. 3. It has "memory"—it recognizes and mounts even stronger attacks on previously encountered pathogens.

Once the inflammatory process has begun:

1. Neutrophils, responding to a gradient of diffusing inflammatory chemicals, enter the blood from the bone marrow and roll along the blood vessel walls, following the "scent." 2. At the point where the chemical signal is the strongest, they flatten out and squeeze through the capillary walls, a process called diapedesis. 3. Still drawn by the gradient of inflammatory chemicals (positive chemotaxis), the neutrophils gather at the site of tissue injury, and within an hour, they are busily devouring any foreign material present. 4. As the counterattack continues, monocytes follow neutrophils into the inflamed area. 5. Monocytes are fairly poor phagocytes, but within 12 hours after entering the tissues they become macrophages with insatiable appetites. 6. The macrophages continue to wage the battle, replacing the short-lived neutrophils at the site of damage. Macrophages are the central actors in the final disposal of cell debris as the inflammation subsides.

How does the inflammatory process work?

1. When cells are damaged, they release inflammatory chemicals, including histamine and kinins 2. The inflammatory chemicals cause blood vessels in the area to dilate, make capillaries leaky, and attract phagocytes and white blood cells to the area (called positive chemotaxis) 3. Dilation of the blood vessels increases the blood flow to the area, accounting for the redness and heat observed 4. Increased permeability of the capillaries allows fluid to leak from the blood into the tissue spaces, causing local edema (swelling) that also activates pain receptors in the area as pressure in the tissues builds.

What two semi-independent parts does the lymphatic system consist of?

A meandering network of lymphatic vessels and various lymphoid tissues and organs scattered throughout the body.

What is the principal problem common to all immunodeficiency diseases?

Abnormal production or functioning of immune cells or complement.

What is an event that represents the body's third line of defense?

Adaptive response mediated by lymphocytes

Distinguish among precipitation, agglutination, and opsonization.

Agglutination cross-links cell-bound antigen; precipitation cross-links soluble antigen, which then falls out of solution like clotting proteins that have been activated; opsonization is the "marking" of antigen for phagocytosis, which also makes it a bit sticky so it is easier for phagocytes to "catch."

Which antibody capability causes a transfusion reaction with A or B erythrocyte antigens?

Aggultination

Sheila is receiving a kidney transplant. The donor is her fraternal twin. What name is given to this type of graft?

Allograft.

What is the difference between an antigen and a self-antigen?

An antigen is a foreign substance in the body. A self-antigen is a body protein, typically displayed in the plasma membrane, that is foreign to anyone but oneself.

What is an allergy?

An overzealous immune response against an otherwise harmless substance that causes injury to the body.

_________________ are made in response to an infection.

Antibodies

What are monoclonal antibodies?

Antibodies produced from a single group of genetically identical B-cells

___________________ are found on pathogens.

Antigens

What are the four major types of transplants, or grafts?

Autografts, Isografts, Allografts, Xenografts

______________are part of the specific immune response.

B cell production of antibodies

What is the main difference between the two arms of the adaptive response?

B cells secrete their antibody "weapons," whereas T cells fight their antigens directly

Which lymphocytes can target specific extracellular antigens?

B lymphocytes

Which produce antibodies: the B or T lymphocytes?

B lymphocytes

What are the two types of lymphocytes involved in adaptive immune responses?

B lymphocytes and T lymphocytes

How do the functions of B lymphocytes and T lymphocytes in body protection differ?

B lymphocytes mount a humoral response by producing antibodies. T lymphocytes mount the cellular response by activating B cells and cytotoxic T cells and stimulating the inflammatory response.

Describe how fever helps protect the body.

Bacteria require large amounts of iron and zinc to multiply, but during a fever the liver and spleen gather up these nutrients, making them less available. Fever also increases the metabolic rate of tissue cells in general, speeding up repair processes.

How can antibodies bind to more than one antigen at a time?

Because antibodies have more than one antigen-binding site

What is the benefit of having fewer efferent than afferent lymphatic vessels?

Because the outlet is smaller than the inlet to the lymph node, the lymph fluid stops flowing briefly in the lymph node, giving macrophages and lymphocytes time to monitor the lymph for pathogens and process them.

Why is the flow of lymph through the node very slow, kind of like sand flowing through an hourglass?

Because there are fewer efferent vessels draining the node than afferent vessels feeding it

What immunity occurs when lymphocytes defend the body?

Cellular immunity (cell-mediated immunity)

What is the chief antibody ammunition used against cellular antigens, such as bacteria or mismatched red blood cells?

