The majority of miscarriages occur in
weeks of pregnancy, and may
be mistaken for a late menstrual period.
Miscarriages may occur because of
mental defects in the fetus, or because
of severe illness, exposure to toxins, or
in the mother.
Miscarriages later in pregnancy may be
, a defect in the uterus, or
The symptoms are heavy bleeding with
cramping. Slight blood loss with severe
pain can be a symptom of either a threat-
ened miscarriage or
Miscarriages are classified medically
as different types of abortion. In a
threatened abortion, the fetus remains
alive in the uterus. In an inevitable
abortion, the fetus dies and is expelled
from the uterus. In a missed abortion,
the fetus dies but remains in the uterus.
may be performed to assess
the pregnancy. If all of the contents of
the uterus are expelled, no further treat-
ment may be necessary. Otherwise, a
may be performed. Missed abor-
tion requires a D and C or
depending on the duration of the
given anti-D (Rho) immunoglobulin to
prevent complications related to
in future pregnancies.
that inhibits gastric secretion. Miso-
prostol is used to prevent and treat
associated with use of
nonsteroidal anti-inflammatory drugs.
mites and disease
Mites are small ani-
mals, usually less than
legs. Many species have piercing and
Species causing disorders include the
mite, which burrows in human
skin causing intense itching; the house-
dust mite, which can cause
when inhaled in dust; and chiggers
(American harvest mites), which are
found in thick grass and cause an itchy
rash when they bite. Mites in grain or
fruit may cause skin irritation, some-
times known as grocers' or bakers' itch.
Certain mites transmit diseases, partic-
, in which cell
takes place. The mitochondrial wall
membranes, and the inner
one is highly folded to provide a surface
for the respiration reactions. Cells that
use a lot of energy, such as muscle
cells, contain many mitochondria.
. In human mitochondria,
the DNA is a double-helical circle that
codes for 13 proteins. Mitochondria
have a distinctive genetic code, and
their genomes are not changed by
the DNA useful in genetic studies.
The significance of mitochondria hav-
ing their own DNA is that diseases can
be inherited via abnormalities of mito-
chondrial DNA, and inheritance of the
DNA is maternal, directly from the egg.
A type of cell division in which
within the nucleus of
a cell are exactly duplicated into each of
Before cell division, the chromosomes
duplicate themselves and coil up with
the 2 copies joined together. The dou-
bled chromosomes line up in the centre
of the cell and are pulled apart to oppo-
site ends of the cell, which then divides.
Each daughter cell therefore has the
same chromosome content as the origi-
nal cell. (See also
Failure of the
to close properly,
allowing blood to leak back into the left
atrium (upper chamber) when pumped
out of the left ventricle (lower cham-
ber). The disorder, which is also known
as mitral regurgitation, may occur in
Symptoms include increasing breath-
lessness and fatigue, sometimes with
. Later, the ankles may swell.
Diagnosis may be made by hearing a
, and from
may also be per-
formed. Treatment may include
If symptoms are disabling,
may be considered.