BIOENGINEERING
BIOPSY
B
function tests.
Biochemical tests can
also be performed on urine (see
urinaly-
sis)
and other body fluids.
bioengineering
See
biomechanical eng-
ineering.
biofeedback training
A technique in
which a person uses information about a
normally unconscious body function to
gain conscious control over that func-
tion. Biofeedback training may help in the
treatment of stress-related conditions,
including certain types of
hypertension
,
anxiety,
and
migraine.
BIOFEEDBACK TRAINING
Monitor displays
The patient is connected to a record-
ing instrument that measures one of
the unconscious body activities, such
as blood pressure, heart-rate, or the
quantity of sweat on the skin. The
patient receives information (feedback)
on the changing levels of these activi-
ties from changes in the instrument's
signals. Using
relaxation techniques,
the
patient learns to change the signals by
conscious control of the body function.
Once acquired, this control can be exer-
cised without the instrument.
biological clock
A popular term for the
inherent timing mechanism that suppos-
edly controls physiological processes
and cycles in living organisms. (See
also
biorhythms.)
biomechanical engineering
A disci-
pline that applies engineering methods
and principles to the body to explain how
it functions and to treat disorders. Prac-
tical applications include the design of
artificial joints and heart valves, plaster
casts, and kidney dialysis machines.
biopsy
A diagnostic test in which a
small amount of tissue or cells are
removed from the body for microscopic
examination. It is an accurate method
of diagnosing many illnesses, including
cancer. Microscopic examination of tis-
sue (
histology
) or of cells (
cytology
)
usually gives a correct diagnosis.
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 solid lump. Guided
biopsy uses
ultrasound scanning
or
CT
scanning
to locate the area of tissue to
be biopsied and to follow the progress
of the needle. In endoscopic biopsy, an
endoscope
is passed into the organ to
be investigated and an attachment is
used to take a sample from the lining of
accessible hollow organs and struc-
tures,
such as the lungs, stomach,
colon, and bladder. In an open biopsy,
a surgeon opens a body cavity to reveal a
diseased organ or tumour and removes
a sample of tissue. Prompt analysis, in
some cases
by
frozen section
,
can
enable the surgeon to decide whether
to remove the entire diseased area
immediately.
Biopsy samples
are analysed by
s
taining
, in which
dyes are used to
to show up struc-
tures or identify
constituents such
as
antibodies
or
enzymes
. A tissue
sample may be
tested with speci-
fic antibodies in
the investigation
of infection and
inflammation. In
some cases, a tis-
sue
culture
may
be required.
EXCISIONAL SKIN
BIOPSY
74
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