Complement

Complement and agglutination aid phagocytosis, but they assist it in different ways. What is this difference?

Complement fixation opsonizes, or provides "knobs" for the phagocyte to attach to, whereas agglutination binds antigens (typically microorganisms) together into large complexes that become nonmobile and easier to destroy.

lymph capillaries

Contain endothelial cells separated by flaplike valves that can open wide

This outer part of the lymph node contains collections of lymphocytes (follicles).

Cortex

___________________________________ specialize in killing virus-infected, cancer, or foreign graft cells.

Cytotoxic (killer T cells) cells

What cells specialize in killing virus-infected, cancer, or foreign graft cells directly?

Cytotoxic T cells

What releases the toxic chemicals called perforin?

Cytotoxic T cells

Which are among the most common indicators of inflammation?

Edema and pain

What would be the consequence of blockage of the thoracic duct?

Edema in the areas that drain into the thoracic duct.

Explain how phagocytes engulf foreign particles by the process of phagocytosis.

Flowing cytoplasmic extensions bind to the particle and then pull it inside, forming a phagocytic vesicle. The vesicle then fuses with a lysosome, where enzymes digest its contents.

What are germinal centers?

Germinal centers are specialized B cell environment in lymph node. Where proliferation, somatic hypermutation, and selection of antigen binding occurs.

What autoimmune disease causes the thyroid gland produces excessive amounts of thyroxine?

Graves' disease

Where exactly doe sand antigen bind to an antibody molecule?

Heavy-chain variable region and light-chain variable region

What cells release a variety of cytokines that act indirectly to rid the body of antigens by (1) stimulating cytotoxic T cells and B cells to grow and divide; (2) attracting other types of protective white blood cells, such as neutrophils, into the area; and (3) enhancing the ability of macrophages to engulf and destroy microorganisms?

Helper T cells

Which are the T cells that act as the "directors" or "managers" of the adaptive immune response. Once activated, they circulate through the body, recruiting other cells to fight the invaders?

Helper T cells

In which branch of the adaptive response do helper T cells participate?

Helper T cells "direct" both humoral and cell-mediated adaptive responses; they interact with both B cells and T cells to stimulate cell division; release cytokines to recruit other phagocytes, such as neutrophils; and enhance macrophage activity.

What type of immunity is provided by antibodies (immune proteins) that are present in the body's fluids?

Humoral immunity (antibody-mediated immunity)

Which antibody is found mainly in secretions that bathe body surfaces, such as mucus and tears and plays a major role in preventing pathogens from gaining entry into the body?

IgA

Which class of antibody is found in saliva and tears?

IgA, a dimer.

Which antibody is the most abundant antibody in blood plasma?

IgG

Which antibody is the only type that can cross the placental barrier?

IgG

Which antibody class is usually arranged as a pentamer?

IgM

Which are the only antibodies that can fix complement?

IgM and IgG

What are the five antibody classes?

IgM, IgA, IgD, IgG, IgE

What causes the difficulty in breathing that occurs with anaphylactic shock?

In anaphylactic shock, released histamine causes constriction of the bronchioles, sudden vasodilation, and fluid loss.

Where does the "programming" phase leading to immunocompetence occur for T cells?

In the thymus.

What is a hapten?

Incomplete antigens that can induce antibodies (ie penicllin, poison ivy)

What are macrophages?

Infection-fighting organisms in lymph

How do the innate and adaptive defenses differ?

Innate defenses are nonspecific and always ready to protect the body. They include intact membranes (mucosa, skin), inflammatory response, and several protective cell types and chemicals. Adaptive defenses must be programmed and specifically target particular pathogens or antigens.

_______________ is made by dying cells in response to virus attacks.

Interferon

How does complement cause lysis of a pathogenic microorganism?

It attaches to foreign cells, and when it is activated, membrane attack complexes (MACs) are inserted in the foreign cell's membrane and produce lesions that allow water entry and cause lysis.

What does the spleen do?

It filters and cleanses blood of bacteria, viruses, and other debris. It provides a site for lymphocyte proliferation and immune surveillance. It also destroys worn-out red blood cells and returns some of their breakdown products to the liver. Plus, it stores platelets and acts as a blood reservoir (like the liver)

What are two things to remember about active immunity?

It is naturally acquired during bacterial and viral infections, during which we may develop the signs and symptoms of the disease and suffer a little (or a lot), and it's artificially acquired when we receive vaccines.

__________________________ are collections of lymphocytes

Lymph node follicles

____________________ filter lymph, an internal body fluid.

Lymph nodes

How do lymphatic capillaries and blood capillaries differ structurally from each other?

Lymphatic capillaries are blind-ended and not fed by arteries as blood capillaries are. They also have flaplike minivalves that make them more permeable than blood capillaries.

_______________________ is an enzyme that destroys bacteria.

Lysozyme

What are the central actors in the final disposal of cell debris as the inflammation subsides?

Macrophages

In which lymph node structure are phagocytic macrophages found?

Medulla

______________ promote cell lysis by direct cellular attack against virus-infected or cancerous body cells.

NK cells

What occurs when antibodies bind to specific sites (usually at or close to the site where a cell would bind) on bacterial exotoxins or on viruses that can cause cell injury, blocking the harmful effects of the exotoxin or virus by preventing them from binding to body cells?

Neutralization

Regarding the action of antibodies, what is neutralization?

Neutralization occurs when antibodies attach to viruses or bacterial toxins, thereby blocking the virus or toxin from injuring the body.

Lymphatic capillaries are so remarkably permeable that they were once thought to be open at one end like a straw. Are they?

No. Instead, the edges of the endothelial cells forming their walls loosely overlap one another, forming flaplike mini-valves that act as one-way swinging doors They gape open when the fluid pressure is higher in the interstitial space, allowing fluid to enter the lymphatic capillary. However, when the pressure is higher inside the lymphatic vessels, the endothelial cell flaps are forced together, preventing the lymph from leaking back out and forcing it along the vessel.

In which three regions of the body are the lymph nodes most densely located?

Particularly large collections of lymph nodes occur in the axillary, inguinal, and cervical regions.

_________________ initiate disintegration of the target cell membrane and nucleus.

Perforins

Found in the wall of the small intestine, _______ capture(s) and destroy(s) bacteria before they invade the intestinal wall.

Peyer's patches

Found in the wall of the small intestine, __________ capture(s) and destroy(s) bacteria before they invade the intestinal wall.

Peyer's patches

What resemble tonsils and are found in the wall of the distal small intestine?

Peyer's patches

What collection of small lymphoid tissues is referred to as mucosa-associated lymphoid tissue (MALT)?

Peyer's patches, the appendix, and the tonsils

What is a form of natural passive immunity, in which no immunological memory is established?

Placenta or breast milk

What are the major antibody-producing cells?

Plasma cells

Suzy had the flu last winter and got it again this year. However, her doctor says this year's flu is a new strain. Is Suzy's body mounting a primary or a secondary immune response?

Primary response—this year's new strain will be seen by the body as a different virus.

How do the lymph nodes help protect the body?

Producing lymphocytes

What are the four common indicators of inflammation?

Redness, heat, swelling (edema), and pain.

What autoimmune disease which systematically destroys joints?

Rheumatoid arthritis (RA)

Which areas are drained by the right lymphatic duct?

Right arm and the right side of the head

Which areas are drained by the thoracic duct?

Right leg and the left arm

_________________ are naturally existing antigens, which the body does not recognize as foreign or harmful.

Self-antigens

What are two possible causes of autoimmune disease?

Self-proteins that were not previously exposed to the immune system appear in the circulation, or foreign antigens that resemble self-antigens arouse antibodies that attack the self-antigens.

What traps many microorganisms that enter digestive and respiratory passageways?

Sticky mucus

T cells must take part in what is sometimes called the "double handshake" in order to be activated. What does this mean?

T cells have to bind to both an antigenic particle and to a self-protein on the antigen-presenting cell.

Which lymphocytes can recognize and eliminate specific virus-infected or tumor cells?

T lymphocytes

How is the lethal hit accomplished?

The cytotoxic T cell inserts perforin (toxic chemicals) into the foreign antigen's plasma membrane, which then develops holes. Then granzymes, enzymes from the T cell's cytoplasmic granules, enter and kill the foreign cell.

Describe how the cells that form the walls of lymph capillaries aid in regulating interstitial fluid.

The edges overlap, making a mini valve.

Where and how does lymph enter the lymph node?

The enter through the convex side of a lymph node through afferent lymphatic vessels.

What nonspecific response is triggered whenever body tissues are injured?

The inflammatory response

How is the adaptive system different from the innate defenses?

The innate defenses are always prepared to defend the body, but the adaptive system must be sensitized by an initial exposure to a foreign substance (antigen) before it can protect the body against the invader. It also remembers what invaders it has fought

What is MALT?

The lymphoid tissue associated with the mucosa—tonsils in the throat, and Peyer's patches in the intestinal walls—which acts to prevent pathogens from entering the body through the mucosa.

What anatomical characteristic ensures that lymph flows through the lymph nodes slowly?

