Biology - Chapter 24 (The Body's Defenses)

Adaptive Immunity

1. Continually develops over your lifetime as it encounters and attacks specific pathogens. 2. The third line of defense in the immune system. 3. Consists of two types of lymphocytes, B cells and T cells.

Innate Immunity

1. Does not change from the time you were born. 2. Its components attack pathogens. 3. Includes both internal and external lines of defense, (first and second lines of defense).

As HIV depletes the body of helper T cells, the adaptive immune defenses are severely impaired. If not treated, a final stage of HIV occurs, known as ________.

AIDS.

Protruding from the surface of B cells and T cells are ___________________ that bind to an antigen.

Antigen receptors.

What are the two main types of lymphocytes?

B cells and T cells

Pathogens

Disease causing agents, such as bacteria and viruses.

What are the three main types of effector cells and what does each do?

Effector helper T cells help stimulate B cells and cytotoxic T cells. Effector B cells secrete antibodies. Effector cytotoxic T cells destroy infected cells.

Memory cells can last decades in lymph nodes, ready to be activated by a second exposure to the antigen, If the antigen is encountered again, the primary immune response will be more rapid, of greater magnitude, and of longer duration than the primary immune response.

False, 'secondary' immune response.

An allergen enters the bloodstream, where it binds to a T cell and activates it.

False, B cell

What are the two parts of the immune system?

Innate immunity and adaptive immunity

Which come into play only after infection has occurred?

Internal innate defenses: phagocytic cells, natural killers, and defensive proteins.

As blood travels in the circulatory system fluid exits blood through ___________________________.

Small gaps between the cells of capillaries.

Third line of defense (Adaptive immunity)

Strictly internal, deploying when innate immunity defenses fail to ward off a pathogen.

Name the signs of the inflammatory response.

Swelling, redness, warmth, pain, and sometimes fever.

A _______ bearing a receptor with specificity for this antigen fragment binds to both the antigen and self protein. This three-part interaction among a self protein, an antigen fragment, and an antigen receptor is required for a ______ to function.

T cell.

Everyone has experienced inflammation at some point in their lives. What are the primary signs of inflammation?

The common signs of inflammation are redness, warmth, swelling, and pain.

How does the immune system produce enough of the right cells to fight off a major infection?

The process of clonal selection causes those few cells with receptors that are complementary to the antigens of the infectious agent to selectively multiply.

How is the secondary immune response different from the primary immune response?

The secondary immune response is quicker and stronger.

The types of lymphocytes that multiply in the lymph nodes are essential to the immune system's _______ line of defenses, the __________ immunity.

Third, Adaptive.

A mutation causes your cells to be inhibited in their release of histamine. What general effect would this likely have on the inflammatory response? Refer to the figure below.

This particular mutation would likely shut down the inflammatory response as it relies on the release of histamine to dilate blood vessels and make them "leaky."

A new genetic disorder is discovered where patients are unable to create memory cells during clonal selection. What would be the effect of this disorder on your immune response?

This would likely have the effect of preventing you from mounting a secondary immune response and would leave you susceptible to the same pathogens your whole life.

B cells fully develop and mature in the bone marrow, whereas immature T cells migrate via the blood to the _____________, a gland in the chest, where they mature and become specialized.

Thymus

Allergy symptoms do not arise until the second stage which begins when the allergen enters the body again.

True.

Antigen receptors on T cells only recognize fragments of antigens and the fragments must be displayed on the surface of body cells by specialized proteins before the T cells are activated.

True.

Antigens also include toxins secreted from bacteria, molecules from mold spores, pollen, dust, as well as molecules on cell surfaces of transplanted tissue.

True.

Beating cilia extending from cells of the respiratory tract sweep mucus, including trapped pathogens, outward until the mucus is either swallowed or expelled when you sneeze, cough, or blow your nose.

True.

Because helper T cells play a central role in adaptive immunity, the destruction of these cells leads to devastating consequences.

True.

An ________ is your immune system overreacting to a(n) ________ as if it was an antigen.

allergy, allergen.

Proteins that match specific antigens based on shape:

antibodies

Upon an injury stimulus, _____________ will release _____________, which causes capillaries to ____________.

damaged cells, histamine, dilate.

Anaphylactic shock can be counteracted with injections of the hormone ___________.

epinephrine.

Each effector cell lives only _____________, and the primary immune response subsides the effector cells die out.

four to five days.

