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Immune System
SC.912.L.14.52 Explain the basic functions
of the human immune system, including
specific and nonspecific immune
response, vaccines, and antibiotics
-Students will identify and/or explain the basic
functions of the human immune system, including
specific and nonspecific immune responses.
-Students will describe how the human immune system
responds to vaccines and/or antibiotics.
-Students will explain the significance of genetic
factors, environmental factors, and pathogenic agents
to health from the perspective of both individual and
public health.
Pathogens and Human Illness
Germ theory states that microscopic
particles cause certain diseases.
– proposed by Louis Pasteur
– led to rapid advances in understanding
disease
– Koch’s postulates support the theory.
– Disease-causing agents are called pathogens
There are different types of
pathogens.
Bacteria are single-celled organisms.
– cause illness by destroying cells
– release toxic chemicals
Viruses are genetic material surrounded
by a protein coat.
– force host cells to make more viruses
– very small
Fungi can be multicellular or single-celled.
– take nutrients from host cells
– occur in warm and damp places
Protozoa are single-celled organisms.
– use host cells to complete their life cycles
– take nutrients from host cell
Parasites are multicellular organisms
– grow and feed on a host
– possibly kill the host
Pathogens can enter the body in
different ways.
Pathogens can be transferred by direct or
indirect contact.
Indirect contact does not require touching
an infected individual.
– touching an infected
surface
– breathing in infected
air
Vectors carry a pathogen and transmit it
into healthy cells.
Direct contact requires touching an
infected individual. Includes:
– kissing
– sexual intercourse
– hand shaking
The immune systems consists
of organs, cells, and molecules
that fight infections.
Many body systems protect you
from pathogens.
The immune system is the body system
that fights off infection and pathogens.
Many other tissues and systems help the
immune system.
– Skin is a physical barrier to infection.
– Mucous membranes trap pathogens entering
the body.
– The circulatory system transports immune
cells.
Cells and proteins fight the body’s
infections.
White blood cells attack infections inside the
body.
– Phagocytes engulf and destroy pathogens.
– T cells destroy infected cells.
– B cells produce antibodies.
Three types of proteins fight off invading
pathogens.
– Complement proteins weaken pathogen membranes.
– Antibodies make pathogens ineffective.
– Interferons prevent viruses from infecting healthy
cells.
Immunity prevents or limits a
person from getting sick from a
pathogen.
In all immunity, pathogens are destroyed
before you get sick.
Passive immunity occurs without an
immune response.
– mother’s milk
– genetics
Active immunity occurs after a specific
immune response
Immune Response
The immune system has
many responses to pathogens
and foreign cells.
Many body systems work to
produce nonspecific responses.
Nonspecific responses are the same for
every pathogen.
In inflammation, blood vessels become
leaky.
– white blood cells move toward infection and
damaged tissue
– characterized by swelling, redness, and pain
In fever, body temperature increases.
– Low fevers stimulate white blood cells to
mature.
– High fevers can cause seizure, brain damage,
and even death.
Cells of the immune system
produce specific responses.
Specific immune responses begin with the
detection of antigens.
– Antigens are surface proteins on pathogens.
– Each pathogen has a different antigen.
There are two specific immune responses.
– Cellular immunity uses T cells to destroy
infected body cells.
– Humoral immunity uses B cells to produce
antibodies.
Both responses produce memory cells.
– specialized T and B cells
– provide acquired (active) immunity
The immune system rejects foreign
tissues.
Tissue rejection occurs in organ or tissue
transplants.
Tissue rejection is the result of an immune
response.
– immune system detects protein markers on
the donor tissue
– makes antibodies against the donor’s tissue
Immunity and Technology
Living in a clean environment
and building immunity help
keep a person healthy.
Many methods are used to control
pathogens.
Antibiotics and antiseptics cause
pathogens to burst.
Antiseptics kill pathogens outside of the
body.
– do not target specific pathogens
– examples include vinegar and soap
Antibiotics kill pathogens inside the body.
– target one specific bacterium or fungus
– not effective against viruses
Antibiotic resistance can cause medicines
to become ineffective.
– Some bacteria in a population have genes
that make them immune to antibiotics.
– These bacteria spread the gene, making the
antibiotics useless.
Vaccines artificially produce
acquired immunity.
Vaccines also control pathogens and
disease.
– given to prevent illness
– contain the antigen of a weakened pathogen
l Vaccination provides immunity.
– stimulates a specific immune response
– causes memory cells to be produced
– allows immune system to respond quickly to
infection
Overreaction of the Immune
System
An overactive immune system
can make the body very
unhealthy.
Allergies occur when the immune
system responds to harmless
antigens.
An allergy is an response to a harmless
antigen.
Allergies are caused by allergens.
– Allergens are antigens that cause an allergic
reaction.
– Allergens cause inflammation responses.
There are many different allergens.
– food, e.g. peanuts, milk, wheat, etc.
– airborne, e.g. pollen, dust mite feces, mold,
etc.
– chemical, e.g. nickel, medicine, bee stings,
etc.
Allergens can cause anaphylaxis.
– Anaphylaxis is an extreme inflammation
response.
– Blood vessels and airways become too
porous.
– If not treated immediately, anaphylaxis can
cause death.
In autoimmune diseases, white
blood cells attack the body’s
healthy cells.
Autoimmune diseases are failures of the
immune system.
– White blood cells cannot recognize healthy
cells.
– White blood cells attack healthy body cells.
– Tissues fail because of attack.
– There are over 60 autoimmune diseases.