a bleeding disorder, or a tumour of the
nose or paranasal sinuses.
Fracture of the nasal
bones or dislocation of the cartilage
that forms the bridge of the
is usually accompanied by
severe swelling of overlying soft tissue.
A fractured nose is painful and remains
tender for about 3 weeks after injury.
Resetting is usually carried out either
before the swelling has started, or when
it has subsided, usually about
after the injury. Occasionally, a dis-
placed bridge can be manipulated into
position under a local anaesthetic, but,
usually, a general anaesthetic is needed.
A plaster splint is sometimes required
A term meaning associated
with hospitals. A nosocomial infection
is one acquired by a patient in hospital.
that must be reported to the local
health authorities. Notification of certain
potentially harmful infectious diseases
enables health officers to monitor and
control the spread of infection.
Examples of notifiable infectious dis-
food poisoning, hepatitis,
measles, malaria, tetanus, tuberculosis,
Some categories of diseases other
than infections must also be reported.
These include certain
registered nationally, and cancer data is
now pooled in an international registry.
Certain types of
are also reportable; examples include
lead poisoning, mercury poisoning, cad-
. (See also
An abbreviation for nonspecific
urethritis, the former term for
performed in early pregnancy
in order to identify fetuses at high risk
The scan investigates
the nuchal fold, an area of skin at the
back of the neck. Excessive thickness of
the skin is an indicator of possible chro-
The energy released as
a result of changes in the nuclei of
atoms. It is also known as atomic energy
and is principally released in the form
of heat, light, and ionizing
such as gamma rays.
Nuclear energy is released in certain
natural processes, including the sponta-
neous decay of radioactive substances
such as uranium ores, and the nuclear
reactions that power the sun. It is also
what powers nuclear reactors.
nuclear magnetic resonance
Techniques that use
radioactive substances to detect or
Radioactive materials, which may be
injected or swallowed, are taken up by
body tissues or organs in different con-
centrations, and an instrument called a
gamma camera is used to detect and
map the distribution of radiation within
the body (see
techniques for treatment, diseased tis-
sues are destroyed by exposure to an
external radioactive source or by inser-
tion of a radioactive substance (see
Substances found in all
living matter that have a fundamental
role in the propagation of life. Nucleic
instructions (or “blueprint”) for an org-
There are 2 types of nucleic acid: deoxy-
ribonucleic acid (DNA) and ribonucleic
acid (RNA). In all plant and animal cells,
including human cells, DNA permanently
holds the coded instructions, which are
translated and implemented by RNA.
DNA is the main constituent of
, which are carried in the nucleus
(central unit) of the cell.
DNA and RNA are similar in structure,
both comprising long, chain-like mole-
cules. However, DNA usually consists of
2 intertwined chains, whereas RNA is
The basic structure of DNA has been
likened to a rope ladder, the chains
sides, with interlinking
structures in between forming the rungs.