Another type of T cell, __________, does not directly carry out attacks on pathogens but aids in stimulating both the B cells and the cytotoxic T cells in their responses. Without helper T cells, B cells and cytotoxic T cells could not initiate defenses against invaders.

helper T cell.

HIV can infect a variety of cells, but it most often attacks ___________.

helper T cells

In-home pregnancy tests, antibodies are used to detect a hormone found in the urine of pregnant women called ____________________.

human chorionic gonadotropin (HCG).

Although _____________________ drugs weaken the body's defenses against infections, they greatly reduce the risk of organ rejection.

immunosuppressant

In type 1 diabetes, the ___________________ cells of the pancreas are the targets of cytotoxic T cells.

insulin-producing

Adaptive immunity is to ___________ as innate immunity is to ____________.

lymphocytes, phagocytes

Lymphocytes that can recognize a pathogen years later:

memory cells.

Each cell has 100,000 copies of an antigen receptor that detects _________________________.

only a single type of antigen.

When an organ is transplanted from a donor into a recipient, the newly transplanted cells contain self-proteins that do not match those on the recipient's cells. Thus, the recipient's cytotoxic T cells tag the transplanted cells as foreign and kill them, ultimately resulting in _________________.

organ rejection.

Bacteria, viruses, and other microorganisms that cause disease are referred to as ______________, and it is the job of your __________ to defend yourself against them. The ______________ includes a collection of vessels, tissues, and organs that provide an environment where both components of the immune system can interact.

pathogens, immune system, lymphatic system.

List three internal innate defenses and briefly describe each one.

1. Phagocytes—white blood cells that will consume invading pathogens. 2. Natural killer (NK) cells—white blood cells that attack cancer cells and cells that have been invaded by a virus. 3. Inflammatory response—general immune response to many different injury stimuli such as a burn.

Second line defenses (internal innate defenses) include:

1. Phagocytic cells. 2. Natural killer cells. 3. Defensive proteins. 4. Inflammatory response.

First line defenses (external innate defenses) include:

1. Skin (forms a tough outer layer that most bacteria and viruses cannot penetrate). 2. Nostril hairs (filter many particles from. the oincoming air). 3. Ear wax (traps pathogens before they can travel too far down the ear canal).

The two main functions of the lymphatic system are:

1. To return tissue fluid to the circulatory system. 2. To fight infection.

List the two main functions of the lymphatic system:

1. fight infection. 2. return fluid to the circulatory system.

Histamine

A chemical that causes nearby blood vessels to dilate (widen) and leak fluid into the wounded tissue, a process called swelling.

Immune System

A collection of organs, tissues, and cells that together perform vital functions of safeguarding the body from a constant barrage of pathogens.

What is an autoimmune disease?

A disease in which cells of the immune system attack certain of the body's own cells.

What is an immunodeficiency disease?

A disease in which one or more parts of the immune system are defective, resulting in an inability to fight infections.

Lymphatic system

A network of vessels, tissues, and organs where pathogens and cells involved in innate immunity and adaptive immunity interact with each other to carry out defensive actions.

Immunodeficiency disorders:

A person lacks one or more components of the immune system. Example; AIDS.

Which part provides better protection the second time a specific pathogen is encountered?

Adaptive immunity continually "adapts" to better fight specific pathogens each time they are encountered.

What is an antigen? Name some examples.

An antigen is a molecule that elicits a response from a lymphocyte. Ex.: molecules on viruses, bacteria, dust, and pollen

Allergic reactions range from seasonal nuisances to severe responses. __________________ is an especially dangerous type of allergic reaction.

Anaphylactic shock

_____________ may act as physical barriers that prevent pathogens from entering body cells. They may also block the viral attachment proteins necessary for entering and infecting a body cell.

Antibodies

What are the functions of antibodies during the adaptive immune response?

Antibodies can block pathogens from entering a body cell and can make the capture of a pathogen by phagocytes easier.

Any molecule that elicits a response from lymphocytes is called an ____________. Most antigens are molecules on the surfaces of viruses and foreign cells, such as cells of bacteria or parasitic worms.

Antigen.

___________ mature in the bone, and T cells mature in the ____________.

B cells, thymus gland.

Why do scientists suspects that innate immunity evolved before adaptive immunity?

Because innate immunity is found in animals both with and without adaptive immunity.

Lymphocytes originate from stem cells in the ______________.

