Caused by a variety of organisms ?
Virii Explain how skin and mucous membranes act as barriers against microbes o
the skin, with its tough layer of keratin, is an
impregnable barrier as long as it is intact. When it is not, large numbers of
micro organisms gain ready entry to the body. o
Epithelium that forms mucous membranes ?
is more fragile than the skin ?
is constantly flushed with fluids, such as mucus,
saliva and tears, that contain antimicrobial substances. ?
The epithelium lining of the respiratory tract is
carpeted with cilia, which sweep away inhaled organisms, dirt and debris
trapped in the protective layer of mucous. Explain how Phagocytic lymphocytes ingest disease causing
a foreign substance, usually a protein or
that when bound to a complementary antibody displayed
on the surface of a B lymphocyte or to a complementary T-cell receptor,
stimulates an immune response. o
a globular protein ?
synthesized by a B lymphocyte ?
to a foreign substance (antigen) with which it combines
specifically. Describe Antibody Production o
B lymphocytes in bone marrow produce during
antibody when recognising one type of antigen (surface recognition sites,
humoral immunity and memory cells, ) o
Antibody molecules contain an antigen binding site Describe AIDS o
The disease known as AIDS is a complicated illness that
may involve several phases. It is caused by a virus called HIV that can be
system responsible for warding off disease and leaves the victim susceptible to
various infections. The virus enters the bloodstream and destroys certain white
blood cells, called T lymphocytes, that play a key role in the functioning of
the immune system. o
The virus can also infect other types of cells in the
body, including the immune-system cells known as macrophages. Unlike T
lymphocytes, however, macrophages are not killed by the virus. In fact,
research has suggested that macrophages may carry the AIDS virus to healthy
AIDS is transmitted by direct contamination of the bloodstream with body fluids
that contain the AIDS virus, particularly blood and semen from an HIV-infected
person. The virus is usually transmitted through various forms of sexual
intercourse, the transfusion of virus-contaminated blood, or the sharing of
HIV-contaminated intravenous needles.