The immune SystemCh 37

VOCABULARY1. pathogen,

2. infectious disease,

3. reservoir,

4. endemic,

5. epidemic,

6. pandemic,

7. antibiotic,

8. lymphocytes,

9. antibodies,

10.immunization

pathogen

• Things that cause infectious diseases such as bacteria, viruses protozoan, fungi and parasites

infectious disease,

• A disease caused by a pathogen passed from one organism to another disrupting homeostasis

reservoir,

• The source of the pathogen in the environment

• Animals, people inanimate objects soil

endemic,

• When a disease is found continually in small amounts within a population

epidemic,

Outbreaks of a disease that afflict many people

pandemic,

• Widespread epidemics covering large areas of a continent or the entire world

antibiotic,

• Drugs that kill or inhibit the growth of bacterial pathogens

lymphocytes,

• A type of white blood cell made in the bone marrow

antibodies,

• Proteins made by B lymphocytes that specifically react with foreign antigens

immunization

• Deliberate exposure to an antigen so a primary response immunity and memory cells will develop

• What are some examples of pathogens that cause infectious diseases?

• Bacteria, fungi, protozoan, viruses

bacterial

• Strep and staph

Protozoan

• Malaria

• Trypanosoma

Fungal

• Ringworm

• Tinea/ athletes foot

• What is the germ theory? That microorganisms cause disease!

• Robert Koch’s experiment with anthrax led to a set of steps known as Koch’s postulates. Summarize the steps and describe their purpose

• 1. isolate the suspected pathogen

• 2. grow the isolated pathogen

• 3. place the isolated pathogen in a healthy host to see if it causes the disease

• 4. re isolate the pathogen from the newly infected host.

• Give some examples of reservoirs of pathogens

• People , soil, animals, objects

• Differentiate between the three main methods of pathogen transmission.

• 1.direct • 2. indirect• 3. vectors

• Based on the above methods of transmission, what are some precautions we can take to prevent infection?

• Hand washing, keeping hands out of mouths and eyes, sanitation of water and food, surface of objects sanitized, control of insects and other arthropods quarantine of individuals who are known to have a disease

• How has the widespread use of antibiotics caused many bacteria to become resistant to antibiotics?

• Natural selection! The overuse leads to the ones who are naturally resistant surviving and reproducing producing strains of bacteria that are resistant to the antibiotics.

Antibiotics

• Used only for bacterial diseases! They interfere with protein synthesis or cell wall formation for prokaryotes.

• Take them all to prevent resistant strains forming!

• Do not take them if you have a virus! They will not help!!!

• Ex. Penicillin, erythromycin and neomycin

Antibiotics

• Antibiotics are powerful medicines that fight bacterial infections. They do NOT work on viral or fungal infections!!!

How do Antibiotics work?

1. Inhibition of Cell Wall Synthesis (most common mechanism) ex. Vancomycin, Bacitracin

2. Inhibition of Protein Synthesis (Translation) (second largest class) ex.Tetracyclines Macrolides, Clindamycin

3. Alteration of Cell Membranes ex.Bacitracin (topical) 4. Inhibition of Nucleic Acid Synthesis ex. Metronidazole, Bacitracin (topical) 5. Antimetabolite Activity ex. Sulfonamides & Dapsone

• Why are antibiotics not effective against viruses?

• Antibiotics attack the cell wall of prokaryotes, viruses do NOT have a cell wall!

• What is nonspecific immunity?

• General defenses against any pathogen, not a specific one!

• First line of defense

• Usually trying to prevent disease

• What are some of the body’s barriers against infection?

• Skin, chemical barriers, mucus, saliva, cilia, tears

• 4. In the following chart, list five examples of barrier defenses and how they work.

• Mucous membranes Mucus, a viscous fluid, enhances defenses by trapping microbes and other particles.

• Saliva, tears Bathe various exposed epithelia, providing a washing action that also inhibits colonization by fungi and bacteria

• Stomach acid Kills most of the microbes in food and water before they can enter the intestines

• Secretions from oil and sweat glands

• Give human skin a pH ranging from 3 to 5, acidic enough to prevent the growth of many bacteria

• Skin: Blocks entry of many pathogens

• 1. We first encountered phagocytosis in Concept 7.5, but it plays an important role in the immune systems of both invertebrates and vertebrates. Review the process by briefly explaining the six steps to ingestion and destruction of a microbe by a phagocytic cell.

• 1. Pseudopodia surround pathogens.

• 2. Pathogens are engulfed by endocytosis.

• 3. Vacuole forms, enclosing pathogens.

