Presentation on theme: "Chapter 7: Cellular response in defence."— Presentation transcript:
1Chapter 7: Cellular response in defence. Higher HumanUnit 1: Cell Function and InheritanceChapter 7: Cellular response in defence.06/04/2017Mrs Smith
2Learning IntentionsYou should be able to describe self and non-self antigens as in ABO blood group system.You should be able to explain the production of antibodies and the role of blood cells.Describe phagocytosis and the function of lysosomes.Know the differences between innate, acquired, active and passive immunity.Describe what is meant by auto immunity and what causes allergy in the body.06/04/2017Mrs Smith
3Previous knowledge Every body cell has a membrane There are proteins in and on this membrane (phospholipid bi-layer)What are the 6 functions of these proteins?What is an immune system?
4THE IMMUNE SYSTEM We all get sick sometimes...but then we get better. What happens when we get sick?Why do we get better?Mrs Smith06/04/2017
5Cellular DefenceWe are constantly surrounded by an almost infinite number of micro-organisms – on surfaces, airborne, inside us, on our skin, in food, clothing. Everywhere.VIRUSESBACTERIAFUNGI
6Random facts about bacteria There are typically 40 million bacterial cells in a gram of soil and a million bacterial cells in a millilitre of fresh water; in all, there are approximately five nonillion (5×1030) bacteria on Earth, forming much of the world's biomassYou can fit thousands upon thousands of bacteria on a pinhead.There are approximately ten times as many bacterial cells in the human flora of bacteria as there are human cells in the body, with large numbers of bacteria on the skin and as gut flora.
7Random facts con’tOne survey found 20,000 species of bacteria in a litre of seawater.The number of scientifically recognized species of animals is about 1,250,000 (most are insects). There are almost 300,000 recognized species of plants. There are an estimated million different species of bacteria.
8back to Cellular Defence…. Most micro-organisms are actually harmless, but a few species can cause disease if they enter our bodies and grow to sufficient numbers.We call these microbes pathogens.Of all the species of bacteria, only about 30% are pathogenic. And only a small percentage of that 30% can cause harm to human hosts.
9So what is an immune system? Immunity is the ability of the body to resist infection by a disease causing organism (pathogen) o to overcome the organism if it succeeds in invading and infecting the body.Immunity can beINNATE (non-specific) orACQUIRED (specific)06/04/2017Mrs Smith
10IMMUNITY INNATE (nonspecific) ACQUIRED (Specific) Skin, HCl, cilia, mucus etc.ACTIVEPASSIVEARTIFICIALNATURALNATURALARTIFICIALAntibodies self made after vaccination. E.g. polio, measles.Antibodies pre-made by mother – breastmilk, across placenta. Various antibodies.Antibodies self made after infection. E.g. Chickenpox, fluAntibodies pre-made by other organism such as a horse. E.g. tetanus
11INNATE IMMUNITY: Nonspecific When you were born, you brought with you several mechanisms to prevent illness. This type of immunity is also called nonspecific immunity.Innate immunity consists of:Outer barriersCellular responsephagocytosisinflammatory reactionNK (natural killer) and mast cellsSoluble factorsNK cells are free-roving lymphocytes that identify, bind to, and lyse cancerous and virus-infected cells as part of the non-specific immune response.Lymphocytes are WBCs involved in antibody production and other aspects of the immune response.06/04/2017Mrs Smith
12INNATE IMMUNITY – INBORN and UNCHANGING Nonspecific - the same response works against many pathogens.This type of response is the same no matter how often it is triggered.The types of cells involved are macrophages/neutrophils, natural killer cells, and mast cells.06/04/2017Mrs Smith
13INNATE IMMUNITY – The barriers PhysicalskinhairmucousChemicalsweattearssalivastomach acidurineSweat, tears, saliva, stomach acids and urine contain chemical compounds and/or provide a flushing action that removes pathogens.06/04/2017Mrs Smith
14Inflammatory response INNATE IMMUNITYCellular responseInflammatory responsechemical and cell response to injury or localized infectioneliminates the source of infectionpromotes wound healingStep 1. Circulation to the site increases tissue warm, red and swollenStep 2. WBCs leak into tissues phagocytes engulf and destroy bacteriaThe release of histamine by mast cells is induced by complement.06/04/2017Mrs Smith