Bone marrow

After nutrients and waste exchange, most of the fluid reenters the blood and the circulatory system through _______________, but some remains in the tissue.

Capillaries.

Lymph

Carried by lymphatic cells, it is similar to the interstitial fluid surrounding body cells.

____________________ include protein molecules on pollen grains, on the feces of tiny mites that live in house dust, in animal dander, and in various foods.

Common allergens

The lymphatic system

Consists of a branching network of vessels, numerous lymph nodes (little round organs packed with white blood cells), and a few other organs such as the spleen, appendix, and tonsils.

The _____________ T cell response defends against pathogens that have entered the body cells. ______________ T cells are the only T cells that actually kill infected cells. They identify infected body cells because foreign antigen fragments are "advertised", or bound to a self protein.

Cytotoxic

Inflammation

Damaged cells release chemicals that increase blood flow to the damaged area causing the wound to turn red and warm.

Phagocytic cells

Engulf bacteria and the remains of body cells killed by bacteria or by the physical injury.

Phagocytic cells (also called phagocytes)

Engulf foreign cells or molecules and debris from dead cells by phagocytosis, or "cellular eating".

Which components of innate immunity prevent infection?

External innate defenses: skin, nostril hairs, ear wax, cilia, mucus, sweat, saliva, acid

For a pathogen to get inside your body, it must first get by your body's internal innate defenses.

False, internal->external

An allergic response occurs on the first exposure to an allergen.

False, it can occur any time after the first exposure. A person has to get sensitized to the allergen before they can have a reaction to the allergen.

If your innate defenses, like barriers and inflammation, fail to stop infection, you are left completely unguarded against disease.

False, the body has its adaptive defenses.

The skin contains oils and acids that make it welcoming to many microorganisms.

False, welcoming-> inhospitable

Unlike adaptive immunity, the innate immunity defenses, specifically the B cells and T cells, must be primed before they attack foreign molecules.

False. Adaptive immunity->Innate immunity. Innate immunity->Adaptive immunity

The central dogma of biology is as follows: DNA → RNA → Protein. How does HIV violate this dogma?

HIV is an RNA virus. Once it enters the host cell, its flow of information is as follows: RNA → DNA → RNA → Protein.

Briefly explain why it is so detrimental to your immune response to have your helper T cells destroyed. Your answer should include the effects of helper T cells on B cells and cytotoxic T cells.

Helper T cells activate other components of the immune response, such as cytotoxic T cells and B cells. Without the activation of cytotoxic T cells and B cells, the adaptive immune response would essentially be nothing.

Herceptin, a genetically engineered antibody, is used to treat certain cases of aggressive breast cancer.

Herceptin

Example of treating symptoms of an illness without addressing the underlying cause:

Ibuprofen inhibits dilation of blood vessels, which reduces swelling.

Damaged cells may release other chemical signals that travel through the bloodstream to the brain, where they stimulate a fever that may discourage bacterial growth

In response to severe tissue damage or infection

Anti-inflammatory drugs dampen the _____________ and help reduce swelling and fever.

Inflammatory response

What is the single basic difference between the adaptive defenses and innate defenses?

Innate defenses are always ready to go and are nonspecific, whereas the adaptive defenses are useful only against specific pathogens.

The fluid then enters the ____________ surrounding tissues. Nutrients and wastes are exchanged in this ____________.

Interstitial space

Refer to the figure below to solve the following questions. How many days did it take for antibody concentration to peak after initial exposure to antigen X? How many days did it take for antibody concentration to peak after exposure to antigen X the second time? How many days did it take the secondary immune response to produce the same concentration of antibodies as the primary response peaked at?

It peaked at about 17 days during the initial exposure. It took about 10 days to peak during the second exposure. It took about 4 days for the antibody concentration to reach the peak during the first exposure.

Internal innate defenses

Lie in wait, confronting pathogens that make it past external defenses.

Because the lymphatic vessels penetrate nearly every tissue

Lymph can pick up pathogens from infection sites just about anywhere in the body.

What are swollen glands?

Lymph nodes where lymphocytes are multiplying during an infection.

Describe how the lymphatic system plays a role in both the innate immune response and the adaptive immune response.

Lymph nodes will contain both phagocytes (innate) and lymphocytes (adaptive) that attack invading pathogens.

This excess fluid flows into small ____________. From the small ___________, the fluid, now called lymph, drains into larger and larger _____________. Eventually, lymph enters the circulatory system through two large _____________ that fuse with veins near the shoulders.