• 4. Vacuole and lysosome fuse.

• 5. Toxic compounds and lysosomal enzymes destroy pathogens.

• 6. Debris from pathogens is released by exocytosis.

Figure 43.3

Pathogen

PHAGOCYTICCELL

VacuoleLysosomecontainingenzymes

• 2. Explain the role of the Toll receptor in producing antimicrobial peptides.

• Signal transduction from the Toll receptor to the cell nucleus leads to synthesis of a set of antimicrobial peptides active against fungi.

• 3. List the three innate defenses vertebrates share with invertebrates and the two defenses unique to vertebrates.

• Vertebrates and invertebrates alike share the innate defenses of barrier defenses, phagocytosis, and antimicrobial peptides.

• Vertebrates alone have natural killer cells, inflammatory response, and interferons.

Non specific immunity• It also includes internal responses that are not

specific to the invader such as white blood cells that engulf microorganisms by phagocytosis (neutrophils and macrophages)

• Complement: proteins that help the cell destroy invaders.

• Interferon: Proteins that prevent viral replication• Inflammatory response: Increased blood flow,

increased white blood cells, raised temperature all create a hostile environment for the invaders! Pain, heat and redness from infection are a sign of inflammation!

6. In the chart below, explain the role of the four phagocytic cells

• Non specific: recognize as WBC’s used as phagocytes.

• Neutrophils Circulate in the blood, are attracted by signals from infected tissues and then engulf and destroy the infecting pathogens

• Macrophages Some migrate throughout the body, whereas others reside permanently in organs and tissues where they are likely to encounter pathogens.

• Dendritic cells Populate tissues, such as skin, that contact the environment. They stimulate adaptive immunity against pathogens they encounter and engulf.

• Eosinophils Often found beneath mucosal surfaces, have low phagocytic activity but are important in defending against multicellular invaders, such as parasitic worms

The inflammatory response

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• 10. Use the following figure to explain the three steps of an inflammatory response.

• See page 934 of your text for the labeled figure.• 1. At the injury site, mast cells release histamines,

and macrophages secrete cytokines. These signaling molecules cause nearby capillaries to dilate.

• 2. Capillaries widen and become more permeable, allowing fluid containing antimicrobial peptides to enter the tissue. Signals released by immune cells attract neutrophils.

• 3. Neutrophils digest pathogens and cell debris at the site, and the tissue heals.

Figure 43.8-3

Pathogen Splinter

Mastcell

Macro-phage

Capillary

Redblood cells

Neutrophil

Signalingmolecules

Movementof fluid

Phagocytosis

Complement system (non)

 • If germs get through the body's physical

and chemical barriers ( the Non specific immunity) into the bloodstream, a mixture of liquid proteins called complement is activated and attacks them. The complement system includes a series of proteins.

• While there are millions of different antibodies in your blood stream, each sensitive to a specific antigen, there are only a handful of proteins in the complement system. They float freely in your blood.

• Complements are manufactured in the liver. The complement proteins are activated by and work with (complement) the antibodies.

• They cause lysing (bursting) of cells and signal to phagocytes that a cell needs to be removed.

 

• 9. Explain the role of the following two antimicrobial compounds

• complement: Consists of roughly 30 proteins in blood plasma. These proteins circulate in an inactive state and are activated by substances on the surface of many microbes. Activation results in a cascade of biochemical reactions that can lead to lysis of invading cells.

Interferon ( non)

• Interferon is another type of protein produced by most cells in the body. The job of interferon is to let cells signal one another. When a cell detects interferon from other cells, it produces proteins that help prevent viral replication in the cell and also stimulates killer cells.

• 9. Explain the role of the following two antimicrobial compounds.

• interferon: Proteins that provide innate defense by interfering with viral infections. Virus-infected

• body cells secrete interferons, which induce nearby uninfected cells to produce substances that inhibit viral reproduction. In this way, interferons limit the cell-to-cell spread of viruses in the body, helping control viral infections such as colds and influenza.

Hormone (non)

• There are several hormones generated by the immune system. These hormones are generally known as lymphokines.

• Some hormones in the body suppress the immune system. These are the steroids and corticosteroids (components of adrenaline. This is why taking some steroids can make you more susceptible to getting an infection!

• Describe the following non-specific responses:

• a. Cellular defense: phagocytosis of pathogens by macrophages. Complement proteins that help the phagocytosis process

• b. Interferon: a chemical released by cells infected by a virus. It stimulates the cells to release anti viral proteins to keep the virus from replicating.

