Chapter 20 - Immune System Flashcards

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1
Q

Any Disease causing agent is called?

A

A Pathogen

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2
Q

Immune System

A

Theimmune systemis a host defense system. It comprises many biological structures—ranging from individual white blood cells to entire organs — as well as many complex biological processes. The function of the immune system is to protect the host from pathogens and other causes of disease such as tumor cells. To function properly, the immune system must be able to detect a wide variety of pathogens. It also must be able to distinguish the cells of pathogens from the host’s own cells and also to distinguish cancerous or damaged host cells from healthy cells.

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3
Q

Innate Immune System

A

The innate immune system provides very quick but non-specific response to pathogens. It responds the same way regardless of the type of pathogen that is attacking the host. It includes barriers — such as the skin and mucous membranes—that normally keep pathogens out of the body. It also includes general responses to pathogens that manage to breach these barriers, including chemicals and cells that attack the pathogens inside the human host.

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4
Q

Adaptive Imune System and Immunity

A

The adaptive immune system is activated if pathogens successfully enter the body and manage to evade the general defenses of the innate immune system. An adaptive response is specific to the particular type of pathogen that has invaded the body or to cancerous cells. It takes longer to launch a specific attack, but once it is underway, its specificity makes it very effective. An adaptive response also usually leads to immunity. This is a state of resistance to a specific pathogen due to the ability of the adaptive immune system to “remember” the pathogen and immediately mount a strong attack tailored to that particular pathogen if it invades again in the future.

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5
Q

Self, Nonself, and MHC

A

Virtually all body cells have surface proteins that are part of a complex calledmajor histocompatibility complex (MHC). These proteins are one way the immune system recognizes body cells as self. Non-self proteins, in contrast, are recognized as foreign because they are different from self proteins.

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6
Q

What do B cells do?

A

They respond to foreign antigens by producing antibodies.

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7
Q

What is an antigen and an antibody?

A

Many non-self molecules comprise a class of compounds called antigens. Antigens, which are usually proteins, bind to specific receptors on immune system cells and elicit an adaptive immune response.

An antibody is a molecule that precisely matches and binds to a specific antigen. This may target the antigen (and the pathogen displaying it) for destruction by other immune cells.

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8
Q

Immune Surveillance

A

Another important role of the immune system is to identify and eliminate tumor cells. This is calledimmune surveillance.The transformed cells of tumors express antigens that are not found on normal body cells. The main response of the immune system to tumor cells is to destroy them. This is carried out primarily by aptly named killer T cells of the adaptive immune system.

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9
Q

Lymphatic System

A

The lymphatic system is a human organ system that is a vital part of the adaptive immune system.

The lymphatic system consists of several lymphatic organs and a body-wide network of lymphatic vessels that transport the fluid called lymph. Lymph is essentially blood plasma that has leaked from capillaries into tissue spaces. It includes many leukocytes, especially lymphocytes, which are the major cells of the lymphatic system. Like other leukocytes, lymphocytes defend the body. There are several different types of lymphocytes that fight pathogens or cancer cells as part of the adaptive immune system.

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10
Q

Major organs in the lymphatic system?

A

Major lymphatic organs include the thymus and bone marrow. Their function is to form and/or mature lymphocytes. Other lymphatic organs include the spleen, tonsils, and lymph nodes, which are small clumps of lymphoid tissue clustered along lymphatic vessels. These other lymphatic organs harbor mature lymphocytes and filter lymph. They are sites where pathogens collect and adaptive immune responses generally begin.

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11
Q

Neuroimmine system:

A

Protects brain and spinal cord with blood-brain and blood-spinal cord barriers.

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12
Q

Neuroimmune system is generally considered to be ____ from the peripheral immune system which is the ___ immune system

A

distinct, main

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13
Q

Neuroimmine Cells

A

Unlike the peripheral system, in which leukocytes are the main cells, the main cells of the neuroimmune system are thought to be nervous system cells called glial cells. These cells are able to recognize and respond to pathogens, debris, and other potential dangers. Types of glial cells involved in neuroimmune responses include microglial cells and astrocytes.

Microglial cells are among the most prominent types of glial cells in the brain. One of their main functions is to phagocytize cellular debris that remains when neurons die. Microglial cells also “prune” obsolete synapses between neurons.

Astrocytes are glial cells that have a different immune function. They allow certain immune cells from the peripheral immune system to cross the blood-brain barrier into the brain to target both pathogens and damaged nervous tissue.

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14
Q

What do Killer T cells do?

A

Tumor surveillance.
Then DESTROY THEM.

