phyto- A prefix meaning of plant origin.
phytomenadione A form of
cur naturally in plants.
pia mater The innermost of the 3 mem-
branes of the
pica A craving to eat non-food substan-
ces such as earth or coal. Pica is common
in early childhood and may occur during
pregnancy. It may also occur in nutri-
tional or iron-deficiency disorders, and
in severe psychiatric disorders.
Pickwickian syndrome An unusual dis-
order characterized by extreme
shallow breathing, and
cause is unclear. Symptoms usually im-
prove with weight loss.
pelvic inflammatory disease.
pigeon toes A minor abnormality in
which the leg or foot is rotated, forcing
the foot and toes to point inwards. The
condition is common in toddlers.
pigmentation Coloration of the skin,
of the eyes by
more melanin present, the darker the
coloration. Blood pigments can also
colour skin (such as in a bruise).
There are many abnormalities of pig-
mentation. Patches of pale skin occur in
is caused by
generalized melanin deficiency.
results in a reduced melanin
level, making sufferers pale-skinned and
fair-haired. Areas of dark skin may be
caused by disorders such as
psoriasis, pityriasis versicolor,
or by some perfumes and cosmetics
containing chemicals that cause
. Permanent areas of deep
pigmentation, such as freckles and moles
), are usually due to an
is characterized by dark patch-
es of velvet-like, thickened skin. Blood
pigments may lead to abnormal colour-
ing. Excess of the bile pigment bilirubin
turns the skin yellow, and
turns the skin bronze.
piles A common name for
pill, contraceptive See
pilocarpine A drug used to treat
. It may initially cause blurred vision,
headache, and eye irritation.
pilonidal sinus A pit in the skin, often
containing hairs, in the upper part of
the buttock cleft. The cause is probably
hair fragments growing inwards. Al-
though usually harmless, infection may
occur, causing recurrent, painful ab-
scesses. If a sinus is infected, a wide
area around it is surgically removed.
Recurrence of infection is common, and
plastic surgery is sometimes required.
used to treat
Gilles de la Tourette's syn-
. Pimozide may cause sedation, dry
mouth, constipation, and blurred vision.
pimple A small
Possible side effects are typical of other
beta-blocker drugs, except that pindolol
is less likely to cause
pineal gland A tiny, cone-shaped struc-
ture deep within the
, whose sole
function appears to be the secretion of
in response to changes in light.
pinguecula A small, noncancerous, yel-
lowish spot on the
white of the eye. They are common in
elderly people, and may be removed for
pinna The fleshy part of the outer ear,
consisting of a flap of cartilage and skin.
It is also called the
pins-and-needles A tingling or prickly
feeling in an area of skin that is usually