• c. Inflammatory Response: increased blood flow: redness and heat. Increased permeability of vessels: pus, wbc’ to kill pathogens

• What is specific immunity?

• 15. The following brief questions will serve as a beginning primer for immune system recognition.

• a. What is an antigen?

• A substance that elicits an immune response by binding to receptors of B cells, antibodies, or of T cells.

Figure 43.UN01

Antigen receptors

Mature B cell Mature T cell

• B cells and T cells have receptor proteins that can bind to foreign molecules

• Each individual lymphocyte is specialized to recognize a specific type of molecule

© 2011 Pearson Education, Inc.

• b. What is the relationship between an antigen receptor, an antibody, and an immunoglobin?

• An antigen receptor is a general term for a surface protein, located on B cells and T cells, that binds to antigens, initiating adaptive immune responses.

• An antibody is a protein secreted by plasma cells (differentiated B cells) that binds to a particular antigen; also called immunoglobulin.

Figure 43.10a

AntibodyAntigenreceptor

B cell

Antigen Epitope

Pathogen

(a) B cell antigen receptors and antibodies

• c. How is an epitope related to an antigen? (Look at Figure 43.10 in your text.)

• An epitope is the accessible portion of an antigen that binds to an antigen receptor. It is also known as an antigenic determinant.

Specific Immunity

• If things get past the non specific line of defense…

• The Lymphatic System has items designed to attack specific invaders!

• B-Cells produce antibodies made in response to specific antigens ( invaders)

• T-cells: Also are specific to antigens produce cytotoxic T cells that destroy pathogens.

Lymphatic system• Lymph nodes are basically filters that trap germs and other

foreign bodies.

• The nodes have armies of lymphocytes to deal with the germs. Lymphocytes are a type of white blood cell, which neutralizes or destroys germs.

• The lymph nodes can become swollen when fighting an infection.

• That’s why the doctor feels your arm pits and groin area during an exam!

• Lymphoid organs include the bone marrow and the thymus, as well as lymph nodes, spleen, tonsils and adenoids, the appendix, and clumps of lymphoid tissue in the small intestine known as Peyer's patches.

• There are about 2 to 4 pints of lymph fluid in the average body.

Thymus

Peyer’spatches(smallintestine)

Appendix(cecum)

AdenoidTonsils

Lymphaticvessels

Spleen

Lymphnodes

Lymphnode

Bloodcapillary

Interstitialfluid

Tissuecells

Lymphatic vessel

Lymphatic vessel

Masses ofdefensive cells

Figure 43.7

Spleen • The spleen filters the blood

looking for foreign cells and removes old red blood cells. It is an organ about the size of a fist in the upper left of the abdomen.

• It contains two main types of tissue: red tissue that disposes of the worn-out blood cells, and white tissue that contains lymphoid tissue.

• Different part of the spleen specialize in different kinds of immune cells. When microorganisms get carried by the blood into the red tissue, they become trapped by the immune cells known as macrophages.

Thymus

• The thymus is located in your chest, between your breast bone and your heart. It is responsible for producing T-cells and is important for T cell maturation.

• What is the function of the lymphatic system?

• Filters blood, destroys foreign microorganisms, absorbs fat, returns excess fluids to the circulatory system

• What are some of the organs of the lymphatic system?

• Lymph tissue, fluid, nodes, vessels, tonsils, spleen and thymus

Antibodies (specific) • Antibodies (also referred to as

immunoglobulins and gammaglobulins) are are Y-shaped proteins that respond to specific bacteria, viruses or toxins, called antigens. They are produced by white blood cells.

• Antibodies can bind to toxins, disabling their chemical actions or signal that an invader needs to be removed.

• These antibodies are divided into five classes. Their names are generally abbreviated. For instance, Immunoglobulin A is abbreviated IgA.

• Here are all of the abbreviations: IgA, IgD, IgE, IgG, i IgM.

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White blood cells/Leukocytes • White blood cells are a very important part of your immune system. They are actually a large

collection of different cells that work together to destroy bacteria and viruses. They act like independent, living single-cell organisms that can move like amoeba and capture things on their own by engulfing them. Most of them are created in the bone marrow and start out as stem cells.

• Leukocytes • Lymphocyte • Monocytes • Granulocytes • B-cells • Plasma cells • T-cells • Helper T-cells • Killer T-cells • Suppressor T-cells • Natural killer cells • Neutrophils • Eosinophils • Basophils • Phagocytes • Macrophages

There are three types of Leukocytes:

• Granulocyteswhich comprise 50 to 60 percent of all leukocytes. They are further divided into three types of Granulocytes: Neutrophils, Eosinophils and Basophils. Granulocytes get their name because they contain granules. These granules contain different chemicals depending on the type of cell.

