Chapter 7: Cellular response in defence.

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Chapter 7 Cellular response in defence.

• Higher Human

Unit 1 Cell Function and Inheritance
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Learning Intentions

• You 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.

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Previous 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?

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THE IMMUNE SYSTEM

• We all get sick sometimes...but then we get
  better.
• What happens when we get sick?
• Why do we get better?

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Cellular Defence

• We are constantly surrounded by an almost
  infinite number of micro-organisms on surfaces,
  airborne, inside us, on our skin, in food,
  clothing. Everywhere.

VIRUSES
FUNGI
BACTERIA
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Random 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 (51030) bacteria on
  Earth, forming much of the world's biomass
• You 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.
  

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Random facts cont

• One 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 10-100 million
  different species of bacteria.

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back 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.

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So 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 be
• INNATE (non-specific) or
• ACQUIRED (specific)

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IMMUNITY
INNATE (nonspecific)
ACQUIRED (Specific)
Skin, HCl, cilia, mucus etc.
ACTIVE
PASSIVE
ARTIFICIAL
NATURAL
ARTIFICIAL
NATURAL
Antibodies 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, flu
Antibodies pre-made by other organism such as a
horse. E.g. tetanus
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INNATE 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 barriers
• Cellular response
• phagocytosis
• inflammatory reaction
• NK (natural killer) and mast cells
• Soluble factors

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INNATE 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.

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INNATE IMMUNITY The barriers

• Physical
• skin
• hair
• mucous

• Chemical
• sweat
• tears
• saliva
• stomach acid
• urine

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Inflammatory response
INNATE IMMUNITY Cellular response

• chemical and cell response to injury or
  localized infection
• eliminates the source of infection
• promotes wound healing

Step 1. Circulation to the site increases ?
tissue warm, red and swollen Step 2. WBCs leak
into tissues ? phagocytes engulf and destroy
bacteria
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Inflammatory response (contd)
INNATE IMMUNITY Cellular response
Fevers have both positive and negative effects on
infection and bodily functions

• POSITIVE
• indicate a reaction to infection
• stimulate phagocytosis
• slow bacterial growth
• increases body temperature beyond the tolerance
  of some bacteria
• decreases blood iron levels

• NEGATIVE
• extreme heat ? enzyme denaturation and
  interruption of normal biochemical reactions
• gt 39 C (103F) is dangerous
• gt 41C (105F) could be fatal and requires
  medical attention

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Phagocytosis 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
• Monocytes
• Macrophages engulf pathogens and dead cell
  remains.
• Neutrophils release chemicals that kill nearby
  bacteria.

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The reason for PUS
During 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 PUS
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Phagocyte migration
CELLS 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.
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Macrophages

• 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.

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Macrophage and E. coli
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Macrophage 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 albicans
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Neutrophils

• WBCs are phagocytic, like macrophages
• neutrophils also release toxic chemicals that
  destroy everything in the area, including the
  neutrophils themselves

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Neutrophil 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.
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Neutrophil killing yeast
NEUTROPHIL
?
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.
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Phagocytosis 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.

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Surround 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.

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The stages of attack.
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IMMUNITY
INNATE (nonspecific)
ACQUIRED (Specific)
Skin, HCl, cilia, mucus etc.
ACTIVE
PASSIVE
ARTIFICIAL
NATURAL
ARTIFICIAL
NATURAL
Antibodies 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, flu
Antibodies pre-made by other organism such as a
horse. E.g. tetanus
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Remember immunity can be

• Immunity can be
• INNATE (non-specific) we have just done this so,
  ........... On to
• ACQUIRED (specific) IMMUNITY

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• Your moms 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 cant 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.

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Acquired 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.

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Antigens

• An 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 WBCs to
  produce special protein molecules called
  antibodies

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Antibodies

• 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 1000s of different types of
  lymphocytes each capable of responding to one
  specific antigen and producing the appropriate
  antibody.

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IMMUNITY
INNATE (nonspecific)
ACQUIRED (Specific)
Skin, HCl, cilia, mucus etc.
ACTIVE
PASSIVE
ARTIFICIAL
NATURAL
ARTIFICIAL
NATURAL
Antibodies 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, flu
Antibodies pre-made by other organism such as a
horse. E.g. tetanus
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Natural 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 thymus
• B-lymphocytes (B-cells) from other places.

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Acquired 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.

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• The 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.

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T-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
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Acquired immunity Natural - T lymphocytes

• The second type of Lymphocytes are T-Lymphocytes
• AKA killer T cells.

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T-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

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Immunological memoryPrimary 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.

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Immunological 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-cells
• HERE THE PERSON HAS AQUIRED IMMUNITY IN A NATURAL
  WAY!

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Immunological memory -memory cells
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Essay Question 2002

• Give an account of immunity under the following
  headings.
• B-lymphocytes and T-Lymphocytes (7)
• Macrophages (3)

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IMMUNITY
INNATE (nonspecific)
ACQUIRED (Specific)
Skin, HCl, cilia, mucus etc.
ACTIVE
PASSIVE
ARTIFICIAL
NATURAL
ARTIFICIAL
NATURAL
Antibodies 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, flu
Antibodies pre-made by other organism such as a
horse. E.g. tetanus
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NATURAL PASSIVE IMMUNITY
Natural Antibodies from mother passes into
babys blood via breast milk or across the
placenta. This is temporary until babys 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.

