OVUM
OXYGEN THERAPY
after
ovulation,
releases progesterone
during the
2
nd half of the cycle.
After its release, the ovum travels along
the
fallopian tube
and, if
fertilization
does
not occur, is shed during
menstruation.
Regular menstruation usually means that
ovulation is occurring, except around
puberty
and approaching the
menopause
.
ovum The egg cell (female cell of repro-
duction). An ovum contains a nucleus
suspended in cytoplasm (a gel-like sub-
stance) and is surrounded by a protective
layer, the
zona pellucida
.
OVUM
About 1
million immature ova are pre-
sent in each ovary at birth, but only
about
200
per ovary mature to be
released at
ovulation
. A
fertilized
ovum
develops into an
embryo.
oxazepam A
benzodiazepine drug
used
as a short-term treatment for
anxiety
.
Oxazepam may cause dependence if it
is taken regularly for more than
2
weeks
(see
drug dependence
).
oximeter An instrument used for mea-
suring the oxygen content of the blood.
oxprenolol A
beta-blocker drug
that is
used in the treatment of
hypertension
,
angina,
and cardiac
arrhythmias.
Ox-
prenolol may also be used to relieve
symptoms of
anxiety
and control those
of
hyperthyroidism
.
oxybutynin A drug that is used to treat
frequent urination (see
urination, fre-
quent)
by
increasing
the
bladder's
capacity. Common side effects include
dry mouth and blurred vision.
oxygen A colourless, odourless gas that
makes up 21 per cent of the Earth's atmo-
sphere. Oxygen is essential for almost all
forms of life, including humans, because
it is necessary for the metabolic “burn-
ing” of foods to produce energy - a
process that takes place in body cells
and is known as
aerobic
metabolism.
Oxygen is absorbed through the lungs
and into the blood, where it binds to
the
haemoglobin
in red blood cells. As
oxygen-rich blood circulates around the
body, the oxygen is released from the
red blood cells into the body tissues.
Additional supplies of oxygen are used
to treat conditions such as severe
bron-
chitis
or hj/poxia. High-pressure oxygen
(see
h}sperbaric oxjsgen treatment)
is
sometimes used to treat
decompression
sickness
or
carbon monoxide
poisoning.
(See also
ozone.)
oxygen concentrator
An appliance
used in
oxygen therapy
that separates
oxygen from the air and mixes it back in
at a greater concentration. This oxygen-
enriched air is delivered through a tube
for prolonged inhalation. The appliance
is used by people who have persistent
hj/poxia due to severe chronic obstruc-
tive pulmonary disease (see
pulmonary
disease
,
chronic obstructive).
(See also
h}sperbaric oxygen treatment.)
oxygen therapy
The process of supply-
ing a person with oxygen-enriched air
to relieve severe
hypoxia
(inadequate
OXYGEN THERAPY
Humidifier
Oxygen tube
keeps the
oxygen
Oxygen
moist .
concentrator
Nasal
cannulas
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