The number of afferent lymphatic vessels entering the node is greater than the number of efferent vessels leaving the node at the hilum. Therefore, lymph flow stagnates somewhat.

Which lymphoid organ gets rid of aged red blood cells?

The spleen destroys worn-out RBCs.

What are the first lymphoid organs to appear in the embryo?

The thymus and the spleen

What is the essential role of macrophages and dendritic cells in adaptive immunity?

They are antigen presenters to the T cells.

How do natural killer (NK) cells work?

They attack the target cell's membrane and release lytic chemicals called perforin and granzymes (enzymes), which degrade target cell contents. Shortly thereafter, the target cell dies as its membrane and nucleus disintegrate.

What is the importance of the variable region of antibodies?

This is the region that binds to the antigen.

What is the purpose of interferons?

To diffuse to nearby cells and bind to their membrane receptors. This binding stimulates the synthesis of proteins that "interfere" with the ability of viruses to multiply within these still-healthy cells, reducing the spread of the virus.

Why are the respiratory tract mucosa ciliated?

To prevent dust- and bacteria-laden mucus from entering the lungs

What is the function of the thymus?

To produce hormones, thymosin and others, that function in the programming of T lymphocytes so they can carry out their protective roles in the body

What is the main job of the body's third line of defense?

To recognize foreign molecules (antigens) and either inactivate or destroy them

What is the role of regulatory T cells in the adaptive immune response?

To slow or stop the immune response once the "enemy" has been conquered.

__________ trap pathogens entering the throat.

Tonsils

What is a form of artificially acquired immunity, which typically results in the production of memory cells?

Vaccine

Which type of infectious microorganism causes the body's level of interferons to rise?

Viruses elicit interferon formation.

Proteins, and even larger particles such as cell debris, bacteria, and viruses, are normally prevented from entering blood capillaries, but they enter the lymphatic capillaries easily, particularly in inflamed areas, and then use the lymphatic system to travel throughout the body. How is this dilemma resolved?

White blood cells (WBCs) can also travel in lymph and lymph takes "detours" through the lymph nodes, where it is cleansed of debris and "examined" by cells of the immune system.

What surrounds each lymph node?

a fibrous capsule

What does the term complement refer to?

a group of at least 20 plasma proteins that circulate in the blood in an inactive state, much like inactive clotting proteins

What is the thymus?

a lymphoid mass found in the anterior mediastinum overlying the heart.

Give two examples of a phagocyte

a macrophage or neutrophil

What is pus?

a mixture of dead or dying neutrophils, broken-down tissue cells, and living and dead pathogens

What does mucosa-associated lymphoid tissue (MALT) collectively act as?

a sentinel to protect the upper respiratory and digestive tracts from the constant attacks of foreign matter entering those cavities.

What is Glomerulonephritis?

a severe impairment of kidney function due to acute inflammation

What is systemic lupus erythematosus (SLE)?

a systemic disease that occurs mainly in young women and particularly affects the kidneys, heart, lungs, and skin

What are natural killer (NK) cells?

a unique group of aggressive lymphocytes that can lyse (burst) and kill cancer cells, virus-infected body cells, and some other nonspecific targets well before the adaptive arm of the immune system is enlisted in the fight

The thymus gland is part of the _______________ defense system.

adaptive

The most common overreactions of the immune system are known as _______.

allergies

What are the most important disorders of the immune system?

allergies, autoimmune diseases, and immunodeficiencies.

Which tissue grafts are taken from a person other than an identical twin (such as a deceased person) ?

allografts

What is rheumatoid arthritis (RA)?

an autoimmune disease autoimmune disease which systematically destroys joints

What is Graves' disease?

an autoimmune disease in which the thyroid gland produces excessive amounts of thyroxine

What is type 1 diabetes mellitus?

an autoimmune disease which destroys pancreatic beta cells, resulting in deficient production of insulin

What is multiple sclerosis (MS)?

an autoimmune disease which destroys the white matter (myelin sheaths) of the brain and spinal cord

What is myasthenia gravis?

an autoimmune disease which impairs communication between nerves and skeletal muscles

B lymphoctyes and plasma cells secrete ____________________.

antibodies

Proteins secreted by plasma cells that bind to specific pathogens are called _______

antibodies

Antibodies bind to _________________

antigens

Macrophages and dendritic cells present ______________.

antigens

These are medications administered to counteract the effects of histamine.

antihistamines

Give the definition of an antigen

any substance capable of mobilizing the immune system and provoking an immune response

What is an antigen?

any substance capable of provoking an immune response

The ___________________ catches and destroys bacteria going into the large intestines.

appendix

The immune cells involved in allergic reactions, especially in the lining of the nasal passages, causing sneezing and runny noses _______.

are mast cells

Is passive immunity naturally or artificially conferred when a person receives immune serum or gamma globulin (donated antibodies).

artificially

This is a condition that prevents normal ventilation.

asthma

Where and how does lymph exit the lymph node?

at its indented region, the hilum, through efferent lymphatic vessels.