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15
Q

What is the lymphatic system?

A

Thelymphatic systemis a collection of organs involved in the production, maturation, and harboring of white blood cells called lymphocytes. It also includes a network of vessels that transport or filter the fluid known aslymphin which lymphocytes circulate.

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16
Q

Lacteals, Villus, and Chyle

A

Lymphatic vessels called lacteals are present in the lining of the gastrointestinal tract, mainly in the small intestine. Each tiny villus in the lining of the small intestine has an internal bed of capillaries and lacteals. The capillaries absorb most nutrients from the digestion of food into the blood. The lacteals absorb mainly fatty acids from lipid digestion into the lymph, forming a fatty-acid-enriched fluid called chyle. Vessels of the lymphatic network then transport chyle from the small intestine to the main lymphatic ducts in the chest from which it drains into the blood circulation. The nutrients in chyle then circulate in the blood to the liver, where they are processed along with the other nutrients that reach the liver directly via the bloodstream.

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17
Q

What are Lymphocytes?

A

Lymphocytesare leukocytes that are involved in the adaptive immune system. They are responsible for the recognition of, and tailored defense against, specific pathogens or tumor cells. Lymphocytes may also create a lasting memory of pathogens so they can be attacked quickly and strongly if they ever invade the body again. In this way, lymphocytes bring about long-lasting immunity to specific pathogens.

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18
Q

What is the primary function of the lymphatic system?

A

The primary function of the lymphatic system is host defense as part of the immune system. This function of the lymphatic system is centered on the production, maturation, and circulation of lymphocytes.

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19
Q

What are the 2 types of lymphocytes and what do they do?

A

B (cells) Lympocytes - B cells mature in the bone marrow, which is why they are called B cells. After they mature and leave the bone marrow, they travel first to the circulatory system and then enter the lymphatic system to search for pathogens.

T (cells) Lymphocytes - T cells, on the other hand, mature in the thymus, which is why they are called T cells. The Thymus is a small lymphatic organ in the chest that consists of an outer cortex and inner medulla, all surrounded by a fibrous capsule. After maturing in the thymus, T cells enter the rest of the lymphatic system to join B cells in the hunt for pathogens.

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20
Q

The bone marrow and thymus are called primary organs because of their role in the production and/or maturation of lymphocytes.

A

lymphoid

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21
Q

The tonsils, spleen, and lymph nodes are referred to as ____ ____organs. These organs do not produce or mature lymphocytes. Instead, they filter lymph and store lymphocytes.

A

secondary lymphoid

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22
Q

TONSILS?!!?!!

A

There are actually four pairs of human tonsils. The fourth pair, called tubal tonsils, is located at the back of the nasopharynx. The palatine tonsils are the tonsils that are visible on either side of the throat. All four pairs of tonsils encircle a part of the anatomy where the respiratory and gastrointestinal tracts intersect and where pathogens have ready access to the body. This ring of tonsils is called Waldeyer’s ring.

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23
Q

SPLEEN
Oh my SPLEEEENNN!!!

A

Thespleen(pictured below) is the largest of the secondary lymphoid organs and is centrally located in the body. Besides harboring lymphocytes and filtering lymph, the spleen also filters blood. Most dead or aged red blood cells are removed from the blood in the red pulp of the spleen. Lymph is filtered in the white pulp of the spleen. In the fetus, the spleen has the additional function of producing red blood cells. This function is taken over by bone marrow after birth.

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24
Q

Lymph Nodes

A

Eachlymph nodeis a small but organized collection of lymphoid tissue that contains many lymphocytes. Lymph nodes are located at intervals along the lymphatic vessels, and lymph passes through them on its way back to the blood.

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25
Q

Lymphocyte Training Program

A

All lymphocytes are produced in bone marrow and then go through a process of maturation in which they “learn” to distinguish self from non-self.

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26
Q

Something to know about the Innate Immune System

A

Although the innate immune system provides immediate and rapid defenses against pathogens, it does not confer long-lasting immunity to them. In most organisms, the innate immune system is the dominant system of host defense.

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27
Q

Measures of the Innate Immune System

A

In humans, the innate immune system includes surface barriers, inflammation, the complement system, and a variety of cellular responses.

28
Q

3 types of pathogen barriers:

A

Mechanical - Physically block Pathogens. Skin (Epidermis), Hair, Mucous Membranes, tears, urine.

Chemical - Destroy pathogens. Sweatm musuc, tears, saliva, breastmilk , urine, vaginal secretions, semen, stomach acid.

Biological - lving organisms that protect the body from pathogens. Harmless Bacteria.