Lymphatic vessels

Lymph nodes are key sites where particular white blood cells called _____________ multiply during times of infection.

Lymphocytes

External innate defenses

On the frontline, preventing pathogens from getting deep inside the body.

As this fluid circulates, ____________ inside lymphatic tissues and organs engulf the invaders.

Phagocytic cells

Defensive proteins

Prevent viral reproduction within body cells, others destroy pathogens directly, and still others trigger the inflammatory response.

Natural Killers cells (NK)

Recognize virus-infected and cancerous body cells. When contact is made, NK cells release chemicals that kill the diseased cells.

__________________ leads to damage and painful inflammation of the cartilage and bones of joints.

Rheumatoid arthritis.

If viruses were hiding inside body cells, what kind of lymphocytes would recognize the infection?

T cells, fragments of the pathogen would be displayed by self proteins on body cells for T cell recognition.

Why does it take at least two exposures to an allergen to trigger allergic symptoms?

The first exposure merely sensitizes you by causing the attachment of specific antibodies to mast cells. A second exposure causes the mast cells to release chemicals that trigger the symptoms of an allergic response.

Autoimmune disorders:

The immune system attacks molecules associated with the body's own cells. Example; Multiple sclerosis (MS).

When tissues becomes damaged (from cuts, scratches, bug bites, or burns, for example)

The injured cells release chemicals that trigger various internal innate defenses.

A scientists creates a treatment for allergies that involves the alteration of mast cells with the result that the mast cells are no longer able to bind antibodies produced by B cells. How would this help a person's allergies? Refer to the figure below.

The mast cells would no longer be able to bind to the allergen due to the lack of antibodies on the surface of the mast cells. In the absence of the allergen binding, there would be no release of histamine, which would lead to allergy relief.

Drugs, vaccines, and education are areas of focus for the prevention of HIV infection. The HIV pill is taken daily to block the virus from establishing an infection. A vaccine against HIV has been challenging to develop, and one does not yet exist. Currently, the most effective HIV/AIDS prevention is education.

True.

External innate defenses also include chemical barriers in the form of antimicrobial secretions.

True.

Immunodeficiency is not always an inborn condition, it can be acquired later in life.

True.

In autoimmune diseases, the immune system actually turns against the body's own molecules.

True.

In systemic lupus erythematosus (lupus), B cells make antibodies against many sorts of self molecules, even proteins and DNA released by the normal breakdown of body cells.

True.

In the process of clonal selection, an antigen activates only a tiny number of lymphocytes with specific antigen receptors. These "selected" lymphocytes then multiply through cell division, forming a clone of lymphocytes with a specific antigen receptor.

True.

In the rare genetic disease called severe combined immunodeficiency (SCD), both B cells and T cells are absent or inactive.

True.

Organ systems that are open to the external environment (such as the respiratory system and reproductive systems) are lined with cells that secrete mucus, a sticky fluid that traps bacteria, dust, and other particles.

True.

Sweat, saliva, and tears contain enzymes that disrupt bacterial cell walls.

True.

The cells of the stomach produce acid that kills most of the bacteria we swallow before they can get past the digestive system's lining and enter the bloodstream.

True.

The excess fluid heals damaged tissue by diluting toxins in it, bringing it extra oxygen, and delivering platelets and clotting proteins to it that promote scabbing.

True.

The immune system can be confronted with a vaccine composed of an inactive or otherwise harmless version of a pathogen.

True.

the internal innate defenses depend on _________ and defensive __________.

White blood cells, proteins.

Ultimately, four polypeptides are synthesized and joined to form a single Y-shaped antibody protein that is then secreted. The tip of each "Y" forms a region, ___________________, that will recognize and bind to a specific antigen in a lock and key structure.

an antigen-binding site

Crohn's disease, chronic inflammation in the digestion tract, may be caused by ________________.

an autoimmune reaction against bacteria that normally inhabit the intestinal tract.

An allergy is _______________________________________________. Antigens that cause allergies are called ____________.

an exaggerated sensitivity to an otherwise harmless antigen in the environment, allergens.

Some of the newly produced B cells are short-lived cells that have ______________________________.

an immediate effect against the antigen and are therefore called effector cells

Any molecule that triggers an immune response:

antigen

Once a pathogen enters the body, __________________________________________________________.

antigens on its surface bind with a B cell that has complimentary antigen receptors.