Which tissue grafts are transplanted from one site to another in the same person?

autografts

Why do organ transplants have mixed success?

because the immune system is ever vigilant, and rejection is a real problem

Why is it important for the respiratory tract to keep bacteria out of the lungs?

because the warm, moist environment of the lungs provides ideal conditions for bacterial growth

Why are igM antibodies called pentameters?

because they are constructed of five linked monomeres

During an inflammatory response, histamine is released _______ blood vessels dilate and pain receptors are activated.

before

Where do natural killer (NK) cells roam?

blood and lymph

Which do macrophages play an important role in, innate or adaptive mechanisms?

both

How do lymphatic vessels form?

by budding off veins

How does the immune system protect us directly?

by cell attack

What are some ways that antibodies inactivate antigens?

by complement fixation, neutralization, agglutination, opsonization, and precipitation

How do innate mechanisms reduce the workload of the adaptive defense mechanisms?

by generally preventing the entry and spread of microorganisms throughout the body.

How does the immune system protect us indirectly?

by releasing mobilizing chemicals and protective antibody molecules

How do cells in lymph nodes in particular help protect the body?

by removing foreign material such as bacteria and tumor cells from the lymphatic stream and by producing lymphocytes that function in the immune response

Although the virus-infected cells can do little to save themselves, how can they help defend cells that have not yet been infected?

by secreting small proteins called interferons, which diffuse to nearby cells and bind to their membrane receptors. This binding stimulates the synthesis of proteins that "interfere" with the ability of viruses to multiply within these still-healthy cells, reducing the spread of the virus.

How do viruses harm the body?

by taking over target cells (different cells for different viruses), then using cellular machinery and nutrients to reproduce themselves

Without the lymphatic system, our ________________ system would stop working, and our ____________ system would be hopelessly impaired

cardiovascular; immune

Complement proteins must be activated in a particular sequence called a _________________, which insures that complement is not accidentally activated.

cascade

What does the outer part of the lymph node (its cortex) contain?

collections of lymphocytes called follicles, many of which have dark-staining centers called germinal centers.

Antibodies fix ____________________

complement

The production of a MAC, to create holes in the cell surface of pathogens, is the action of __________.

complement

__________________________, a group of plasma proteins that lyse microorganisms and intensify the inflammatory response, is an element of the second line of defense.

complement

What are the two most important antimicrobial proteins that enhance the innate defense?

complement and interferon

What occurs when complement proteins bind to certain sugars or proteins (such as antibodies) on the foreign cell's surface?

complement fixation

Which two ways that antibodies inactivate antigens are most important to body protection?

complement fixation and neutralization

What are lymph nodes buried in?

connective tissue

What are trabeculae?

connective tissue strands that extends inward to divide the lymph node into a number of compartments

What do both the spleen and the liver do during hemorrhage?

contract and empty their blood into circulation to help bring the blood volume back to its normal level

What are clones?

decedents of a single cell

What are the major types of cells acting as APCs?

dendritic cells, macrophages, and B lymphocytes

The most important function of the spleen is to _______.

destroy and process worn-out red blood cells

During an inflammatory response, histamine is released. This causes blood vessels to __________ and pain receptors to be activated.

dilate

When does the thymus function at peak level?

during youth

What connects to the lymph node at the hilum?

efferent lymphatic vessels

There are fewer ______________ vessels draining the lymph node than ____________ vessels feeding it

efferent; afferent

How do antimicrobial proteins enhance the innate defense?

either by attacking microorganisms directly or by hindering their ability to reproduce

What does a phagocyte do?

engulfs a foreign particle by the process of phagocytosis

The keratinized _______ and _______ are the body's first line of defense against pathogens.

epidermis, mucous membranes

The keratinized __________ and the __________ are the body's first line of defense against pathogens.

epidermis; mucous membranes

Why are high fevers dangerous?

excess heat "scrambles" (destroys protein structure) enzymes and other body proteins, rendering them nonfunctional

What does pyrogen induce?

fever

What are interferons unable to assist with?

fighting bacterial or fungal infections.