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Essay Question 2009

• 2. A. Describe how immunity is naturally
  acquired. (10).

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IMMUNITY
INNATE (nonspecific)
ACQUIRED (Specific)
Skin, HCl, cilia, mucus etc.
ACTIVE
PASSIVE
ARTIFICIAL
NATURAL
ARTIFICIAL
NATURAL
Antibodies 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, flu
Antibodies pre-made by other organism such as a
horse. E.g. tetanus
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Artificial 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
  pathogen
• Polio vaccine is a weakened form of the vaccine.
• Cholera vaccine is a dead microbe whose antigens
  are unaltered.

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Vaccines cont

• No 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!

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IMMUNITY
INNATE (nonspecific)
ACQUIRED (Specific)
Skin, HCl, cilia, mucus etc.
ACTIVE
PASSIVE
ARTIFICIAL
NATURAL
ARTIFICIAL
NATURAL
Antibodies 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, flu
Antibodies pre-made by other organism such as a
horse. E.g. tetanus
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Acquired 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.

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Essay Question 2001

• Give an account of immunisation under the
  following headings.
• Artificial active immunity. (6)
• Artificial passive immunity (2)
• The impact of vaccination on childhood diseases.
  (2)

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TASK Testing you knowledge!

• Complete Torrance Pg 56 Questions 1-3

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CO-OPERATIVE TASK

• Social goal Equal participation
• Academic goal Describe what is meant by active
  immunity and passive immunity and give natural
  and artificial examples.

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TASK Essay question

• Give an account of specific immunity (10)

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TASK Essay question, on Scholar

• Give an account of the role of lymphocytes in the
  immune system.(10)

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Expected Answer

• B-lymphocytes (4 marks)
• B-lymphocytes mature in the bone marrow
• They produce specific antibodies
• to foreign (or non-self) antigens
• The 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 body
• The memory cells cause a faster/stronger
  secondary immune response (on subsequent exposure
  to the pathogen)
• T-lymphocytes (4 marks)
• T-lymphocytes mature in the thymus
• The antigens on infected cells are changed and
  recognised as foreign antigens by T-lymphocytes
• The T-lymphocytes destroy the infected cells
  directly
• This is known as the cell-mediated response
• (After the initial response) memory cells remain
  in the body
• The 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.

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What makes us sick?

• Enemies in the environment in the form of
  microbes and chemicals are constantly attacking
  our bodies, disrupting homeostasis
• Smetimes immune system homeostasis is disrupted
  on its own

?
?
it may over-react to antigens such as with
allergies
it may react to self proteins as with autoimmune
disease
?
it may under-react as with human
immunodeficiency virus infection (HIV)
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Allergies

• Allergies 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

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• There 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.

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Self and Non-self

• Membranes 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.
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Non-self

• Cells 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.

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ABO Blood Grouping

• Blood is made from
• PLASMA (liquid part, clear)
• RBCs (carry oxygen, makes blood red, have no
  nucleus but do have a membrane)
• WBCs (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.

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Blood grouping

• RBC membranes, like all other cells, have a
  protein signature (antigens).
• There are 4 main blood groups

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Blood 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 RBCs
(as they have B antigens).
The patients anti-B
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The patient recognises the donors B antigens as
non-self.

• Antibodies in the plasma will attack the RBCs
  (as they have B antigens).
• This results in the blood clumping/thickening
  (agglutination) therefore clogging up blood
  vessels.
• AGGLUTINATON
• of the blood

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So when are groups compatible
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11
3
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Tissue Rejection
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Tissue Rejection cont

• 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.

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Tissue 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.

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Autoimmunity
AUTOIMMUNITY Why does the immune system attack
the body that its 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 its
  own cells.
• Examples of autoimmune diseases
• Rheumatoid Arthritis
• IS attacks cartilage tissue between joints. It
  is eventually replaced, but by fibrous tissue,
  making the joint immovable.
• Multiple Sclerosis
• Nerve cells are attacked leading to poor
  transmission of nerve impulses therefore various
  disabilities.

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TASK Testing you knowledge!

• Complete Torrance Pg 59 Questions 1-4

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WHAT CAN YOU DO TO HELP YOUR IMMUNE SYTSEM?
Exercise and stress

• Exercise has been shown to boost the immune
  response
• moderate exercise increases the immune response
  in all age groups
• intensive exercise can stress the immune system
• Lack of sleep and exhaustion decrease immune
  function
• Psychological stress has also been found to
  decrease immune function

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Diet

• A well-balanced diet is essential for good immune
  system health
• fats are very important in the production of
  WBCs, cytokines and natural killer cells
• selenium, zinc, and copper are required in small
  amounts, which you get if you eat a balanced diet
• vitamin E has been shown to boost antibody
  production in the elderly
• vitamin B6 aids in antibody synthesis
• But mega-dosing can be harmful, too!

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Environment
Exposure to certain things in their environment
may activate the immune systems of some people

• Chemicals
• dioxin
• pesticides
• solvents
• Sunlight
• Medication

• Viruses
• Bacteria
• Food

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Acquired immunodeficiency syndrome (AIDS)

• First identified in 1981 - 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 virus

Worldwide HIV infection, 1999
HIV virus particle