15Inflammatory response (cont’d) INNATE IMMUNITYCellular responseInflammatory response (cont’d)Fevers have both positive and negative effects on infection and bodily functionsPOSITIVEindicate a reaction to infectionstimulate phagocytosisslow bacterial growthincreases body temperature beyond the tolerance of some bacteriadecreases blood iron levelsNEGATIVEextreme heat enzyme denaturation and interruption of normal biochemical reactions> 39° C (103°F) is dangerous> 41°C (105°F) could be fatal and requires medical attentionFevers develop because macrophages release the cytokine interleukin–1 (IL-1), a chemical that acts on the hypothalamus, leading to increased body temperature.Bacterial growth requires iron, which is a component of cytochromes and certain non-heme iron proteins and a cofactor for some enzymatic reactions. The increase in temperature that occurs as the result of a fever may lead to bleeding or destruction of RBCs, so that blood iron levels are decreased .The length of a high temperature fever influences mortality due to fever.Prolonged fever influences mortality due to compromised enzyme activity.06/04/2017Mrs Smith
16Phagocytosis – ‘Cell Eating’ When foreign cells such as bacteria and viruses invade the human body the body will respond by attacking them.This is done by white blood cells.Types of phagocytic white blood cells are:MonocytesMacrophages: engulf pathogens and dead cell remains.Neutrophils: release chemicals that kill nearby bacteria.
17The reason for PUSDuring an infection hundreds of white cells migrate to the infected area and engulf the infected bacteria by phagocytosis. Phagocytes and and dead pathogens accumulate causing PUSBacteria release chemicals that act like a generalized announcement of their presence (see next slide, “Phagocyte Migration”). This signal attracts macrophages and neutrophils.06/04/2017Mrs Smith
18Phagocyte migrationCELLS alive!Neutrophils and macrophages recognise chemicals produced by bacteria in a cut or scratch and migrate "toward the smell". Here, neutrophils were placed in a gradient of a chemical that is produced by some bacteria. The cells charge out like a "posse" after the bad guys.Note the ameboid movement of these cells. Seeing the fluidity of the cell membrane enables us to get a better idea of how one cell can engulf another.The above neutrophils were placed in a gradient of fMLP (n formyl methionine- leucine- phenylalanine), a peptide chain produced by some bacteria.06/04/2017Mrs Smith
19Macrophages WBCs that ingest bacteria, viruses, dead cells, dust. Most circulate in the blood, lymph and extracellular fluid.They are attracted to the site of infection by chemicals given off by dying cells.After ingesting a foreign invader, they “wear” pieces of it called antigens on their cell membrane receptors – this tells other types of immune system cells what to look for.06/04/2017Mrs Smith
20Macrophage and E. coli Mrs Smith 06/04/2017 pink = macrophage yellow = bacteria; note rod-like structure of E. coli06/04/2017Mrs Smith
21Macrophage ingesting yeast CELLS alive!This human macrophage, like the neutrophil, is a professional "phagocyte" or eating cell (phago = "eating", cyte = "cell"). Here, it envelops cells of a yeast, Candida albicansDuring an oxidative burst, there is increased oxygen consumption, increased production of hydrogen peroxide and superoxide anion, and increased glucose oxidation. This results in the production of several microbicidal oxidizing agents in the lysosomes (which are the essentially the cell’s garbage disposal system), including superoxide anion, hydroxyl radical, singlet oxygen, and hydrogen peroxide. These will oxidize lipids, such as in the bacterial membranes causing lysis of the bacteria, and will oxidize or cross-link protein destroying their function. The primary enzyme involved in catalyzing the oxidation of foreign materials in the phagocytes is myeloperoxidase, which is contained in the lysosomes. Superoxide dismutase is also involved.06/04/2017Mrs Smith
22WBCs – are phagocytic, like macrophages NeutrophilsWBCs – are phagocytic, like macrophagesneutrophils also release toxic chemicals that destroy everything in the area, including the neutrophils themselves06/04/2017Mrs Smith