What do the lymphatic vessels transport?

fluids that have escaped from the blood back to the cardiovascular system

What is the basic structure of all antibodies?

four polypeptide chains linked together by disulfide bonds

Which is the best way to classify the immune system in an anatomical sense: functional system or organ system?

functional system

The dark-staining _________________ of lymph node follicles enlarge when B cells are generating plasma cells, which release antibodies.

germinal centers

Which parts of the lymph node show increased activity when antibody production is high?

germinal centers

Three important aspects of the adaptive defense are that it is antigen specific, it is systemic, and it _______.

has a memory

Important in recruiting other cells to fight invaders, _______ can be thought of as the "directors" or "managers" of the immune system.

helper T cells

Important in recruiting other cells to fight invaders, __________ can be thought of as the "directors" or "managers" of the immune system.

helper T cells

The main cellular target of the HIV virus that causes AIDS is

helper T cells

What do lymphocytes originate from?

hemocytoblasts in red bone marrow

The ________________ is the indented region of the lymph node from which efferent lymphatics exist.

hilum

Chemical mediators of inflammation include

histamine

Allergic symptoms, such as sneezing, runny nose, and watery eyes, result from _______.

histamines

These are chemicals released to produce inflammation.

histamines

The________________________________ pressures operating at capillary beds force fluid out of the blood at the ___________ ends of the beds ("upstream") and cause most of the expelled fluid to be reabsorbed at the ________ ends ("downstream")

hydrostatic and osmotic, arterial, venous

In addition to returning tissue fluid to circulation, what does the lymphatic system play a major role in?

immunity

What are antibodies also called?

immunoglobulins

Where are dendritic cells present?

in connective tissues and in the epidermis

Where are phagocytic macrophages located?

in the central medulla of the lymph node.

Where are large clusters of lymph nodes typically found?

in the inguinal, axillary, and cervical regions of the body

Where are the lymphoid follicles located?

in the wall of the appendix as a tube-like offshoot of the proximal large intestine.

Against what will interferon do some good?

infection of the body cells by a virus and circulating free viruses

What do lymph nodes help rid the body of?

infectious agents and cancer cells

What two mechanisms make up the immune system?

innate and adaptive defense mechanisms

What two types of mechanisms defend the body against the thousands of hostile microbes that swarm on our skin and invades our inner passageways every second of the day?

innate and adaptive defense mechanisms

The substance produced by virus-infected cells that helps other cells resist viral infection is _______.

interferon

This is a protein secreted by virus-infected cells to protect healthy neighboring cells.

interferon

The edges of the endothelial cells forming the lymphatic capillary walls loosely overlap one another, forming flaplike mini-valves that act as one-way swinging doors They gape open when the fluid pressure is higher in the __________________________, allowing fluid to enter the lymphatic capillary. However, when the pressure is higher inside the ________________, the endothelial cell flaps are forced together, preventing the lymph from leaking back out and forcing it along the vessel.

interstitial space; lymphatic vessels

What are medullary cords?

inward extensions of cortical tissue that contain both B and T cells

The inflammatory response _______.

is the body's second line of defense, after the skin

Which tissue grafts are donated by a genetically identical person, the only example being an identical twin?

isografts

What happens when complement proteins become attached to foreign cells such as bacteria, fungi, or mismatched red blood cells?

it is activated and becomes a major factor in the fight against foreign cells

Why is the spleen important in the fetus?

it is an important hematopoietic (blood cell-forming) site,

The lymphatic system is a

low-pressure, pumpless system

An infection may spread throughout the body, commonly causing swelling and tenderness of the _______.

lymph nodes

The lymphatic vessels, also called ___________________, form a one-way system, and lymph flows only ______________________.

lymphatics; toward the heart

The lymph nodes help protect the body by removing potentially threatening substances such as viruses, and by producing _______.

lymphocytes

What are the crucial cells of the adaptive system?

lymphocytes and antigen-presenting cells (APCs)

What are the most important immune cells?

lymphocytes, dendritic cells, and macrophages.

The role of NK cells is to __________.

lyse and kill nonspecific targets

What within the lymph nodes engulf and destroy bacteria, viruses, and other foreign substances in the lymph before it is returned to the blood?

macrophages

After an initial chicken pox infection/exposure, _______ would remain in the body, enabling it to respond quickly and efficiently to subsequent exposures to the same antigen.

memory T and B cells

What do cells that do not differentiate into plasma cells become?

memory cells, which are primed to respond to subsequent exposures to the same antigen

What is the third antigen capture and delivery system?

migration of dendritic cells to secondary lymphoid organs

What autoimmune disease destroys the white matter (myelin sheaths) of the brain and spinal cord?

multiple sclerosis (MS?