Monocytes (non)

• which comprise approximately 7 percent of all leukocytes. Monocytes eventually become macrophages.

• Lymphocytes ( specific)comprise 30 to 40 percent of all leukocytes.

• Lymphocytes travel through the blood searching for foreign cells.

• There are two kinds – • B lymphocytes (B cells) that mature in bone

marrow and use antibodies to target bacteria.

• T lymphocytes (T cells) that mature in the thymus and actually do the fighting.

B cells (specific)• B cells work by using tiny antibodies. There are

thousands of different B cells in the blood at any time, each armed with antibodies against a particular germ. But there are only a few of each until there is contact with any particular germ.

• Then, B cells multiply dramatically very quickly and release large amounts of the right antibodies.

The process works like this:

• when a germ bumps into a B cell, the B cell multiplies, forming versions of itself called "plasma" cells.

• Plasma cells make antibodies to attack the germ. The antibodies lock on to the target germ to make it easy for phagocytes to eat. Some of the B cells continue multiplying after the germ has been destroyed, so that if the germ returns, there are antibodies ready for it.

Antibodies

• They attach to viral particles so that the cell can recognize that they are foreign to the body and attack them!

T cells (specific)• T cells work a little differently. Because

many germs, such as viruses or parasites, hide inside cells, it is the job of the T cells to identify and destroy these cells. There are two kind of T cells: "killer" cells and "helper" cells. Helper cells are the ones that identify the invaded cells and send out the alarm. Killers are the ones that move in and destroy them.

• This happens because an invaded cell gives itself away with abnormal proteins on its surface. When helper cells encounter abnormal proteins, the send out chemicals called lymphokines that tell killer cells to multiply. The killer cells lock on to the abnormal cell and destroy it. And, like B cells, some killer cells stay around, ready to attack any more abnormal cells they meet. The “memory” part of the immune system!

• Describe B and T cell response

• B cells make antibodies in response to antigens. B cells activate the immune system and help identify the foreign invader by marking them with the antibodies.

• T-cells make cytotoxic t helper cells to destroy and release cytokines and send out the alarm!. T cells identify and kill the invading cells inside other cells

• 19. T cells also display only one receptor on the surface of the cell. Compare and contrast a T cell with a B cell.

• Lymphocytes in the thymus mature into T cells, while lymphocytes in the bone marrow mature Into B cells.

• The T and B cells, however function differently.Whereas the antigen receptors of B cells bind to epitopes of intact antigens circulating in body fluids, those of T cells bind only to fragments of antigens that are displayed on the surface of host cells.

• 23. List four major characteristics of the adaptive immune system.

• 1. There is an immense diversity of lymphocytes and receptors, enabling the immune system to detect pathogens never before encountered.

• 2. Self-tolerance• 3. Cell proliferation triggered by activation greatly

increases the number of B and T cells specific for an antigen.

• 4. Immunological memory allows for a more rapid response to an antigen previously encountered.

• Diversity comes from the way DNA is transcribed and then RNA is edited…

• Variable and constant regions make for almost unlimited types of antibodies.

DNA ofundifferentiatedB cell

DNA ofdifferentiatedB cell

Recombination deletes DNA betweenrandomly selected V segment and J segment

Functional gene

Transcription

RNA processing

Translation

pre-mRNA

mRNA

Light-chain polypeptideAntigen receptor

B cellVariableregion

Constantregion

2

3

4

1

Poly-A tailCap V39 J5

J5V39

V37 V38 V39

V37 V38 V39 V40

J5

J5J4J3J2J1

Intron

Intron

V C

C

C

C

C

C

C C

C

VVV

V

Intron

Figure 43.13

• 40. Using examples, explain the difference between active and passive immunity.

• Active immunity refers to long-term defenses that arise when a pathogen infects the body, activating B cells and T cells and the resulting memory cells specific to the pathogen. Passive immunity refers to short-term immunity conferred by the transfer of antibodies, as occurs in the transfer of maternal antibodies to a fetus or nursing infant.

• Differentiate between passive and active immunity.

• Passive: no work required! The person is given or gets immunity by another source. Babies nursing or some anti-venom drugs work this way.