23Neutrophil phagocytosing S. pyogenes, the cause of strep throat Human neutrophils are WBCs that arrive quickly at the site of a bacterial infection and whose primary function is to eat and kill bacteria. This neutrophil is ingesting Streptococcus pyogenes.Streptococcus pyogenes, the pathogen that causes strep throat is the yellow, bead-like structure.06/04/2017Mrs Smith
24Neutrophil killing yeast YEAST One way that neutrophils kill is by producing an anti-bacterial compound called “superoxide anion“, a process called oxidative burst. Here, a neutrophil senses, moves toward and ingests a yeast. In the next two panels, oxidation can be seen by using a dye.See teacher’s notes for slide number 13, entitled, “Macrophage Ingesting Yeast”.06/04/2017Mrs Smith
25Phagocytosis – summary A phagocyte detects chemicals released by the bacterium and moves along a concentration gradient (low to high).The phagocyte attaches to the bacterium and engulfs it in a vacuole formed by an infolding cell membrane.The phagocyte has organelles called LYSOSOMES which contains digestive enzymes.06/04/2017Mrs Smith
26Surround and attack! What happens when the bacteria is under attack? White blood cells senses bacteria.White blood cell moves towards bacteria.White blood cell begins to surround bacteria.White blood cell surrounds bacteria.White blood cell kills bacteria.06/04/2017Mrs Smith
28IMMUNITY INNATE (nonspecific) ACQUIRED (Specific) Skin, HCl, cilia, mucus etc.ACTIVEPASSIVEARTIFICIALNATURALNATURALARTIFICIALAntibodies self made after vaccination. E.g. polio, measles.Antibodies pre-made by mother – breastmilk, across placenta. Various antibodies.Antibodies self made after infection. E.g. Chickenpox, fluAntibodies pre-made by other organism such as a horse. E.g. tetanus
29Remember immunity can be: INNATE (non-specific) we have just done this so, On to –ACQUIRED (specific) IMMUNITY
30Your mom’s antibodies were effective for just a short time at birth, but your innate immune system can be activated quickly. It is always your first line of defense during an infection, but it can’t always eliminate the germ.When this happens, your body initiates a focused attack against the specific pathogen that is causing the infection. This attack may lead to long-term protection against that pathogen.This type of immunity is called acquired immunity, the customized second line of defense.This focused attack is your second line of defense, adaptive immunity. It is “customized” to address the presence of a specific pathogen.06/04/2017Mrs Smith
31Acquired immunity: Depends on the action of antibodies to combat antigens Acquired immunity can be split into a further 2 groups:PASSIVE (antibodies made by another organisms i.e. mother, horse)ACTIVE (self production of antibodies)Each with a natural and an artificial aspect to them.
32AntigensAn antigen is a complex molecule such as protein or polysaccharide which is recognised as alien by LYMPHOCYTES (type of wbc).The presence of an antigen stimulates WBC’s to produce special protein molecules called antibodies06/04/2017Mrs Smith
33Antibodies An antibody is a Y-shaped molecule. Each of its arms bears a receptor ‘binding’ site which is specific to a particular antigen.The body has 1000’s of different types of lymphocytes each capable of responding to one specific antigen and producing the appropriate antibody.Antibodies06/04/2017Mrs Smith
34IMMUNITY INNATE (nonspecific) ACQUIRED (Specific) Skin, HCl, cilia, mucus etc.ACTIVEPASSIVEARTIFICIALNATURALNATURALARTIFICIALAntibodies self made after vaccination. E.g. polio, measles.Antibodies pre-made by mother – breastmilk, across placenta. Various antibodies.Antibodies self made after infection. E.g. Chickenpox, fluAntibodies pre-made by other organism such as a horse. E.g. tetanus
35Natural acquired immunity Acquired active natural.Acquired passive natural.Both of these types of immunity require antibodies which are produced by LYMPHOCYTES. These are made in bone marrow.There are two types of lymphocyte.T-lymphocyte (T-cells) from the thymusB-lymphocytes (B-cells) from other places.06/04/2017Mrs Smith
36Acquired immunity : Natural - B lymphocytes The antibodies are made by B-lymphocytes.In the presence of antigens, the B-cells will multiply to produce many antibodies.After the infection some of these B-cells will remain to serve as ‘memory cells’ – ready to respond more quickly if body is exposed to same antigens.