Which autoimmune disease impairs communication between nerves and skeletal muscles?

myasthenia gravis

What is the difference in function between the spleen of a fetus and the spleen of an adult?

n the fetus, the spleen is an important hematopoietic (blood cell-forming) site, but as a rule the adult spleen produces only lymphocytes.

What cells can act spontaneously against any such target by recognizing certain sugars on the "intruder's" surface as well as its lack of certain "self" cell surface molecules?

natural killer (NK) cells

What unique group of aggressive lymphocytes can lyse (burst) and kill cancer cells, virus-infected body cells, and some other nonspecific targets well before the adaptive arm of the immune system is enlisted in the fight?

natural killer (NK) cells

Does the body naturally or artificially produce the cell-mediated response?

naturally

Is passive immunity conferred naturally or artificially on a fetus when the mother's antibodies cross the placenta and enter the fetal circulation,

naturally

Name three parts of the nonspecific immune responses

neutrophils, acid barriers in the stomach, and inflammation

What, besides macrophages, are strategically located in the lymph nodes and respond to foreign substances in the lymphatic stream?

ollections of lymphocytes (a type of white blood cell)

For people suffering with end-stage heart or kidney disease, what are desirable treatment options?

organ transplants

What determines what foreign substances our immune system will be able to recognize and resist?

our genes, not the antigens

Natural killer cells attack the target cell's membrane, releasing _______, which initiate disintegration of the target cell membrane and nucleus.

perforins

The role of T cells is to _______.

perform a surveillance role

White blood cells that engulf and destroy bacteria are called _______.

phagocytes

White blood cells that engulf and destroy bacteria are called __________.

phagocytes

Natural killer (NK) cells are not

phagocytic

What do the lymphoid tissues and organs house?

phagocytic cells and lymphocytes, which play essential roles in body defense and resistance to disease.

The inflammatory response is independent of ___________________, though it attracts phagocytes to the affected area when the injured cells release inflammatory chemicals.

phagocytosis

What do antigen presenting cells (APCs) do?

play an essential role in activating the lymphocytes that respond to specific antigens

Besides enzymes, what do natural killer (NK) cells release?

powerful inflammatory chemicals

What is the initial response of the humoral arm of the immune system to an antigen?

primary humoral response

__________________ occurs with the first exposure to an antigen, in which antibody production is slow.

primary immune response

Antibody production is ____________ upon a second exposure.

rapid

What are the four most common indicators, or cardinal signs, of acute inflammation?

redness, heat, pain, and swelling (edema)

The ____________________________ release chemicals that suppress the activity of both T and B cells.

regulatory T cells

What cells are vital for winding down and stopping the immune response after an antigen has been successfully inactivated or destroyed.

regulatory T cells

What cells release chemicals that suppress the activity of both T and B cells?

regulatory T cells (formerly called suppressor T cells)

Natural killer cells attack the target cell's membrane by __________, which initiate disintegration of the target cell membrane and nucleus.

releasing perforins

What secretions contain lysozyme, an enzyme that destroys bacteria?

saliva and tears

A person who has recovered from mumps is protected from contracting the disease again by a _______.

secondary immune response

The most devastating congenital condition in which there is a marked deficit of both B and T cells?

severe combined immunodeficiency disease (SCID)

What are antibodies?

soluble proteins secreted by activated B cells or by their plasma-cell offspring in response to an antigen, and they are capable of binding specifically with that antigen

What is another name for the adaptive defense system?

specific defense system

The _____________ filters and cleans blood (just as lymph nodes filter lymph).

spleen

What secretes gastric juice containing hydrochloric acid and protein-digesting enzymes that both kill pathogens?

stomach mucosa

Which lymphocytes produce antibodies and oversee humoral immunity?

the B lymphocytes, or B cells

Until recently, scientists thought that the CNS had no lymphatics. Why is this not true?

the CNS is drained by lymphatics near the venous dural sinuses

Which lymphocytes constitute the cell-mediated arm of the adaptive defenses?

the T lymphocytes, or T cells

Which immune defense system fights invaders that get past the innate defenses by mounting an attack against one or more particular foreign substances?

the adaptive defense system (specific defense system)

What is referred to as the body's third line of defense?

the adaptive, or specific, defense mechanism

What is one result of complement fixation?

the formation of membrane attack complexes (MAC) that produce holes, or pores, in the foreign cell's surface. These pores allow water to rush into the cell, causing it to burst, or lyse.

