Lesson Overview
Immune System Disorders
Lesson Overview
35.4 Immune
System Disorders
Lesson Overview
Immune System Disorders
THINK ABOUT IT do not write
A healthy immune system accurately distinguishes “self” from “other”
and responds appropriately to dangerous invaders in the body.
Sometimes, however, the immune system attacks the wrong targets.
Other times, the immune system itself is disabled by disease.
What happens in these cases?
Lesson Overview
Immune System Disorders
Autoimmune Diseases
Sometimes a disease occurs in which the immune system fails to
properly recognize “self,” and it attacks cells in the body like they were
pathogens.
When the immune system attacks the body’s own cells, it produces an
autoimmune disease.
Examples of autoimmune diseases are Type I diabetes, rheumatoid
arthritis, and lupus.
Lesson Overview
Immune System Disorders
When the Immune System “Misfires”
How can misguided immune responses cause problems?
A strong immune response to harmless antigens can produce allergies,
asthma, and autoimmune disease.
When the immune system attacks the body’s own cells, it produces an
autoimmune disease.
Lesson Overview
Immune System Disorders
HIV and AIDS do not write
During the late 1970s, physicians reported serious infections by
microorganisms that didn't normally cause disease.
Healthy people suffer from pneumonia, rare forms of skin cancer, &
fungal infections of the mouth and throat.
Doctors concluded that these patients must have weakened immune
systems.
Diseases that attack a person with a weakened immune system =
opportunistic diseases.
Lesson Overview
Immune System Disorders
HIV and AIDS
Doctors ultimately recognized that these illnesses were symptoms of a
new disorder they called acquired immunodeficiency syndrome (AIDS).
In 1983, researchers identified the cause of AIDS—a virus they called
human immunodeficiency virus (HIV).
Lesson Overview
Immune System Disorders
HIV
HIV is deadly for two reasons.
First, HIV can hide from the defenses of the immune system.
Second, HIV attacks key cells within the immune system, leaving the
body with inadequate protection against other pathogens.
Lesson Overview
Immune System Disorders
Targets: Helper T Cells
HIV travels through the blood, where it binds to helper T cells—the
command centers of the specific immune response.
Once inside the cell, the virus directs the cell to produce many new
viruses.
These new viruses are quickly released back into the blood, where they
infect new cells.
Lesson Overview
Immune System Disorders
Target: T Cells
HIV destroys T cells, crippling the ability of the immune system to fight
HIV and other pathogens.
Monitoring progression of HIV by counting helper T cells.
The fewer helper T cells, the more susceptible to other diseases.
When an HIV-infected person’s T cell count reaches about 1/6 the
normal level, he/ she is diagnosed with AIDS.
Lesson Overview
Immune System Disorders
HIV Transmission
HIV is not easily transmitted.
*NOT ~coughing/sneezing/sharing clothes/casual contact.
*IS ~contact with infected blood/semen/vaginal secretions/breast milk.
The four main ways that HIV is transmitted:
sexual intercourse with an infected person
sharing needles with an infected person
contact with infected blood or blood products
From infected mother to child: pregnancy/birth/ breast-feeding.
Lesson Overview
Immune System Disorders
Preventing HIV Infection
You choose behaviors that reduce your risk of becoming infected with
HIV.
Committed relationship
People who share needles for drugs are at an increased risk.
People who have sex with drug abusers increase risk.
Before 1985, HIV was transmitted to some patients through transfusions
of infected blood or blood products.
eliminated by screening blood for HIV antibodies & by discouraging
potentially infected individuals from donating blood.
Lesson Overview
Immune System Disorders
Preventing HIV Infection
This graph shows the increase in cases 13-24-year-olds living with
AIDS in the United States.
Lesson Overview
Immune System Disorders
Can AIDS Be Cured?
At present, there is no cure for AIDS.
New drugs, however, make it possible to survive HIV infection for years.
HIV mutates & evolves rapidly.
The virus has evolved into many strains that are resistant to most drugs
used against them.
No one has developed a vaccine that offers protection for any length of
time.
Lesson Overview
Immune System Disorders
Can AIDS Be Cured?
To control use a combination of expensive drugs.
Drugs interfere with the enzymes HIV uses to insert its RNA into a host
cell