Lecture Notes:

DISEASE AND THE IMMUNE SYSTEM

• AIDS is caused by a tiny germ called a virus.
• A virus is a tiny particle that has the ability to infect cells.
• Viruses are thousands of times smaller than cells and are millions of times smaller than a human.
• When cells become infected with a virus they start to die.
• If too many cells die, the person becomes sick.
• The virus that causes AIDS is HIV.
• Viruses attack the immune system.
• The immune system is the body's defense system.
• This defense system provides us with protection from disease.
• The parts of the immune system.
• skin
  a.) protective layer
  b.) We have skin to hold heat inside the body, regulate temperature, and keeps out germs.
  c.) Our skin is a mildly acidic surface which is a poor habitat for bacteria.
• mucus membrane
  a.) eyes, nose, mouth, anus, vagina, opening of penis
  b.) Secretes an enzyme that degrades foreign substances.
  c.) Good habitat for viruses.
  d.) The weak part of our body in terms of sites for infection.
• white blood cells
  a.) engulf (surround) bacteria and destroy it
  b.) produce antibodies.  An antibody is a protein that is produced by B-cells as part of the immune response.  Antibodies attach themselves to viruses.
• B-cells
  a.) If a germ is really strong, the B-cell is called in.
  b.) If germ is too strong for the B-cells, the T-cell is called in.
  c.) B-cell attaches itself to viruses
• T-cells
  a.) Three types of T-cells
      1.) Helper: increase in development of B-cells and other T-cells
      2.) Suppresser: once everything is contained, it turns off the immune response
      3.) Killer: attacks germs that the normal B-cells and T-cells can't handle
  b.) AIDS diagnosis is when T-cell count is less than 200.

• HIV seeks out the T-cells and attacks them.
• HIV destroys T-cells.
• The result: a reduction in antibodies and white blood cells die.
• The disease process from the point of infection
• People with AIDS: 2%-5%
• People with HIV-related complex: 5%-8%
• HIV positive : 90%-92% (most people with HIV don't even know they have it)

• Abstaining from sexual intercourse is the most effective HIV prevention strategy.
• For sexually active individuals: the following are highly effective:
  a.) Engaging in sexual activities that do not involve vaginal, anal, or oral intercourse.
  b.) Having intercourse with only one uninfected partner.
  c.) Using latex condoms correctly from start to finish with each act of intercourse.