What are memory cells responsible for?

the immunological memory mentioned earlier

Activated complement also amplifies what?

the inflammatory response

What kind of immune defense is our mucus membranes classified as?

the innate defense system (nonspecific defense system)

What kind of immune defense is our skin classified as?

the innate defense system (nonspecific defense system)

What kind of immune defense is the inflammatory response classified as?

the innate defense system (nonspecific defense system)

Which immune defense system responds immediately to protect the body from all foreign substances, whatever they are.

the innate defense system (nonspecific defense system)

What happens in the process of clonal selection?

the lymphocyte begins to grow and then multiplies rapidly to form an army of cells exactly like itself and bearing the same antigen-specific receptors.

What happens when large numbers of bacteria or viruses are trapped in the nodes?

the nodes become inflamed, swollen, and tender to the touch

What is another name for the innate defense system?

the nonspecific defense system

What is essential for the activation and clonal selection of T cells?

the process of antigen presentation

What do lymphocytes arise from?

the red bone marrow

What drains lymph from the right arm and the right side of the head and thorax?

the right lymphatic duct

What is passive immunity?

the short-term immunity that results from the introduction of antibodies from another person or animal.

The body's first line of defense against the invasion of pathogens is _______.

the skin

The most important nonspecific defense of the body is/are _______.

the skin

What soft organ is located in the left side of the abdominal cavity, just beneath the diaphragm, and curls around the anterolateral aspect of the stomach?

the spleen

What are some lymphoid organs besides the lymph nodes?

the spleen, thymus, tonsils, Peyer's patches, and the appendix, as well as bits of lymphoid tissue scattered in epithelial and connective tissues.

Where do both the right lymphatic duct and the large thoracic duct empty the lymph into?

the subclavian vein on their own side of the body

As lymph is transported toward the heart, what is it filtered through?

the thousands of lymph nodes that cluster along the lymphatic vessels

T cells arise from lymphocytes that migrate where?

the thymus

Lymph is transported from the lymph capillaries through successively larger lymphatic vessels, referred to as lymphatic collecting vessels, until it is finally returned to where?

the venous system through two large ducts in the thoracic region

What happens to pathogens that make it through the mechanical barriers?

they are confronted by phagocytes in nearly every body organ.

How are lymphatic vessels similar to veins?

they are thin walled, and the larger ones have valves

Why do skin secretions, urine, sebum, and the vaginal secretions of adult females inhibit bacterial growth?

they are very acidic

Where are macrophages present?

throughout the lymphoid organs and connective tissues, where they act as phagocytes in the innate defense system. Macrophages tend to remain fixed in the lymphoid organs (as if waiting for antigens to come to them).

What lymphoid mass is found in the anterior mediastinum overlying the heart?

thymus

What does the slow flow of lymph through the node allow?

time for the lymphocytes and macrophages to perform their protective functions.

What are isografts?

tissue grafts donated by a genetically identical person, the only example being an identical twin.

What are xenografts?

tissue grafts harvested from a different animal species, such as a porcine (pig) heart valve transplanted into a human.

What are allografts?

tissue grafts taken from a person other than an identical twin.

What are autografts?

tissue grafts transplanted from one site to another in the same person

What is the function of lymphatic vessels?

to pick up fluid and proteins leaked from the blood into the interstitial space.

What are the flaplike mini-valves that form the edges of the endothelial cells that form the walls of the lymphatic capillaries anchored do and what are they anchored by?

to the surrounding structures by fine collagen fibers

What is the function of tonsils?

to trap and remove bacteria or other foreign pathogens entering the throat

What small masses of lymphoid tissue are found deep to the mucosa surrounding the pharynx (throat)?

tonsils

What autoimmune disease destroys pancreatic beta cells, resulting in deficient production of insulin

type 1 diabetes mellitus

What are viruses?

unique, acellular particles—essentially nucleic acids surrounded by a protein coat—that lack the cellular machinery required to generate ATP or make proteins

The injection of weakened pathogens to produce immunity is a(n) _______.

vaccination

Developmentally, embryonic lymphatic vessels are most closely associated with the ________________

veins

How does complement fixation occur?

when complement proteins bind to certain sugars or proteins (such as antibodies) on the foreign cell's surface

What is opsonization?

when molecules released during the activation process cause the cell membranes of the foreign cells to become sticky so they are easier to phagocytize

When does anaphylactic shock occur?

when the allergen directly enters the blood and circulates rapidly through the body, as might happen with certain bee stings, spider bites, or an injection of a foreign substance (such as horse serum, penicillin, or other drugs that act as haptens) into susceptible individuals.

What causes lymph nodes to persist in swelling or enlarge over time, instead of just swell temporarily as when fighting an infection?

when they contain cancer cells

Which tissue grafts are harvested from a different animal species, such as a porcine (pig) heart valve transplanted into a human.

xenografts