29
Q

Function of Inflammation:

A

The main function of inflammation is to establish a physical barrier against the spread of infection. It also eliminates the initial cause of cell injury, clears out dead cells and tissues damaged from the original insult and the inflammatory process, and initiates tissue repair. Inflammation is often a response to infection by pathogens, but there are other possible causes, including burns, frostbite, and exposure to toxins.

30
Q

Symptoms of Inflammation

A

The signs and symptoms of inflammation include redness, swelling, warmth, pain, and frequently some loss of function. These symptoms are caused by increased blood flow into infected tissue and a number of other processes.

31
Q

The COMPLEMENT system

A

Thecomplement systemis a complex biochemical mechanism named for its ability to “complement” the killing of pathogens by antibodies, which are produced as part of an adaptive immune response. The complement system consists of more than two dozen proteins that are normally found in the blood and synthesized in the liver. The proteins usually circulate as non-functional precursor molecules until activated.

32
Q

Phagocytosis:

A

Phagocytosis is an important feature of innate immunity that is performed by cells classified as phagocytes. In the process of phagocytosis, phagocytes engulf and digest pathogens or other harmful particles.

33
Q

Steps of phagocytosis

A

when a pathogen such as a bacterium is encountered by a phagocyte, the phagocyte extends a portion of its plasma membrane, wrapping the membrane around the pathogen until it is enveloped. Once inside the phagocyte, the pathogen becomes enclosed within an intracellular vesicle called a phagosome. The phagosome then fuses with another vesicle called a lysosome, forming a phagolysosome. Digestive enzymes and acids from the lysosome kill and digest the pathogen in the phagolysosome. The final step of phagocytosis is excretion of soluble debris from the destroyed pathogen through exocytosis.

34
Q

Neutrophil Facts

A

Neutrophils are leukocytes that travel throughout the body in the blood and are usually the first immune cells to arrive at the site of an infection. They are the most numerous types of phagocytes and normally make up at least half of the total circulating leukocytes. . .Many neutrophils are needed to fight infections because after a neutrophil phagocytizes just a few pathogens, it generally dies.

35
Q

Macrophages:

A

Macrophages are large phagocytic leukocytes that develop from monocytes. Macrophages spend much of their time within the interstitial fluid in tissues of the body. They are the most efficient phagocytes and can phagocytize substantial number of pathogens or other cells. Macrophages are also versatile cells that produce a wide array of chemicals—including enzymes, complement proteins, and cytokines — in addition to their phagocytic action. As phagocytes, macrophages act as scavengers that rid tissues of worn-out cells and other debris as well as pathogens. In addition, macrophages act as antigen-presenting cells that activate the adaptive immune system.

36
Q

Eosinophils:

A

Eosinophils are non-phagocytic leukocytes that are related to neutrophils. They specialize in defending against parasites. They are very effective in killing large parasites such as worms by secreting a range of highly toxic substances when activated. Eosinophils may become overactive and cause allergies or asthma.

37
Q

Basophils

A

Basophils are non-phagocytic leukocytes that are also related to neutrophils. They are the least numerous of all white blood cells. Basophils secrete two types of chemicals that aid in body defenses: histamines and heparin. Histamines are responsible for dilating blood vessels and increasing their permeability in inflammation. Heparin inhibits blood clotting and also promotes the movement of leukocytes into an area of infection.

38
Q

Dendritic Cells

A

Like macrophages, dendritic cells develop from monocytes. They reside in tissues that have contact with the external environment, so they are located mainly in the skin, nose, lungs, stomach, and intestines. Besides engulfing and digesting pathogens, dendritic cells also act as antigen-presenting cells that trigger adaptive immune responses.

39
Q

Mast Cells

A

Mast cells are non-phagocytic leukocytes that help to initiate inflammation by secreting histamines. In some people, histamines trigger allergic reactions as well as inflammation. Mast cells may also secrete chemicals that help defend against parasites.

40
Q

Natural Killer Cells???

A

Natural killer cells are in the subset of leukocytes called lymphocytes, which are produced by the lymphatic system. Natural killer cells destroy cancerous or virus-infected host cells, although they do not directly attack invading pathogens. Natural killer cells recognize these host cells by a condition they exhibit called “missing self.” Cells with missing self have abnormally low levels of cell-surface proteins of the major histocompatibility complex (MHC), which normally identify body cells as self.

41
Q

Ways that pathogens evade the immune system:

A

-hide in host cells
-protective capsule
-mimick host cells
-kill phagocytes
-prevent the formation of immune chemicals
-form complex biofilm to block immune cells.

