is now rarely performed due to the
treatment, often using
to measure higher mental functions
rather than more primitive abilities. The
Binet test was devised in 1905.
An alternative term for the eating disor-
A prefix describing a relationship to
life, as in biology, the science of life.
The proportion of a drug that reaches
the target organs and tissues, usually
expressed as a percentage of the dose
administered. Intravenous administration
of a drug results in 100 per cent bio-
availability because the drug is injected
directly into the bloodstream. Drugs
taken orally have a much lower bio-
availability. Preparations that have equal
bioavailabilities are described as bio-
equivalent. (See also
A science that studies the chemistry
of living organisms, including human
beings. The human body is made up of
millions of cells that require nutrients
and energy, and which grow, multiply,
and die. The chemical processes that are
involved in providing these cells with
energy, eliminating their wastes, repair-
ing damage, promoting cell growth,
and causing both normal and abnormal
cell division are all studied by bio-
chemists, the specialists in the field.
Life is maintained by a huge number
of chemical reactions that are carried
out inside cells. These reactions link
together in a complex way and together
make up the
of the body. The
reactions that produce energy and break
down food and body structures are
termed catabolism; those that build up
body structures and store food are
termed anabolism. Overall regulation of
these chemical processes is a principal
which are secreted
into the bloodstream by the
regulation of individual reactions
is carried out by
that promote biochemical reactions).
Certain vital chemical processes take
place in every single cell in the body.
Other, more specific, chemical processes
are confined to specialized cells that
make up the tissues of particular organs.
For example, liver cells store and chem-
ically modify the digestion products of
food; kidney cells help to control the
amounts of various substances (such as
certain minerals) in the blood, as well
as regulating the total amount of fluid
in the body.
A constant interchange of substances
occurs between the cell fluids and the
blood and urine. Biochemists can learn
a great deal about the chemical changes
occurring inside the body’s cells by reg-
ularly taking, and comparing, precise
measurements of the various minerals,
gases, enzymes, hormones, and proteins
in the different fluids of the body.
Such biochemical tests may be used
to make, or to confirm, a diagnosis, as
well as to screen for a particular disease
and to monitor its progress. The most
commonly used biochemical tests are
such tests include
liver function tests
kidney function tests.
Biochemical tests can also be performed
on urine (see
as well as on all
other body fluids.
A technique in which a person uses
information about a normally uncon-
scious body function, such as blood
pressure, to gain conscious control over
that function. This training may help to
treat stress-related conditions, including
HOW IT IS DONE
The doctor connects the patient to a
recording instrument that can measure
one of the unconscious body activities,
such as blood pressure, heart rate, mus-
cle tension, the quantity of sweat on the
skin, brain waves, or stomach acidity.
The patient receives information (feed-
back) on the changing levels of these
activities from changes in the instru-
ment’s signals, for example a flashing
light or sound changing tone.
After some experience with the tech-
nique, the person starts to become aware
of how he or she is feeling whenever
there is a change of signal. By using
the person learns to
change the signals by conscious control
of the function. Once acquired, control
can be exercised without the instrument.
A popular term for the inherent timing
physiological processes and cycles in
living organisms. (See also
The scientific study of all living organ-
isms, including animals, plants, and
isms). Biology involves the study of the
structure and functions of living organ-
organisms, and the ways in which they
interact with their environment. (See
A discipline that applies engineering
methods and principles to the body to
explain how it functions and to treat
disorders. Applications include the design
of artificial joints and heart valves, pace-
makers, and kidney dialysis machines.
A diagnostic test involving the removal
of small amounts of tissue or cells from
the body for microscopic examination.
A biopsy is an accurate method of diag-
nosing many illnesses, including cancer.
Microscopic examination of tissue (see
or of cells (see
gives a correct diagnosis.
HOW IT IS DONE
There are several types of biopsy. In
excisional biopsy, the whole abnormal
area is removed for study. Incisional
biopsy involves cutting away a small
sample of skin or muscle for analysis. In
a needle biopsy, a needle is inserted
through the skin and into the organ or
tumour to be investigated. Aspiration
biopsy uses a needle and syringe to
remove cells from a lump (see box).
Guided biopsy uses
to locate the area of tissue
to be biopsied and follow the progress
of the needle. In endoscopic biopsy, an
(viewing tube) is passed into
the organ to be investigated and an
attachment is used to take a sample
from the lining of accessible hollow
structures such as the lungs, stomach,
and bladder. In an open biopsy, a sur-
geon opens a body cavity to reveal a
diseased organ or tumour and removes
a sample. Prompt analysis, in some cases
(in which the tissue is
frozen and thinly sliced), can enable the
surgeon to decide whether to remove
the entire diseased area immediately.