37The production of extra-cellular molecules (antibodies) that deal with specific foreign material is called a HUMORAL RESPONSE.B-lymphocytes are matured in the bone marrow.Leukaemia.
38T-Lymphocytes – Helper T cells These do not kill pathogens directly.These cells patrol the body, and on recognising foreign antigens, the activate killer T cells, B cells and macrophages.Helper T-cell – the judge that identifies germs and orders their destruction
39Acquired immunity : Natural - T lymphocytes The second type of Lymphocytes are T-LymphocytesAKA killer T cells.
40T-Lymphocytes – Killer T cells A killer T cell will attack and destroy body cells (self antigen markers) that signal (by foreign antigens) that they have been invaded by a pathogen.Killer T-cell – Kills germs.The T –cell releases a chemical to destroy the cell and the pathogen in it.This is called a CELL MEDIATED RESPONSE
41Immunological memory Primary and secondary esponse Primary response – after seeing a pathogen for the first time it takes a while before enough antibodies are found in the bloodstream. The infected person usually still gets sick.Secondary response – happens when there is another exposure to the same antigen. Antibody production is rapid, and a higher concentration is reached and maintained for a longer time. Here disease is usually prevented.06/04/2017Mrs Smith
42Immunological memory - memory cells Following the first exposure to the antigen, some B- and T-lymphocytes specific to the antigen remain in the body as memory cells.If exposed to the pathogen again memory cells quickly produce clones of antibody forming B-cells and Killer T-cellsHERE THE PERSON HAS AQUIRED IMMUNITY IN A NATURAL WAY!06/04/2017Mrs Smith
43Immunological memory - memory cells 06/04/2017Mrs Smith
44Essay Question – 2002Give an account of immunity under the following headings.B-lymphocytes and T-Lymphocytes (7)Macrophages (3)06/04/2017Mrs Smith
45IMMUNITY INNATE (nonspecific) ACQUIRED (Specific) Skin, HCl, cilia, mucus etc.ACTIVEPASSIVEARTIFICIALNATURALNATURALARTIFICIALAntibodies self made after vaccination. E.g. polio, measles.Antibodies pre-made by mother – breastmilk, across placenta. Various antibodies.Antibodies self made after infection. E.g. Chickenpox, fluAntibodies pre-made by other organism such as a horse. E.g. tetanus
46NATURAL PASSIVE IMMUNITY Natural – Antibodies from mother passes into baby’s blood via breast milk or across the placenta. This is temporary until baby’s own immune system develops.While your immune system was developing, you were protected antibodies. These antibodies traveled across the placenta from the maternal blood to the fetal blood.Antibodies (Y) are also found in breast milk. The antibodies received through passive immunity last only several weeks.06/04/2017Mrs Smith
47Essay Question – 20092. A. Describe how immunity is naturally acquired. (10).06/04/2017Mrs Smith
48IMMUNITY INNATE (nonspecific) ACQUIRED (Specific) Skin, HCl, cilia, mucus etc.ACTIVEPASSIVEARTIFICIALNATURALNATURALARTIFICIALAntibodies self made after vaccination. E.g. polio, measles.Antibodies pre-made by mother – breastmilk, across placenta. Various antibodies.Antibodies self made after infection. E.g. Chickenpox, fluAntibodies pre-made by other organism such as a horse. E.g. tetanus
49Artificial Aquired immunity.....Active Artificial – Vaccinations. Forced exposure to a “dead” pathogen. This exposure introduces the white blood cells to the antigens so they can produce antibodies. Memory cells remain, allowing a secondary response in needed.Small pox vaccine is a harmless form of the pathogenPolio vaccine is a weakened form of the vaccine.Cholera vaccine is a dead microbe whose antigens are unaltered.