• Active: the immune system has to work to develop immunity. The person is exposed to the disease or is given a vaccination

Blood cell development

Chronic Lymphocytic Leukemia

• In CLL, too many blood stem cells develop into abnormal lymphocytes and do not become healthy white blood cells. The abnormal lymphocytes may also be called leukemic cells. The abnormal cells are not able to fight infection very well and the number of lymphocytes increases in the blood and bone marrow leaving less room for healthy white blood cells, red blood cells, and platelets. This may result in infection, anemia, and easy bleeding.

Risk Factors• Anything that increases your risk of getting a

disease is called a risk factor. Having a risk factor does not mean that you will get cancer; not having risk factors doesn’t mean that you will not get cancer.

• People who think they may be at risk for any disease should discuss it with their doctor.

Risk factors for CLL include the following:• Being middle-aged or older, male, or white. • A family history of CLL or cancer of the lymph

system. • Having relatives who are Russian Jews or Eastern

European Jews.

• 46. What are allergies?

• Allergies are exaggerated (hypersensitive) responses to certain antigens called allergens.

• 48. Explain what happens if a person experiences anaphylactic shock.

• Anaphylactic shock is a whole-body, life-threatening reaction that can occur within seconds of exposure to an allergen. Anaphylactic shock develops when widespread release of mast cell contents triggers abrupt dilation of peripheral blood vessels, causing a precipitous drop in blood pressure, as well as constriction of bronchioles

vaccine• A preparation of a weakened or killed pathogen, such as a bacterium or virus, or of a portion of the pathogen's structure that upon administration stimulates antibody production against the pathogen but is incapable of causing severe infection

A vaccine is

• A small dose of the weakened virus is given to the patient so that antibodies can form.

• They stimulate the immune system to produce cells which remember the pathogen.

Vaccines

• DPT, MMR, Varicella, HIB, HBV are examples of common vaccinations.

• Killed or weakened pathogens are given to the person to stimulate the immune system so that when faced with the “real” pathogen, the body already has a line of defense!

• 17. How does a vaccination trigger active immunity?

• It provides a weak or killed version of the pathogen so the body can develop antibodies to it. (active immunity)

• That way when faced with the pathogen again, the body already has a defense set up! memory cells and killer cells will be able to destroy it before it causes a disease.

Recombinant DNA

• Has helped us find molecular caused to diseases and better ways to treat and prevent them.

DNA technology• Is looking at ways to help “cure” genetic

diseases by inserting working copies of genes into people with defective genes.

• Examples of genetic diseases include:

• Cystic fibrosis

• Downs syndrome (trisomy 21)

• Juvenile diabetes

• Huntington's, sickle cell etc

• Endemic: found in small amounts in populations

• Epidemic: large out breaks afflicting many people.

• Pandemic: If the epidemic is wide spread over large areas of the country or world!

• SC.912.L.14.6 Explain the significance of genetic factors, environmental factors, and pathogenic agents to health from the

perspectives of both individual and public health

• HE 912.C.1.4 Analyze how heredity and family history can impact personal health

• Family history of health problems may cause a greater chance of or predisposition for certain diseases.

• Genetic factors or genetically passed on diseases

• Coronary artery disease is an example of one such disease with environmental and genetic risk factors. Breast cancer is another.

• Albinism, sickle cell, Huntington and hemophilia are other genetic disorders.

•    

What is public health?• "a state of complete physical, mental and

social well-being and not merely the absence of disease or infirmity", as defined by the United Nations' World Health Organization.[2]

• Public health incorporates the interdisciplinary approaches of epidemiology, biostatistics and health services. Environmental health, community health, behavioral health, health economics, public policy and occupational health are other important subfields.

• The environment can contribute to diseases when sanitation is an issue, second hand smoke, carcinogens are present and many other examples!

• Government can control sanitation of water and help prevent pathogens from being transmitted!

• They can also educate the public!

• Public awareness can limit exposure and lessen the degree of illness!

• Education of how disease spreads can less outbreaks!

• HE 912.C.1.8 Analyze strategies for prevention, detection and treatment of communicable and chronic diseases.

• How can you prevent a disease from spreading?

• How do you determine if a disease is present in an area?

• What can be done to treat a large group of people with a disease?

• Are there risk factors?

• SC.912.L.16.10 Evaluate the impact of biotechnology on the individual, society and the environment including medical and ethical issues.

•  

• Genetic engineering of crops? Problems to health?

• Genetically engineered drugs/ problems? Advantages?

•  

Concerns of biotechnology!

• Wild plants could crossbreed with engineered crop plants and become "super weeds.“

• Loss of confidentiality could cause discrimination in the workplace.

• Future generations of humans could be affected if reproductive cells are involved in gene therapy.