Title: Human Disease and Immune System
1Human Disease and Immune System
2Disease
- Any change, other than injury, that interferes
with the normal functioning of the body
3Infectious Disease
- Produced by pathogens
- pathogens disease causing microorganisms
- Results when pathogen begins to injure cells and
tissue
4Infection
- When a pathogen has successfully invaded the body
- Not all infections produce disease
5Methods 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
6Bacteria
- Most harmless
- Infect tissues directly
- Produces toxins (poisons)
- Ex. botulism (s.n. Clostridium botulinum)
- Attacks nervous system often fatal
7Bacteria cont.
- Some grow in living cells
- Ex. Ricketsias
- Ticks-Rocky Mountain Spotted-Fever
- Typhus- by lice or fleas
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9Fungi
- 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
10Protozoan
- 30 different species can cause human disease
- Many in tropical regions
- Ex. Malaria (Plasmodium)
- Lives in bloodstream
- Spread by mosquitoes
11Protozoan cont.
- Ex. Amebic dysentery (Entamoeba histolytica)
- Affects intestineabdominal pain and fever
- Contaminated water
12Protozoan cont.
- Ex. African Sleeping sickness (Trypanosoma)
- Spread by tsetse fly
- Tropics in Africa
- Inflammation of nervous system
- Usually fatal
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15Virus
- Non-cellular particles invade living cells
- Have genetic info---RNA or DNA
- No lifelike activity until infect living cells
16Virus
- Attaches to cell structure
- Inserts genetic material
- May lie dormant or act immediately
17Virus
- Examples
- HIV causes AIDS (Acquired Immune Deficiency
Syndrome - Poliomyelitis causes Polio
- Variola causes Smallpox
- Measles
18Virus
19Virus
20Kochs 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
21Immune Response
- The bodys reaction against a foreign substance
- Nonspecific Defense
- Specific Defense
22Nonspecific Defense
- Acts against all disease-causing organisms in the
same way regardless of the biological nature of
the organism
23Nonspecific 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
24Nonspecific 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
25Â The Inflammatory Response
Wound
Skin
Phagocytes move into the area and engulf the
bacteria and cell debris
Bacteria enter the wound
Capillary
26Specific Defense.
- Immune response
- Antigen Substance that triggers an immune
response - Humoral Immunity
- Cell-Mediated Immunity
- Permanent Immunity
27Primary and SecondaryImmune Responses
Interval between exposures
First exposure
Second exposure
Antibody Concentration
Time
28Â Structure of an Antibody
Antigen-binding sites
Antigen
Antibody
29Humoral Immunity
- Immunity against pathogens in body fluids (blood
lymph) - Antibody basic functional unit of humoral immune
response
30Â 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
31Cell-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
32Permanent Immunity
- Once a body has been exposed to a pathogen,
memory B T cells remain capable of producing
specific antibodies to that pathogen.
33Active 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
34Passive Immunity
- Last short time
- Antibodies produced by other animals injected
into the bloodstream - Antibodies produce passive immunity
- Ex. Travelers, Maternal immunity
35Immune System Disorders
- Allergies
- Autoimmune Disease
36What 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.
37Allergies
- Overreaction of immune system
- Antigens bind to mast cells
- Mast cells release histamines
- Histamines increase blood flow fluids
- Take antihistamines to counteract allergies
38Autoimmune
- 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)
39Autoimmune cont.
- Multiple sclerosis (MS)
- Destruction of myelin sheath surrounding nerve
fibers - AIDS (Acquired Immune Deficiency Syndrome)