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Human Disease and Immune System

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Methods of Transmission/Spread of Infectious Disease ... Athlete's foot, ringworm. Not limited to skin; can be internal. Ex. San Joaquin Valley Fever ... – PowerPoint PPT presentation

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Title: Human Disease and Immune System


1
Human Disease and Immune System
2
Disease
  • Any change, other than injury, that interferes
    with the normal functioning of the body

3
Infectious Disease
  • Produced by pathogens
  • pathogens disease causing microorganisms
  • Results when pathogen begins to injure cells and
    tissue

4
Infection
  • When a pathogen has successfully invaded the body
  • Not all infections produce disease

5
Methods of Transmission/Spread of Infectious
Disease
  • Direct contact with infected person Airborne
  • Coughing, Sneezing Droplets in air
  • Direct contact with secretions of infected person
  • ex. blood, (blood transfusions, contaminated
    needles, cuts/wounds)
  • ex. Sexual contact
  • Contact with infected animals (ex. ticks,
    mosquito)
  • Contaminated water or food

6
Bacteria
  • Most harmless
  • Infect tissues directly
  • Produces toxins (poisons)
  • Ex. botulism (s.n. Clostridium botulinum)
  • Attacks nervous system often fatal

7
Bacteria cont.
  • Some grow in living cells
  • Ex. Ricketsias
  • Ticks-Rocky Mountain Spotted-Fever
  • Typhus- by lice or fleas

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9
Fungi
  • Molds, mushrooms
  • Most do not cause disease
  • Fungal infections
  • Many caused by dermophytes
  • Ex. Athletes foot, ringworm
  • Not limited to skin can be internal
  • Ex. San Joaquin Valley Fever

10
Protozoan
  • 30 different species can cause human disease
  • Many in tropical regions
  • Ex. Malaria (Plasmodium)
  • Lives in bloodstream
  • Spread by mosquitoes

11
Protozoan cont.
  • Ex. Amebic dysentery (Entamoeba histolytica)
  • Affects intestineabdominal pain and fever
  • Contaminated water

12
Protozoan cont.
  • Ex. African Sleeping sickness (Trypanosoma)
  • Spread by tsetse fly
  • Tropics in Africa
  • Inflammation of nervous system
  • Usually fatal

13
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15
Virus
  • Non-cellular particles invade living cells
  • Have genetic info---RNA or DNA
  • No lifelike activity until infect living cells

16
Virus
  • Attaches to cell structure
  • Inserts genetic material
  • May lie dormant or act immediately

17
Virus
  • Examples
  • HIV causes AIDS (Acquired Immune Deficiency
    Syndrome
  • Poliomyelitis causes Polio
  • Variola causes Smallpox
  • Measles

18
Virus
19
Virus
20
Kochs Postulates
Suspected pathogen
No pathogen
Suspected pathogen
The pathogen should always be found in the body
of a sick organism and should not be found in a
healthy one.
The pathogen must be isolated and grown in the
laboratory in a pure culture.
Suspected pathogen grown in pure culture.
Dead mouse
Dead mouse
Healthy mouse
Injection of organisms from pure culture
Pathogen
When purified pathogens are placed in a new host,
they should cause the same disease that infected
the host.
The very same pathogen should be reisolated from
the second host. And it should be the same as
the original pathogen.
Dead mouse
Healthy mouse
21
Immune Response
  • The bodys reaction against a foreign substance
  • Nonspecific Defense
  • Specific Defense

22
Nonspecific Defense
  • Acts against all disease-causing organisms in the
    same way regardless of the biological nature of
    the organism

23
Nonspecific Defense cont.
  • 1st line of defense
  • Skin prevents entry of pathogen
  • Mucustraps pathogens
  • Sweat and oil produce acidic environment that
    kills bacteria
  • Secretions (i.e. mucus, sweat, saliva,
    tears)-contain enzymes that kill bacteria

24
Nonspecific Defense cont.
  • 2nd line of defense Inflammatory response
  • White blood cells enter infected area
  • Phagocytesengulf and destroy bacteria
  • Macrophages large engulf 100s of bacteria
  • Neutrophils smaller engulf small s of bacteria

25
 The Inflammatory Response
Wound
Skin
Phagocytes move into the area and engulf the
bacteria and cell debris
Bacteria enter the wound
Capillary
26
Specific Defense.
  • Immune response
  • Antigen Substance that triggers an immune
    response
  • Humoral Immunity
  • Cell-Mediated Immunity
  • Permanent Immunity

27
Primary and SecondaryImmune Responses
Interval between exposures
First exposure
Second exposure
Antibody Concentration
Time
28
 Structure of an Antibody
Antigen-binding sites
Antigen
Antibody
29
Humoral Immunity
  • Immunity against pathogens in body fluids (blood
    lymph)
  • Antibody basic functional unit of humoral immune
    response

30
 Humoral Immunity
Bacterial antigens also stimulate B cells
Bacteria With Antigens on Surface
B cell
Helper T cell assists the activated B cell to
develop into an antibody-producing plasma cell
Active B cells proliferate to produce clones of
memory cells
A large phagocyte called a macrophage engulfs a
bacterium
Plasma cell produces large amounts of antibody
proteins, released intothe bloodstream
T cell binds to activated macrophage
T cell, activated by macrophage, becomes a helper
T cell
T cell
Macrophage
Antigens are displayed on surface of macrofage
after digestion of bacterium
Circulating antibodies bind to bacterial
antigens, helping other immune cells to identify
and destroy bacteria
31
Cell-MediatedImmune Response
Helper T cell activates killer T cells and B
cells
Macrophage
T cell binds to activated macrophage
Helper T Cell
Killer T Cell
T Cell
T cell, activated by macrophage, becomes a helper
T cell
Antigens are displayed on surface of macrophage
Infected Cell
Killer T cells bind to infected cells, disrupting
their cell membranes and destroying them
32
Permanent Immunity
  • Once a body has been exposed to a pathogen,
    memory B T cells remain capable of producing
    specific antibodies to that pathogen.

33
Active Immunity
  • Edward Jenner (cowpox, smallpox)
  • Vaccination (Vacca cow)
  • Injection of weakened or mild form of pathogen
  • Produces active immunity
  • Body has ability to initiate immediate active
    immune response
  • Body makes its own antibodies

34
Passive Immunity
  • Last short time
  • Antibodies produced by other animals injected
    into the bloodstream
  • Antibodies produce passive immunity
  • Ex. Travelers, Maternal immunity

35
Immune System Disorders
  • Allergies
  • Autoimmune Disease

36
What Are Allergies?
  • Ahhhhchoo! Do you or someone you know have
    allergies? As you know, the immune system
    protects the body against invading pathogens.
    Sometimes, however, the immune system can make a
    mistake. Allergies occur when the immune system
    overreacts to an antigen, a substance that
    triggers an immune response.

37
Allergies
  • Overreaction of immune system
  • Antigens bind to mast cells
  • Mast cells release histamines
  • Histamines increase blood flow fluids
  • Take antihistamines to counteract allergies

38
Autoimmune
  • Immune system makes a mistake and attacks the
    bodys own cells.
  • Ex Streptococcusif not treated can cause
    Rheumatic fever (atttacks/scars lining of heart)
  • Ex. Juvenile-onset diabetes (attacks insulin
    producing cells of pancreas)

39
Autoimmune cont.
  • Multiple sclerosis (MS)
  • Destruction of myelin sheath surrounding nerve
    fibers
  • AIDS (Acquired Immune Deficiency Syndrome)
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