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Immune System

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Immune System Pre-AP Biology Chapter 40-2 Immune System Overview Function: fight infection through the production of [specialized] cells that inactivate foreign ... – PowerPoint PPT presentation

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Title: Immune System


1
Immune System
  • Pre-AP Biology
  • Chapter 40-2

2
Immune System Overview
  • Function fight infection through the production
    of specialized cells that inactivate foreign
    substances or cells
  • It is main defense against pathogens
  • Recognizes, attacks, destroys, and remembers
    each type of pathogen that enters the body
  • 2 general categories
  • Nonspecific defenses (fortress walls of the body)
  • Specific defenses (security guards of the body)

3
Nonspecific Defenses
  • First line of defense skin
  • Most important nonspecific defense!
  • Very few pathogens can penetrate the skin
  • Must have an opening a cut, scratch, mouth,
    nose
  • Mucus, saliva, and tears have lysozyme enzyme
    that breaks down bacterias cell wall
  • Oil and sweat glands produce acidic environment
  • Mucus and cilia in nose and throat trap and push
    pathogens away from lungs
  • Acid and enzymes destroy bacteria that make it to
    your stomach

4
Nonspecific Defenses
  • Second line of defense inflammatory response
  • Reaction to tissue damage caused by
    injury/infection
  • When pathogens are detected
  • White blood cells flood area through blood
    vessels near wound
  • Many WBC are phagocytes engulf and destroy
  • Releases chemicals that increase core body
    temperature (fever)
  • Many pathogens only survive in narrow temp. range
  • Increased temp also increases heart rate more
    WBC

5
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6
Nonspecific Defense to Viruses
  • Sometimes, virus-infected cells produce a group
    of proteins that help other cells resist
    infection Interferons
  • Named this because they interfere with growth
    of the virus
  • Slows the progress of infection and gives
    specific defense system time to respond

7
Specific Defenses
  • Called immune response
  • Triggered by antigens
  • 2 types of lymphocytes
  • B lymphocytes (B cells) work in body fluids
  • Humoral immunity
  • T lymphocytes (T cells) work in living cells
  • Cell-mediated immunity

8
Humoral Immunity
  • B cells detect pathogen and multiply rapidly
  • Produces large numbers of plasma cells and memory
    B cells
  • Plasma cells release antibodies (proteins that
    recognize and bind to antigens recall blood
    types!)
  • Antibodies carried in the blood stream to attack
  • Memory B cells remain capable of producing
    antibodies specific to that pathogen after
    exposure

9
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10
Antibody Structure
  • Antibody is shaped like a Y and has two
    identical antigen binding sites
  • Differences in amino acids affect shape of
    binding sites
  • Shape of binding site is how antibody recognizes
    antigen
  • Healthy adult can produce about 100 million
    different types of antibodies!

11
Cell-Mediated Immunity
  • Primary defense against own cells when cancerous
    or infected
  • Also important for fighting fungi and protists
  • Process T cells divide and differentiate into
  • Killer T cells destroy bacteria, fungi,
    protozoan or foreign tissue with the antigen
  • Helper T cells produce memory T cells
  • Suppressor T cells shut down killer T cells
    after pathogenic cells brought under control
  • Memory T cells cause response if same antigen
    enters again

12
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13
Transplants
  • Killer T cells make organ transplants difficult
  • Recognize new organ as foreign and attack it
  • Called rejection
  • To prevent rejection, donor should have cell
    markers nearly identical to recipient and
  • Recipient usually takes drugs for the rest of
    their life to suppress cell-mediated immune
    response.

14
Acquired Immunity
  • Remember Jenners smallpox??
  • Cowpox infection to create immunity to smallpox
  • Can be active or passive

15
Active vs. Passive Immunity
  • Active
  • Passive
  • Type of immunity produced by reaction to a
    vaccine
  • Vaccination injection of weakened or mild form
    of pathogen
  • Stimulate immune system to create plasma cells
  • Plasma cells are ready to make specific
    antibodies
  • Appears AFTER exposure
  • Can be natural or deliberate
  • Antibodies produced by other animals injected
    into the bloodstream
  • Lasts for short time body eventually destroys
    them
  • Can be natural or deliberate
  • Natural from mother to fetus or in breastmilk
  • Deliberate vaccine
  • Tropical diseases
  • Rabies
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