50HERE A PERSON ACQUIRED IMMUNITY BY ARTIFICIAL MEANS! Vaccines con’tNo matter how the vaccine is made or what it contains, its job is to promote production of B and T cells and the formation of antibodies..... Then some will persist as memory cells.HERE A PERSON ACQUIRED IMMUNITY BY ARTIFICIAL MEANS!06/04/2017Mrs Smith
51IMMUNITY INNATE (nonspecific) ACQUIRED (Specific) Skin, HCl, cilia, mucus etc.ACTIVEPASSIVEARTIFICIALNATURALNATURALARTIFICIALAntibodies self made after vaccination. E.g. polio, measles.Antibodies pre-made by mother – breastmilk, across placenta. Various antibodies.Antibodies self made after infection. E.g. Chickenpox, fluAntibodies pre-made by other organism such as a horse. E.g. tetanus
52Acquired immunity -Passive Artificial – antibodies made by a non related organism, usually a different species such as a horse, are injected into bloodstream. This only lasts a few years. E.g. tetanus.
53Essay Question – 2001Give an account of immunisation under the following headings.Artificial active immunity. (6)Artificial passive immunity (2)The impact of vaccination on childhood diseases. (2)06/04/2017Mrs Smith
55CO-OPERATIVE TASK: Social goal: Equal participation Academic goal: Describe what is meant by “active immunity” and “passive immunity” and give natural and artificial examples.
56TASK: Essay questionGive an account of specific immunity (10)
57TASK: Essay question, on Scholar Give an account of the role of lymphocytes in the immune system.(10)
58Expected Answer B-lymphocytes (4 marks) B-lymphocytes mature in the bone marrowThey produce specific antibodiesto foreign (or non-self) antigensThe response of B-lymphocytes is called the humoral response (because the antibodies have their effects away from the B-lymphocytes)(After the initial response) memory cells remain in the bodyThe memory cells cause a faster/stronger secondary immune response (on subsequent exposure to the pathogen)T-lymphocytes (4 marks)T-lymphocytes mature in the thymusThe antigens on infected cells are changed and recognised as foreign antigens by T-lymphocytesThe T-lymphocytes destroy the infected cells directlyThis is known as the cell-mediated responseThe memory cells cause a faster/stronger secondary immune response (on subsequent exposure to the pathogen)Coherence (1 mark)One mark is given if sub-headings are used, or points placed correctly in two groups.Relevance (1 mark)One mark is deducted if macrophages are discussed.Marks for points 5. and 6. of T-lymphocytes cannot be given if they have already been given for points 5. and 6. in B-lymphocytes.06/04/2017Mrs Smith
59What makes us sick?“Enemies” in the environment in the form of microbes and chemicals are constantly attacking our bodies, disrupting homeostasisSmetimes immune system homeostasis is disrupted on its ownit may over-react to antigens such as with allergiesit may react to self proteins as with autoimmune diseaseit may under-react as with human immunodeficiency virus infection (HIV)06/04/2017Mrs Smith
60AllergiesAllergies are basically an overreaction by the immune system to a harmless foreign material.There are several types of allergic reactions: sneezing, wheezing, watering, running nose, itching, coughing, swelling, anaphylaxis
61There are many substances that cause to these over reactions: pollen, dust, dust mites, foods, feather fibres, antibiotics, insect bites…Hayfever is an allergy. The allergen (pollen) causes the B cells to release antibodies which attach to tissues leading to the release of a chemical called histamine.Histamine is responsible for nasal congestion, running nose, constriction of airways etc.
