Human health and physiology - Antibodies and AIDS

Human health and physiology - Antibodies and AIDS

1. Production of antibodies

   • 1. Antibodies are made by lymphocytes, one of the two main types of leukocyte.
   • 2. A lymphocyte can only make one type of antibody so a huge number of different lymphocyte types are needed. Each lymphocyte puts some of the antibody that it can make into its plasma membrane with the antigen-combining site projecting outwards.
   • 3. When a pathogen enters the body, its antigen binds to the antibodies in the plasma membrane of one type of lymphocyte.
   • 4. When the antigen binds to the antibodies on the surface of a lymphocyte, this lymphocyte becomes active and divides by mitosis to produce a clone of many identical cells.
   • 5. The clone of cells starts to produce large quantities of the same antibody - the antibody needed to defend the body against the pathogen.

2. AIDS - a syndrome caused by a vius

   • AIDS shows how vital the bodies defenses against disease are.
     • Destruction of the immune system lead inevitably to death.
   • AIDS is an example of a syndrome.
     • A syndrome is a group of symptoms that are found together. Individuals with AIDS have low numbers of one type of lymphocyte together with weight loss and a variety of diseases cause by viruses, bacteria, fungi and protozoa. These diseases weaken the body and eventually cause death.
   • Cause:
     • HIV causes AIDS
     • The virus infects a type of lymphocyte that plays a vital role in antibody production.
     • Over a period of years these lymphocytes are destroyed and antibodies cannot be produced.
     • Without a functioning immune system, the body is vulnerable to pathogens that would normally be controlled easily.
   • Transmission
     • HIV does not survive for long outside of the body and cannot easily pass through the skin.
     • Transmission involves the transfer of bodily fluids from on an infected person to an uninfected one.
     • Through small cuts or tears in the vagina, penis, mouth or intestine during vaginal, anal or oral sex.
     • In traces of blood on a hypodermic needle that is shared by intravenous drug abusers.
     • Across the placenta from mother to baby, or through cuts during childbirth or in milk during breast-feeding.
     • In transfused blood or with blood products such as Factor VIII used to treat hemophiliacs.
   • Social Implications
     • Family and friends suffer grief.
     • Families become poorer if the individual with AIDS was the wage earner and is refused life insurance.
     • Individuals infected with HIV may become stigmatized and not find partners, housing or employment.
     • Sexual activity in a population may be reduced because of the fear of AIDS.