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Immunity

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Immunity Defenses Against Disease Immunity The ability of the body to resist disease. First studied by Edward Jenner in 1776. He found that he could use fluid from a ... – PowerPoint PPT presentation

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Title: Immunity


1
Immunity
2
Defenses Against Disease
Lymph nodes makes lymphocytes.
White blood cells engulf microorganisms.
Cilia in respiratory tract sweep away debris.
Spleen filters out bacteria.
Stomach acid kills bacteria.
Skin acts as a barrier.
3
Immunity
  • The ability of the body to resist disease.
  • First studied by Edward Jenner in 1776.
  • He found that he could use fluid from a cowpox
    sore to vaccinate against smallpox (often fatal).

4
How Immunity Works
  • The body is able to tell the difference between
    self (its own cells and molecules) and
    nonself (foreign cells and molecules).

5
How Immunity Works
  • The reaction of the body to nonself cells is
    called the immune response.
  • This involves destroying or neutralizing foreign
    cells or molecules with white blood cells and
    lymphatic tissue.

6
The Immune Response
  • Antigens cause the immune response to happen.
  • Most antigens are proteins, but some are
    carbohydrates and nucleic acids.
  • Most microorganisms and toxins contain antigens.

7
The Immune Response
  • Recognition and destruction of foreign antigens
    is the job of the lymphocytes.
  • Lymphocytes are made in the bone marrow of the
    embryo and are stored in lymphoid tissue.

8
Two Types of Lymphocytes (B T)
  • Each lymphocyte has receptors for only one
    antigen.
  • When the receptors recognize the antigen, the
    lymphocytes become activated.

9
Activation of B Lymphocytes (BLs)
  • When BLs are activated, they enlarge and divide
    repeatedly to form two different cell types
  • 1. Plasma Cells
  • 2. Memory Cells

10
1. Plasma Cells
  • Plasma cells secrete antibodies, which are
    proteins that react specifically with antigens
    and inactivate them.
  • Antibodies have active sites that fit a
    compatible site on a certain antigen.

11
Antigen-Antibody Reactions
  • There are many different types of antibodies and
    they inactivate antigens in five different ways.

antigens
antibodies
12
Antigen-Antibody Reactions
  • 1. Agglutination Antigens are clumped together
    and thus inactivated.
  • 2. Precipitation Antibodies form a complex with
    the antigens, and the complex settles out.

13
Antigen-Antibody Reactions
  • 3. Neutralization Antibodies combine with
    antigens, inactivating the toxic site of the
    antigen molecule.

14
Antigen-Antibody Reactions
  • 4. Lysis Antibodies cause the cell membranes of
    the antigenic microorganisms to burst.

15
Antigen-Antibody Reactions
  • 5. Complement System The complement system is a
    group of enzymes in the plasma. The
    antigen-antibody complex activates these
    enzymes, which attack the antigenic material.

16
2. Memory Cells
  • The memory cells stay in the lymphoid tissue.
  • If the same antigen enters the body, the memory
    cells will immediately produce antibodies against
    it.

17
Activation of T Lymphocytes (TLs)
  • When TLs contact an antigen, they divide rapidly
    and make more TLS.Some stay in the lymphoid
    tissue as memory cells.
  • Other TLs pass into the circulatory system and
    body tissues, where they combine with the
    antigens and destroy them.

18
How Lymphocytes Make Antibodies
  • Click here for animation.

19
Types of Immunity
  • Three main types of immunity
  • 1. Inborn Immunity
  • 2. Acquired Immunity
  • 3. Passive Immunity

20
1. Inborn Immunity
  • Does not involve antibodies.
  • Present in all humans from birth.
  • Prevents humans from becoming infected with
    certain types of bacteria and viruses.
  • Ex. Feline leukemia affects cats not humans.

21
2. Acquired Immunity
  • Two ways to get it
  • 1. Contracting a disease-Ex. Chicken pox. Memory
    cells will,stay in the body and produce
    antibodies.
  • 2. Vaccination-Vaccine serves to stimulate the
    production of specific antibodies to certain
    antigens.

22
3. Passive Immunity
  • Does not last long (about one month).
  • Body destroys the borrowed antibodies.
  • Fast acting.
  • Found in babies who get antibodies via mothers
    milk.
  • Helps protect child for a few months.
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