Hodgkin's disease, a type of cancer that affects lymphocytes, ______________________________. Radiation therapy and drug treatments used against many cancers can have the same effect.

can depress the immune system.

Antibodies also aid in pathogen destruction. The binding of antibodies to antigens on the surface of pathogens can also result in clumps that are easily engulfed by _________________.

circulating phagocytic cells.

Thus, _____________ produces not only cells that will fight the first exposure to an antigen (effector cells) but also cells that will respond to future exposures (memory cells).

clonal selection

Binding of an antigen triggers production of an army of immune cells:

clonal selection.

The binding activates the B cell, causing it to grow, divide, and develop further. This produces____________________________________________.

clones of B cells specialized for defending against the very antigen that triggered the response.

By secreting antibodies into the blood and lymph, B cells defend primarily against pathogens circulating in body fluids. The information for making a specific antibody is __________________________.

coded within the DNA in the nucleus of a B cell.

While the antibody response from B cells helps to eliminate pathogens in the blood and lymph, the _______________ destroys pathogens within body cells.

cytotoxic T cell.

Antibodies:

defensive proteins that bind antigens.

Histamine causes blood vessels to

dilate and leak fluid, which results in nasal irritation, itchy skin, and tears.

To minimize organ rejection, ___________________________________________________________. Drugs are administered to suppress the immune response.

doctors look for donors with self-proteins that match the recipient's as closely as possible.

Antihistamines

drugs that interfere with histamine's action and give temporary relief from an allergy.

Immune cells that secrete antibodies or destroy pathogens:

effector cells.

The human immunodeficiency virus (HIV) causes ___________________. If not treated, HIV results in acquired immune deficiency syndrome (AIDS) ,causing __________________ which could be fatal.

helper T cells to decline significantly, a person to completely lack an immune system.

HIV is deadly because __________________________.

it destroys the immune system, leaving the body defenseless against most invaders.

The unique shape of the antigen and the complementary antigen receptor on the B cell results in a ____________________ fit that activates the B cell.

lock and key.

The immune system's ability to remember prior infection provides __________________________________________.

long-term protection against many diseases.

The fluid that is found within the lymphatic vessels is known as

lymph.

Each helper T cell only recognizes a specific antigen fragment displayed on self-proteins. Helper T cells are only activated when _______________________________________.

particular white blood cell types "advertise" the antigen.

The fragments of antigens that T cells recognize originate from ____________ that have entered body cells. __________ inside the body cell breakdown the pathogen into fragments.

pathogens, Enzymes.

Phagocytes of the internal innate defenses that migrate into the lymphatic system are one of the cell types capable of presenting antigens to helper T cells, thus, _____________________________________________________.

phagocytes provide a direct link between innate immunity, adaptive immunity, and the lymphatic system.

During the first response to an antigen, called the ________________, it takes several days for clonal selection to produce effector cells. The primary immune response peaks about two to three weeks after the first exposure, at which point it starts to decline.

primary immune response.

In multiple sclerosis (MS), T cells wrongly attack proteins in neurons, often causing _________________.

progressive muscle paralysis.

The activated cell synthesizes and discharges several ________ that enter the cell, and trigger the death of the cell.

proteins

Antigen receptors on B cells specialize in:

recognizing intact antigens that are on the surface of pathogens or circulating freely in body fluids.

Memory cells are long-lived cells found in the lymph nodes, ready to attack should a "known" antigen infect the body again. If memory cells are exposed to a previously encountered antigen, they rapidly give rise to new effector cells and memory cells, a process known as the ______________.

secondary immune response.

Vaccination induces the primary immune response that produces memory cells. An encounter with the pathogen later in life then elicits a rapid and strong ___________.

secondary response.

The symptoms of an allergy result from a two-stage reaction. The first stage, called _____________, occurs when a person is first exposed to an allergen.

sensitization

Some people are extremely sensitive to certain allergens. Any contact with these allergens causes a sudden release of inflammatory chemicals. Blood vessels dilate abruptly, causing a rapid and potentially fatal drop in blood pressure, a condition called __________.

shock.

Immunodeficient people lack one or more components of the immune system and are therefore _______________.

susceptible to infections that would not ordinarily cause a problem.

Because allergens usually enter the body through the nose and throat, ________________.

symptoms are often most prominent there.

Immunity is obtained after infection but it can also be achieved artificially by ______________ (also called immunization).

vaccination