62Self and Non-selfMembranes have a unique combination of surface proteins that are specific to an individual (except identical twins).These proteins are called antigens.The immune system recognises this antigenic “signature” and so knows that these cells belong to ‘self’.
63Non-selfCells that do not have this unique combination of antigens are recognised as “foreign” or non-self and will then be attacked by the immune system.
64ABO Blood Grouping Blood is made from: PLASMA (liquid part, clear)RBC’s (carry oxygen, makes blood red, have no nucleus but do have a membrane)WBC’s (far fewer in number, part of immune system)Human blood is not as simple as just that.There are different types and these variations cannot be overlooked.
65Blood groupingRBC membranes, like all other cells, have a protein signature (antigens).There are 4 main blood groups:06/04/2017Mrs Smith
66Blood transfusions save many lives. However, the blood of the donor has to be compatible with that of the patients.For e.g. If a patient who has blood group A receives blood from a donor with blood group B then…. Antibodies in the plasma will attack the RBC’s (as they have B antigens).The patient’s anti-B
67The patient recognises the donors B antigens as non-self. Antibodies in the plasma will attack the RBC’s (as they have B antigens).This results in the blood clumping/thickening (agglutination) therefore clogging up blood vessels.= AGGLUTINATONof the blood
68So when are groups compatible Antibodies in plasmaAntigens on RBC35%11%3%51%06/04/2017Mrs Smith
70Tissue Rejection con’t When living organs/tissues are transplanted from one organism to another, they are recognised as foreign by the receiver.As a result their immune system will target these cells and destroy the new organ.This attempt to destroy the foreign tissue is called tissue rejection.
71Tissue Rejection can be prevented with IMMUNOSUPPRESORS Transplants can be successful if the donor is genetically very similar to the recipient.IMMUNOSPPRESSOR drugs are then administered. This will inhibit/weaken the patients immune system so it is less able to destroy the new tissue.This, however, puts the patient at a much higher risk of contracting diseases/infections such as pneumonia.
72AUTOIMMUNITY: Why does the immune system attack the body that it’s supposed to protect? Autoimmunity is a malfunction of the immune system where it starts to attack cells with self antigens. In other words the body attacks it’s own cells.Examples of autoimmune diseases:Rheumatoid ArthritisIS attacks cartilage tissue between joints. It is eventually replaced, but by fibrous tissue, making the joint immovable.Multiple SclerosisNerve cells are attacked leading to poor transmission of nerve impulses therefore various disabilities.
74WHAT CAN YOU DO TO HELP YOUR IMMUNE SYTSEM? Exercise and stressExercise has been shown to boost the immune responsemoderate exercise increases the immune response in all age groupsintensive exercise can stress the immune systemLack of sleep and exhaustion decrease immune functionPsychological stress has also been found to decrease immune function06/04/2017Mrs Smith
75Diet A well-balanced diet is essential for good immune system health fats are very important in the production of WBCs, cytokines and natural killer cellsselenium, zinc, and copper are required in small amounts, which you get if you eat a balanced dietvitamin E has been shown to boost antibody production in the elderlyvitamin B6 aids in antibody synthesisBut mega-dosing can be harmful, too!06/04/2017Mrs Smith
76EnvironmentExposure to certain things in their environment may activate the immune systems of some peopleChemicalsdioxinpesticidessolventsSunlightMedicationVirusesBacteriaFood06/04/2017Mrs Smith
77Acquired immunodeficiency syndrome (AIDS) First identified in Caused by the human immunodeficiency virus (HIV) and is spread by contact with body fluids.Infects CD4+ (helper) T cells, which decrease in number.Decreased numbers of CD4+ T cells lead to increased susceptibility to opportunistic infections.Treatments include drugs that inhibit the activity of HIV proteins, thereby preventing production of the virusWorldwide HIV infection, 1999HIV virus particle06/04/2017Mrs Smith