Transcript Immune System

Immune System
Standards:
SAP 1 – Students will analyze anatomical
structures in relationship to their
physiological functions.
SAP 4 – Students will analyze the physical,
chemical, and biological properties of
process systems as these relate to
transportation, absorption, and
excretion, including the
cardiovascular, respiratory, digestive,
excretory, and immune systems.
Pathogens are disease causing
organisms
examples: bacteria, viruses, fungi
and protists
The body has 3 main lines of defense to
prevent invading microbes from getting
the upper hand
First line of defense
Made up of the skin and mucous
membranes
• skin covers the outside of
the body
• mucous membranes line the
body’s internal surfaces
(digestive tract, nasal passages,
respiratory passages, and
reproductive tract)
Together, the skin and mucous
membranes function to prevent
microbes from entering the
body
• when pathogens penetrate the 1st
line of defense (through cuts or
wounds), the 2nd line of defense
comes into play
Second line of defense
Made up of:
1. Three types of cells that kill
invading microbes
a. Macrophages are WBCs
that travel through the
body to kill invading
bacteria by ingesting them
b. Neutrophils are WBCs that
release chemicals that kill
invading bacteria and
themselves in the process
c. Natural killer cells are
defense cells that kill any
body cell that has become
infected with a virus
• more importantly, natural
killer cells are our best
defense against cancer
• they detect and kill cancer
cells before they can form
tumors
2. Complement – is a group of
proteins that circulate in your
bloodstream
• they function to kill invading
bacteria and fungi
3. The inflammatory response is to
series of events that functions
to suppress infection and
speed healing
• it occurs anytime you
have been injured
A series of events occur during an
inflammatory response
1. Damage cells release alarm
chemical that
2. Attract neutrophils and
macrophages to the damaged
area which
3. Cause local blood vessels to
dilate increasing blood supply
to the damaged area
• This is what causes the four
classical symptoms of
inflammation (heat, redness,
pain, and swelling)
The cardinal signs of
inflammation are rubor (redness),
calor (heat), tumor (swelling),
dolor (pain), and loss of function.
4. Temperature response – activated
macrophages (those
consuming invading bacteria)
send signals to the brain to
increase your body
temperature above normal
(98.6F / 37C)
Low grade temperatures (less
than 103F/ 39C) speed the
healing process because they
inhibit the growth of bacteria
However, high grade
temperatures (greater than
105 F/ 41C) are often fatal
because they destroy
important enzymes in the body
Third line of defense
Made up of your immune system
It functions to combat major
invasions, and comes into play only
when your first 2 lines of defense
have failed to kill the invading
pathogens
1. Key players in the immune
system
a. Macrophages – WBCs that
initiate the immune
response
• they release an alarm
signal that functions
to activate Helper T
cells
b. Helper T cells – WBCs that
function to activate
Killer T cells and B cells
c. Killer T cells – WBCs that
recognize and kill body
cells infected with a virus
d. B cells – WBCs that produce
antibodies that mark
pathogens for destruction
by macrophages and
natural killer cells
• some of these activated B
cells will become memory
cells that remain in your
body for a long time –
sometimes for life
These memory B cells are programmed
to recognize the same pathogen that
they encountered earlier in you life
If they ever encounter that same
pathogen again, they rapidly produce
large amounts of antibodies that destroy
the pathogen before they have a chance
to cause the disease a second time
2. Vaccination – prevent disease by
tricking your immune system
into thinking your body has
been invaded by a particular
pathogen
The vaccine you receive usually
contains a dead or disabled
pathogen which cannot cause
disease, but does result in the
formation of memory B cells that
patrol the body preventing future
infections by the same pathogen
Vaccinations exists for many
diseases: polio, tetanus,
diphtheria, measles, and smallpox
Polio
Tetnus
Diphtheria
Diphtheria
Measles
Measles
Smallpox
Smallpox
Smallpox
Smallpox vs. Chickenpox
• smallpox vaccinations are no
longer required because this
disease has been eradicated from
the earth
Malfunctions and Failures of the
Immune System
1. Autoimmune diseases –
diseases in which the
body attacks its own cells
• we do not know what
triggers the development
of these diseases
There are several different types of
autoimmune diseases:
a. Multiple sclerosis occurs when
the immune system attacks
and slowly destroys the
myelin sheath that
surrounds and protects
your nerves
As the myelin is destroyed, your
nerves lose their ability to
conduct impulses
This results in progressively
worsening paralysis and
eventually death
• there is no cure
b. Systemic lupus erythematosus –
occurs when the immune
system attacks and destroys
your connective tissue, joints,
and kidneys
Eventually causes death
• there is no cure
c. Type 1 diabetes – occurs when
the immune system destroys
insulin-producing cells in the
pancreas
• there is no cure, but can be
controlled by taking daily
insulin injections
d. Rheumatoid arthritis – occurs
when the immune system
attacks and destroys cartilage
in your joints
As the cartilage is destroyed,
bone begins rubbing against bone
causing tremendous pain
• there is no cure
2. Allergies – occur when the
immune system mounts a
major attack against a
normally harmless substance
For example, if you are allergic
to pollen, your immune system
treats the pollen as if it were a
pathogen, causing nasal
congestion and a runny nose
3. SCID (severe combined
immunodeficiency) – a rare
disease in which a person is
born with missing or inactive
B cells and T cells
This person has no immune
system. Thus, they could be
killed by a cold virus
The most famous patient with SCID
was David, the “bubble boy”, who
lived in a sterile plastic bubble for
almost all of his life; he died in 1984
at the age of 12
4. AIDS (acquired immune
deficiency syndrome) –
disease caused by HIV
(human immunodeficiency
virus)
Although AIDS was first
recognized as a disease in 1981,
it has been around since 1959
HIV is transmitted by:
1. Sexual intercourse with an
infected person
2. Sharing hypodermic needles
with an infected person (IV
drug use)
3. Receiving blood transfusions
or blood products (factor
VIII used by hemophiliacs)
from an infected
individual
HIV is not transmitted through
air, on toilet seats, by shaking
hands or sharing food or drink
There is no cure. HIV transmission
can be prevented by not sharing
hypodermic needles and
abstinence.
Condoms can help prevent HIV
transmission, but there is no
guarantee
In 1989, it was discovered from
tissue samples that a British sailor
died of AIDS in 1959
HIV causes death by attacking
helper T cells. As a result killer T
cells and B cells cannot be
activated. Thus, the body is
susceptible to infections and cancer
HIV infected individuals are
considered to have AIDS when their
helper T cell count falls below
200/mL
(normal is 800 – 1000/mL)
Diseases that commonly cause
death in AIDS patients are:
Pneumocystis
pneumonia
Kaposi’s sarcoma
(cancer of skin and
mucous membranes)