42
Q

T Lymphocyte subtypes

A

There are multiple types ofT cells,or T lymphocytes. Major types are killer (or cytotoxic) T cells and helper T cells. Both types develop from immature T cells that become activated by exposure to an antigen.

43
Q

T Cell Activation

A

T cells must be activated to become either killer T cells or helper T cells. This requires presentation of a foreign antigen by antigen-presenting cells. Antigen-presenting cells may be dendritic cells, macrophages, or B cells. Activation occurs when T cells are presented with a foreign antigen coupled with an MHC self antigen. Helper T cells are more easily activated than killer T cells. Activation of killer T cells is strongly regulated and may require additional stimulation from helper T cells.

44
Q

Helper T Cells

A

Activated helper T cells do not kill infected or cancerous cells. Instead, their role is to “manage” both innate and adaptive immune responses by directing other cells to perform these tasks. They control other cells by releasing cytokines. These are proteins that can influence the activity of many cell types, including killer T cells, B cells, and macrophages. For example, some cytokines released by helper T cells help activate killer T cells

45
Q

B Cells

A

B cells, or B lymphocytes, are the major cells involved in the creation of antibodies that circulate in blood plasma and lymph. Antibodies are large, Y-shaped proteins used by the immune system to identify and neutralize foreign invaders. Besides producing antibodies, B cells may also function as antigen-presenting cells or secrete cytokines that help control other immune cells and responses.

46
Q

B Cell Activation

A

Before B cells can actively function to defend the host, they must be activated. B cell activation begins when a B cell engulfs and digests an antigen. The antigen may be either free floating in the lymph or it may be presented by an antigen-presenting cell such as a dendritic cell or macrophage. In either case, the B cell then displays antigen fragments bound to its own MHC antigens. The MHC-antigen complex on the B cell attracts helper T cells. The helper T cells, in turn, secrete cytokines that help the B cell to multiply and the daughter cells to mature into plasma cells.

47
Q

Plasma Cells

A

Plasma cells are antibody-secreting cells that form from activated B cells. Each plasma cell is like a tiny antibody factory. It may secrete millions of copies of an antibody, each of which can bind to the specific antigen that activated the original B cell. The specificity of an antibody to a specific antigen is illustrated in the figure below. When antibodies bind with antigens, it makes the cells bearing them easier targets for phagocytes to find and destroy. Antibody-antigen complexes may also trigger the complement system of the innate immune system, which destroys the cells in a cascade of protein enzymes. In addition, the complexes are likely to clump together (agglutinate). If this occurs, they are filtered out of the blood in the spleen or liver

48
Q

Memory cells

A

Most activated T cells and B cells die within a few days once a pathogen has been cleared from the body. However, a few of the cells survive and remain in the body as memory T cells or memory B cells. These memory cells are ready to activate an immediate response if they are exposed to the same antigen again in the future. This is the basis ofimmunity.

49
Q

Active Immuity

A

Active immunityis the ability of the adaptive immune system to resist a specific pathogen because it has formed an immunological memory of the pathogen

50
Q

Naturally acquired adaptive immunity

A

Active immunity is acquired naturally when a pathogen invades the body and activates the adaptive immune system. When the initial infection is over, memory B cells and memory T cells remain that provide immunological memory of the pathogen.

51
Q

Artificially acquired Active Immunity

A

Active immunity can also be acquired artificially through immunization.Immunizationis the deliberate exposure of a person to a pathogen in order to provoke an adaptive immune response and the formation of memory cells specific to that pathogen.

52
Q

Vaccine

A

In avaccine,only part of a pathogen, a weakened form of the pathogen, or a dead pathogen is typically used. This causes an adaptive immune response without making the immunized person sick. This is how you most likely became immune to diseases such as measles, mumps, and chicken pox.

53
Q

Passive Immunity

A

Passive immunityresults when pathogen-specific antibodies or activated T cells are transferred to a person who has never been exposed to the pathogen. Passive immunity provides immediate protection from a pathogen, but the adaptive immune system does not develop immunological memory to protect the host from the same pathogen in the future. Unlike active immunity, passive immunity lasts only as long as the transferred antibodies or T cells survive in the blood. This is usually between a few days and a few months. However, like active immunity, passive immunity can be acquired both naturally and artificially.

54
Q

Naturally acquired Passive Immunity

A

Passive immunity is acquired naturally by a fetus through its mother’s blood. Antibodies are transported from mother to fetus across the placenta, so babies have high levels of antibodies at birth. Their antibodies have the same range of antigen specificities as their mother’s. Passive immunity may also be acquired by an infant through the mother’s breast milk. This gives young infants protection from common pathogens in their environment while their own immune system matures.

55
Q

Artificially acquired passive immunity

A

Older children and adults can acquire passive immunity artificially through the injection of antibodies or activated T cells. This may be done when there is a high risk of infection and insufficient time for the body to develop active immunity through vaccination. It may also be done to reduce symptoms of ongoing disease or to compensate for immunodeficiency diseases

56
Q

How do certain pathogens live for long periods of time?

A

-antigenic variation
-mask antigens with host molecules

57
Q

Allergies

A

Anallergyis a disorder in which the immune system makes an inflammatory response to a harmless antigen. It occurs when the immune system is hypersensitive to an antigen in the environment that causes little or no response in most people.

58
Q

Allergens

A

Any antigen that causes an allergy is called anallergen.Common allergens are plant pollens, dust mites, mold, specific foods (such as peanuts or shellfish), insect stings, and certain common medications (such as aspirin and penicillin). Allergens may be inhaled or ingested, or they may come into contact with the skin or eyes.

59
Q

ANAPHYLAXIS

A

The most severe allergic reaction is a systemic reaction calledanaphylaxis.This is a life-threatening response caused by a massive release of histamines. Many of the signs and symptoms of anaphylaxis are shown in the figure below. Some of them include a drop in blood pressure, changes in heart rate, shortness of breath, and swelling of the tongue and throat, which may threaten the patient with suffocation unless emergency treatment is given

60
Q

Allergy Immunotherapy

A

Another way to treat allergies is calledimmunotherapy,commonly called “allergy shots.” This approach may actually cure specific allergies, at least for several years if not lifelong. It may be particularly beneficial for allergens such as pollen that are difficult or impossible to avoid. First, however, patients must be tested to identify the specific allergens that are causing their allergies

61
Q

Autoimmune Diseases

A

Autoimmune diseasesoccur when the immune system fails to recognize the body’s own molecules as self. As a result, instead of ignoring the body’s healthy cells, it attacks them, causing damage to tissues and altered organ growth and function. Most often, it is B cells that are at fault in autoimmune responses. They are generally the cells that lose tolerance for self.

62
Q

Treating Autoimmune Disease

A

None of these common autoimmune diseases can be cured, although all of them have treatments that may help relieve symptoms and prevent some of the long-term damage they may cause. Traditional treatments for autoimmune diseases include immunosuppressive drugs to block the immune response and anti-inflammatory drugs to quell inflammation. Hormone replacement may be another option. For example, type I diabetes is treated with injections of the hormone insulin because islet cells in the pancreas can no longer secrete it.

63
Q

Immunodeficiency

A

Immunodeficiencyoccurs when the immune system is not working properly, generally because one or more components of the immune system are inactive. As a result, the immune system may be unable to fight off pathogens or cancers that a normal immune system would be able to resist. Immunodeficiency may occur for a variety of reasons.

64
Q

Human immunodeficiency virus (HIV)is the ___ ____ cause of immunodeficiency in the world today,

A

most common

65
Q

HIV vs Helper T Cells

A

HIV infects and destroys helper T cells, the type of lymphocytes that regulate the immune response. How this occurs is shown in the diagram below. The virus injects its own DNA into a helper T cell and uses the T cell’s “machinery” to make copies of itself. In the process, the helper T cell is destroyed, and the virus copies go on to infect other helper T cells. HIV is able to evade the immune system and keep destroying helper T cells by mutating frequently so its surface antigens keep changing and by using the host cell’s membrane to hide its own antigens.

66
Q

AIDS

A

Acquired immunodeficiency syndrome (AIDS)may result from years of damage to the immune system by HIV. It occurs when helper T cells fall to a very low level and opportunistic diseases occur. Opportunistic diseases are infections and tumors that are rare except in people with a damaged immune system. The diseases take advantage of the “opportunity” presented by people whose immune system cannot fight back. Opportunistic diseases are usually the direct cause of death of people with AIDS.

67
Q

Treating HIV/AIDS

A

For patients who have access to HIV medications, infection with the virus has ceased to be the death sentence that it once was. By 1995, combinations of drugs called “highly active antiretroviral therapy” were developed. For some patients, these drugs can reduce the amount of virus they are carrying to undetectable levels. However, some amount of virus always hides in the body’s immune cells and will multiply again if a patient stops taking the medications. Researchers are trying to develop drugs to kill these hidden viruses as well. If their efforts are successful, it could bring an end to AIDS.