Transcript Prentice Hall Biology - Valhalla High School

The Immune System
Go to
Section:
The Immune System
•The body’s primary defense mechanism
•May destroy invaders by engulfing them by special cells or
by chemically marking them for destruction and elimination
•Functions by being able to recognize proteins on the surface
of cells
•It can distinguish between self and non-self
– The non-self, or invading foreign proteins are referred
to as antigens
Go to
Section:
Nonspecific vs. Specific
•Two types of defense mechanisms
– Non-specific – physical and chemical barriers
• 1st line of defense - Keep pathogens out of your
body
– Done by skin, mucous, sweat and tears
» The secretions contain lysozyme, an
enzyme which breaks down the cell
walls of bacteria
Go to
Section:
Section Outline
Section 40-2
•
Go to
Section:
2nd line of defense – inflammatory response
– If pathogens do enter your body, phagocytic white
blood cells move into the area to destroy the bacteria
– The immune system also releases a chemical that
increases your body temperature
» The fever kills the bacteria because they can only
exist in a narrow temperature range.
» The fever also increases heart rate so wbc can
get to the infection site faster.
Figure 40–7 The Inflammatory Response
Section 40-2
Skin
Wound
Phagocytes move into the
area and engulf the bacteria
and cell debris
Bacteria enter
the wound
Capillary
Go to
Section:
Specific Defense
•A specific defense against a pathogen is called an immune
response
– Pathogens that trigger this response are called antigens
• These may be viruses, bacteria or other pathogens such
as fungi, parasites, etc.
•The immune response attacks the particular disease-causing
agent with a response especially for that pathogen
•There are two types of wbc’s that recognize specific antigens
– B cells – humoral immunity – pathogens and antigens in
body fluids
– T cells – cell-mediated immunity – pathogens and antigens
inside living cells
Go to
Section:
Primary and Secondary Immune Responses
Antibody Concentration
Section 40-2
Interval
between
exposures
First
exposure
Second
exposure
Time
Go to
Section:
Acquired Immunity
•Two types of acquired immunity
– Active – appears after exposure to an antigen
• May be natural (the body fights an infection)
• May be artificial (through vaccination)
– Vaccine – injection of a weakened form of an antigen
to produce an immune response
– Passive – receiving antibodies to fight off an infection – only
lasts a short time because the body will eventually destroy
the foreign antibodies
• May be natural – antibodies are passed to a baby
through the placenta and through breast milk
• May be artificial – vaccines may contain antibodies to
protect and prevent disease
Go to
Section:
Section Outline
Section 40-3
Immune System Disorders
A. Allergies
B. Autoimmune Diseases
C. HIV and AIDS
Go to
Section:
Allergies
•An overreaction of the immune system
– Allergy causing antigens enter the body and attach
themselves to certain white blood cells
• These white blood cells initiate the inflammatory
response
– Produce chemicals called histamines
– Asthma – a chronic respiratory disease where the air
passages become narrower than normal, causing wheezing,
coughing and difficulty breathing
• May be treated with medications that relieve the
symptoms of asthma
Go to
Section:
Autoimmune Disorders
•The immune system has the ability to recognize self and non-self
– When the immune system makes a mistake and attacks its
own cells, it produces an autoimmune disease
• Examples
– Type I diabetes – insulin-producing cells of the
pancreas are destroyed
– Multiple sclerosis – antibodies destroy the functions
of the neurons in the brain and spinal cord
– Lupus – attacks normal connective tissue, leading to
inflammation and pain in the joints
– some of the autoimmune diseases may be treated with
immune suppressing drugs
• However, this therapy is not used often or must be
monitored carefully
Go to
Section:
HIV and AIDS
•AIDS is an autoimmune disease that results from
infection with HIV
– Normally healthy patients die from:
• microorganisms that don’t normally cause disease
• from extremely rare forms of cancers and pneumonia
• from pathogens that healthy people can normally fight
off
•HIV –is a virus that can evade the defenses of the
immune system and attacks key cells in the immune
system
Go to
Section:
Transmission and Prevention of HIV
•Transmitted through bodily fluids such as blood, semen,
vaginal secretions and breast milk
– Through any form of sexual intercourse
– Through shared needles that are contaminated with
infected blood
– Through contact with blood or blood products
– From infected mother to child, through pregnancy, birth
and/or breast feeding
Go to
Section: