Unit 10Chapter 39

Immunity from Disease

The Nature of Disease

PathogensDisease producing agents, such as,

bacteria, viruses, protozoans, fungi & other parasites

Infectious diseaseAny disease caused by the presence of

pathogens in the body

The Nature of Disease

Koch’s postulates of 1884 (a procedure to establish the cause of a disease)

1) A pathogen must be found in the body of a sick organism

2) The pathogen must be isolated & grown in the lab to produce a culture

3) When the cultured pathogen is placed in a new host, it should cause the same disease

4) The pathogen should be isolated from the new host and shown to be the original pathogen

The Nature of Disease

Endemic diseaseDisease that are constantly present in a

population (ex: common cold)EpidemicWhen many people in a given area are

affected with the same disease at about the same time (ex: influenza)

The Nature of Disease

Antibiotics Substances produced by microorganisms that,

in small amounts, will kill or inhibit the growth & reproduction of other microorganisms

Ex: Penicillin, an antibiotic produced by a fungus, has been in use for over 50 years; many microorganisms are now resistant to penicillin

The Immune System

Innate ImmunityYour body’s own built-in defense

system First (& best) line of defense:

– Unbroken skin– Body secretions, such as

mucus, tears, sweat, & saliva

The Immune System

Second line of defense is inflammatory response:

Fever= increased body temperature slows or stops the growth of pathogens

Phagocytes = white blood cells, such as macrophages, that destroy pathogens

Interferon = proteins that protect cells from viruses

The Immune System

Third line of defense is cellular immunity: Lymphocytes are types of white blood cells

that defend the body against foreign substances

T cells are lymphocytes that defend against abnormal cells & pathogens inside livings cells

B cells are lymphocytes that provide immunity against antigens & pathogens in the body fluids

The Immune System

Lymph Tissue fluid (to bathe, nourish cells) after it

enters the lymph vessels that will return it to the blood

Lymph nodes Glands that filter pathogens from the lymph

before it returns to the bloodstream

The Immune System

Acquired Immunity Defending against a specific pathogen by gradually

building up a resistance to it.

Passive = acquired naturally when antibodies are transferred from mother to unborn child through the placenta

Active = acquired artificially when induced by vaccines

Nonspecific defense

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Cellular immunity

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